mirror of
https://github.com/flokoe/bash-hackers-wiki.git
synced 2024-11-01 14:53:06 +01:00
Merge pull request #15 from hansonchar/linkfix-depth3
Fix hyperlinks of markdown pages at depth 3
This commit is contained in:
commit
93e24b5962
@ -12,17 +12,17 @@ The `cd` builtin command is used to change the current working directory
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|||||||
|
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||||||
- to the given directory (`cd DIRECTORY`)
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- to the given directory (`cd DIRECTORY`)
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||||||
- to the previous working directory (`cd -`) as saved in the
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- to the previous working directory (`cd -`) as saved in the
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||||||
[OLDPWD](/syntax/shellvars#OLDPWD) shell variable
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[OLDPWD](../../syntax/shellvars.md#OLDPWD) shell variable
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||||||
- to the user\'s home directory as specified in the
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- to the user\'s home directory as specified in the
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||||||
[HOME](/syntax/shellvars#HOME) environment variable (when used
|
[HOME](../../syntax/shellvars.md#HOME) environment variable (when used
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||||||
without a `DIRECTORY` argument)
|
without a `DIRECTORY` argument)
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||||||
|
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The `cd` builtin command searches the directories listed in
|
The `cd` builtin command searches the directories listed in
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[CDPATH](/syntax/shellvars#CDPATH) for a matching directory.
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[CDPATH](../../syntax/shellvars.md#CDPATH) for a matching directory.
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||||||
|
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||||||
The default behaviour is to follow symbolic links unless the `-P` option
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The default behaviour is to follow symbolic links unless the `-P` option
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is given or the shell is configured to do so (see the `-P` option of
|
is given or the shell is configured to do so (see the `-P` option of
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||||||
[the set builtin command](/commands/builtin/set)).
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[the set builtin command](../../commands/builtin/set.md)).
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|
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### Options
|
### Options
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||||||
|
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@ -36,7 +36,7 @@ is given or the shell is configured to do so (see the `-P` option of
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|
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- true if the directory was changed successfully
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- true if the directory was changed successfully
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- false if a change to the home directory was requested, but
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- false if a change to the home directory was requested, but
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[HOME](/syntax/shellvars#HOME) is unset
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[HOME](../../syntax/shellvars.md#HOME) is unset
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- false if anything else goes wrong
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- false if anything else goes wrong
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|
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## Examples
|
## Examples
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@ -53,7 +53,7 @@ is given or the shell is configured to do so (see the `-P` option of
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|||||||
|
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## See also
|
## See also
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||||||
|
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- variable [CDPATH](/syntax/shellvars#CDPATH)
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- variable [CDPATH](../../syntax/shellvars.md#CDPATH)
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- variable [HOME](/syntax/shellvars#HOME)
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- variable [HOME](../../syntax/shellvars.md#HOME)
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- variable [OLDPWD](/syntax/shellvars#OLDPWD)
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- variable [OLDPWD](../../syntax/shellvars.md#OLDPWD)
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- the `-P` option of [the set builtin command](/commands/builtin/set)
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- the `-P` option of [the set builtin command](../../commands/builtin/set.md)
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@ -176,9 +176,9 @@ for details. ksh93 namerefs are much more powerful than Bash\'s.
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|||||||
|
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## See also
|
## See also
|
||||||
|
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||||||
- [arrays](/syntax/arrays)
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- [arrays](../../syntax/arrays.md)
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- [readonly](/commands/builtin/readonly)
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- [readonly](../../commands/builtin/readonly.md)
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||||||
- [unset](/commands/builtin/unset)
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- [unset](../../commands/builtin/unset.md)
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||||||
- [declaration commands](http://austingroupbugs.net/view.php?id=351)
|
- [declaration commands](http://austingroupbugs.net/view.php?id=351)
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||||||
will change the behavior of certain builtins such as `export` in the
|
will change the behavior of certain builtins such as `export` in the
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||||||
next version of POSIX.
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next version of POSIX.
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||||||
|
@ -8,7 +8,7 @@
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|||||||
|
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||||||
`echo` outputs it\'s args to stdout, separated by spaces, followed by a
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`echo` outputs it\'s args to stdout, separated by spaces, followed by a
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||||||
newline. The return status is always `0`. If the
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newline. The return status is always `0`. If the
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||||||
[shopt](/commands/builtin/shopt) option `xpg_echo` is set, Bash
|
[shopt](../../commands/builtin/shopt.md) option `xpg_echo` is set, Bash
|
||||||
dynamically determines whether echo should expand escape characters
|
dynamically determines whether echo should expand escape characters
|
||||||
(listed below) by default based on the current platform. `echo` doesn\'t
|
(listed below) by default based on the current platform. `echo` doesn\'t
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||||||
interpret `--` as the end of options, and will simply print this string
|
interpret `--` as the end of options, and will simply print this string
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||||||
@ -69,7 +69,7 @@ if given.
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|||||||
```
|
```
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||||||
- **Never use options to `echo`! *Ever*!** Any time you feel tempted
|
- **Never use options to `echo`! *Ever*!** Any time you feel tempted
|
||||||
to use `echo -e`, `-n`, or any other special feature of echo, **use
|
to use `echo -e`, `-n`, or any other special feature of echo, **use
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||||||
[printf](/commands/builtin/printf) instead!** If portability is a
|
[printf](../../commands/builtin/printf.md) instead!** If portability is a
|
||||||
requirement, you should consider using `printf` *exclusively* and
|
requirement, you should consider using `printf` *exclusively* and
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||||||
just ignore that `echo` even exists. If you must use `echo -e` and
|
just ignore that `echo` even exists. If you must use `echo -e` and
|
||||||
refuse to use `printf`, it is usually acceptable to use \'\'echo
|
refuse to use `printf`, it is usually acceptable to use \'\'echo
|
||||||
@ -81,12 +81,12 @@ if given.
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|||||||
```
|
```
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||||||
- `ksh93` has a `print` command, which if coding specifically for
|
- `ksh93` has a `print` command, which if coding specifically for
|
||||||
`ksh93` should be preferred over `echo`.
|
`ksh93` should be preferred over `echo`.
|
||||||
[printf](/commands/builtin/printf) still includes most of the
|
[printf](../../commands/builtin/printf.md) still includes most of the
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||||||
functionality of both, and should usually be the most preferred
|
functionality of both, and should usually be the most preferred
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||||||
option.
|
option.
|
||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [printf](/commands/builtin/printf)
|
- [printf](../../commands/builtin/printf.md)
|
||||||
- <http://cfajohnson.com/shell/cus-faq.html#Q0b>
|
- <http://cfajohnson.com/shell/cus-faq.html#Q0b>
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||||||
- <http://www.in-ulm.de/~mascheck/various/echo+printf/>
|
- <http://www.in-ulm.de/~mascheck/various/echo+printf/>
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||||||
|
@ -18,7 +18,7 @@ a child process.
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|||||||
## Examples
|
## Examples
|
||||||
|
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||||||
In this example, the literal text within the
|
In this example, the literal text within the
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||||||
[here-document](/syntax/redirection#here_documents) is executed as Bash
|
[here-document](../../syntax/redirection.md#here_documents) is executed as Bash
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||||||
code exactly as though it were to appear within the script in place of
|
code exactly as though it were to appear within the script in place of
|
||||||
the `eval` command below it.
|
the `eval` command below it.
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||||||
|
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@ -135,10 +135,10 @@ first example above is the same error as the second in all non-Bash
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|||||||
shells, even those with compound assignment.
|
shells, even those with compound assignment.
|
||||||
|
|
||||||
In the case of `eval` it isn\'t recommended to use this behavior,
|
In the case of `eval` it isn\'t recommended to use this behavior,
|
||||||
because unlike e.g. [declare](commands/builtin/declare), the initial
|
because unlike e.g. [declare](../../commands/builtin/declare.md), the initial
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||||||
expansion is still subject to all expansions including
|
expansion is still subject to all expansions including
|
||||||
[word-splitting](syntax/expansion/wordsplit) and [pathname
|
[word-splitting](../../syntax/expansion/wordsplit.md) and [pathname
|
||||||
expansion](syntax/expansion/glob).
|
expansion](../../syntax/expansion/glob.md).
|
||||||
|
|
||||||
$ ( set -x; touch 'x+=(\[[123]\]=*)' 'x+=([3]=yo)'; eval x+=(*); echo "${x[@]}" )
|
$ ( set -x; touch 'x+=(\[[123]\]=*)' 'x+=([3]=yo)'; eval x+=(*); echo "${x[@]}" )
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||||||
+ touch 'x+=(\[[123]\]=*)' 'x+=([3]=yo)'
|
+ touch 'x+=(\[[123]\]=*)' 'x+=([3]=yo)'
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||||||
@ -149,14 +149,14 @@ expansion](syntax/expansion/glob).
|
|||||||
[[123]]=* yo
|
[[123]]=* yo
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||||||
|
|
||||||
Other commands known to be affected by compound assignment arguments
|
Other commands known to be affected by compound assignment arguments
|
||||||
include: [let](commands/builtin/let),
|
include: [let](../../commands/builtin/let.md),
|
||||||
[declare](commands/builtin/declare),
|
[declare](../../commands/builtin/declare.md),
|
||||||
[typeset](commands/builtin/typeset), [local](commands/builtin/local),
|
[typeset](../../commands/builtin/typeset.md), [local](../../commands/builtin/local.md),
|
||||||
[export](commands/builtin/export), and
|
[export](../../commands/builtin/export.md), and
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||||||
[readonly](commands/builtin/readonly). More oddities below show both
|
[readonly](../../commands/builtin/readonly.md). More oddities below show both
|
||||||
similarities and differences to commands like
|
similarities and differences to commands like
|
||||||
[declare](commands/builtin/declare). The rules for `eval` appear
|
[declare](../../commands/builtin/declare.md). The rules for `eval` appear
|
||||||
identical to those of [let](commands/builtin/let).
|
identical to those of [let](../../commands/builtin/let.md).
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||||||
|
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||||||
## See also
|
## See also
|
||||||
|
|
||||||
|
@ -28,7 +28,7 @@ shell without executing any program.
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|||||||
- on redirection errors it returns 1, otherwise 0
|
- on redirection errors it returns 1, otherwise 0
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||||||
- on exec failures:
|
- on exec failures:
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||||||
- a non-interactive shell terminates; if the [shell option
|
- a non-interactive shell terminates; if the [shell option
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||||||
execfail](/internals/shell_options#execfail) is set `exec`
|
execfail](../../internals/shell_options.md#execfail) is set `exec`
|
||||||
returns failure
|
returns failure
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||||||
- in an interactive shell, `exec` returns failure
|
- in an interactive shell, `exec` returns failure
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||||||
|
|
||||||
@ -82,4 +82,4 @@ exec >/var/adm/my.log 2>&1
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|||||||
|
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||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [redirection](/syntax/redirection)
|
- [redirection](../../syntax/redirection.md)
|
||||||
|
@ -12,7 +12,7 @@ If `N` is given, the return code to the parent process is set to `N`. If
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|||||||
not, the returned status the the status of the most recently executed
|
not, the returned status the the status of the most recently executed
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||||||
command (i.e. `$?`).
|
command (i.e. `$?`).
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||||||
|
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||||||
A [trap](/commands/builtin/trap) on `EXIT` is executed before the shell
|
A [trap](../../commands/builtin/trap.md) on `EXIT` is executed before the shell
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||||||
exits, except the executed `exit` command is part of an already running
|
exits, except the executed `exit` command is part of an already running
|
||||||
trap.
|
trap.
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||||||
|
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@ -42,5 +42,5 @@ executed the `exit` command, because the shell exits.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [The trap builtin command](/commands/builtin/trap)
|
- [The trap builtin command](../../commands/builtin/trap.md)
|
||||||
- [The exit status](/dict/terms/exit_status)
|
- [The exit status](../../dict/terms/exit_status.md)
|
||||||
|
@ -49,4 +49,4 @@ Set your default text editor (e.g. SublimeText):
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [declare](/commands/builtin/declare)
|
- [declare](../../commands/builtin/declare.md)
|
||||||
|
@ -7,27 +7,27 @@
|
|||||||
## Description
|
## Description
|
||||||
|
|
||||||
The `let` builtin command evaluates each supplied word from left to
|
The `let` builtin command evaluates each supplied word from left to
|
||||||
right as an [arithmetic expression](/syntax/arith_expr) and returns an
|
right as an [arithmetic expression](../../syntax/arith_expr.md) and returns an
|
||||||
exit code according to the truth value of the rightmost expression.
|
exit code according to the truth value of the rightmost expression.
|
||||||
|
|
||||||
- 0 (TRUE) when `arg` evaluated to not 0 (arithmetic \"true\")
|
- 0 (TRUE) when `arg` evaluated to not 0 (arithmetic \"true\")
|
||||||
- 1 (FALSE) when `arg` evaluated to 0 (arithmetic \"false\")
|
- 1 (FALSE) when `arg` evaluated to 0 (arithmetic \"false\")
|
||||||
|
|
||||||
For this return code mapping, please see [this
|
For this return code mapping, please see [this
|
||||||
section](/syntax/arith_expr#arithmetic_expressions_and_return_codes).
|
section](../../syntax/arith_expr.md#arithmetic_expressions_and_return_codes).
|
||||||
They work in the same way as `((`.
|
They work in the same way as `((`.
|
||||||
|
|
||||||
## Examples
|
## Examples
|
||||||
|
|
||||||
`let` is very similar to [((](/syntax/ccmd/arithmetic_eval) - the only
|
`let` is very similar to [((](../../syntax/ccmd/arithmetic_eval.md) - the only
|
||||||
difference being `let` is a builtin (simple command), and `((` is a
|
difference being `let` is a builtin (simple command), and `((` is a
|
||||||
compound command. The arguments to `let` are therefore subject to all
|
compound command. The arguments to `let` are therefore subject to all
|
||||||
the same expansions and substitutions as any other simple command -
|
the same expansions and substitutions as any other simple command -
|
||||||
requiring proper quoting and escaping - whereas the contents of `((`
|
requiring proper quoting and escaping - whereas the contents of `((`
|
||||||
aren\'t subject to [word-splitting](/syntax/expansion/wordsplit) or
|
aren\'t subject to [word-splitting](../../syntax/expansion/wordsplit.md) or
|
||||||
[pathname expansion](/syntax/expansion/globs) (almost never desirable
|
[pathname expansion](../../syntax/expansion/globs.md) (almost never desirable
|
||||||
for arithmetic). For this reason, **the [arithmetic compound
|
for arithmetic). For this reason, **the [arithmetic compound
|
||||||
command](/syntax/ccmd/arithmetic_eval) should generally be preferred
|
command](../../syntax/ccmd/arithmetic_eval.md) should generally be preferred
|
||||||
over `let`**.
|
over `let`**.
|
||||||
|
|
||||||
$ let 'b = a' "(a += 3) + $((a = 1)), b++"
|
$ let 'b = a' "(a += 3) + $((a = 1)), b++"
|
||||||
@ -35,7 +35,7 @@ over `let`**.
|
|||||||
4 - 2 - 0
|
4 - 2 - 0
|
||||||
|
|
||||||
Is equivalent to the [arithmetic evaluation compound
|
Is equivalent to the [arithmetic evaluation compound
|
||||||
command](/syntax/ccmd/arithmetic_eval):
|
command](../../syntax/ccmd/arithmetic_eval.md):
|
||||||
|
|
||||||
$ (( b = a, (a += 3) + $((a = 1)), b++ ))
|
$ (( b = a, (a += 3) + $((a = 1)), b++ ))
|
||||||
$ echo "$a - $b - $?"
|
$ echo "$a - $b - $?"
|
||||||
@ -78,14 +78,14 @@ needed.
|
|||||||
` Aside from differences in supported arithmetic features, this
|
` Aside from differences in supported arithmetic features, this
|
||||||
should be identical to the Bash/Ksh `let`.
|
should be identical to the Bash/Ksh `let`.
|
||||||
- It seems to be a common misunderstanding that `let` has some legacy
|
- It seems to be a common misunderstanding that `let` has some legacy
|
||||||
purpose. Both `let` and [[^1]](syntax/ccmd/arithmetic_eval) were
|
purpose. Both `let` and [[^1]](../../syntax/ccmd/arithmetic_eval.md) were
|
||||||
ksh88 features and almost identical in terms of portability as
|
ksh88 features and almost identical in terms of portability as
|
||||||
everything that inherited one also tended to get the other. Don\'t
|
everything that inherited one also tended to get the other. Don\'t
|
||||||
choose `let` over `((` expecting it to work in more places.
|
choose `let` over `((` expecting it to work in more places.
|
||||||
- [expr(1)](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/expr.html#tag_20_42)
|
- [expr(1)](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/expr.html#tag_20_42)
|
||||||
is a command one is likely to come across sooner or later. While it
|
is a command one is likely to come across sooner or later. While it
|
||||||
is more \"standard\" than `let`, the above should always be
|
is more \"standard\" than `let`, the above should always be
|
||||||
preferred. Both [arithmetic expansion](/syntax/arith_expr)s and the
|
preferred. Both [arithmetic expansion](../../syntax/arith_expr.md)s and the
|
||||||
`[` test operator are specified by POSIX(r) and satisfy almost all
|
`[` test operator are specified by POSIX(r) and satisfy almost all
|
||||||
of expr\'s use-cases. Unlike `let`, `expr` cannot assign directly to
|
of expr\'s use-cases. Unlike `let`, `expr` cannot assign directly to
|
||||||
bash variables but instead returns a result on stdout. `expr` takes
|
bash variables but instead returns a result on stdout. `expr` takes
|
||||||
@ -96,16 +96,16 @@ needed.
|
|||||||
without generating any output other than a return code.
|
without generating any output other than a return code.
|
||||||
- For unknown reasons, `let` is one of the Bash commands with special
|
- For unknown reasons, `let` is one of the Bash commands with special
|
||||||
parsing for arguments formatted like compound array assignments.
|
parsing for arguments formatted like compound array assignments.
|
||||||
See: [eval](commands/builtin/eval#portability_considerations) for
|
See: [eval](../../commands/builtin/eval.md#portability_considerations) for
|
||||||
details. There are no known practical uses for this. Parentheses are
|
details. There are no known practical uses for this. Parentheses are
|
||||||
treated as grouping operators and compound assignment is not
|
treated as grouping operators and compound assignment is not
|
||||||
possible by arithmetic expressions.
|
possible by arithmetic expressions.
|
||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [arithmetic expansion](/syntax/expansion/arith)
|
- Internal: [arithmetic expansion](../../syntax/expansion/arith.md)
|
||||||
- Internal: [arithmetic expressions](/syntax/arith_expr)
|
- Internal: [arithmetic expressions](../../syntax/arith_expr.md)
|
||||||
- Internal: [arithmetic evaluation compound
|
- Internal: [arithmetic evaluation compound
|
||||||
command](/syntax/ccmd/arithmetic_eval)
|
command](../../syntax/ccmd/arithmetic_eval.md)
|
||||||
|
|
||||||
[^1]: \...
|
[^1]: \...
|
||||||
|
@ -6,7 +6,7 @@
|
|||||||
|
|
||||||
## Description
|
## Description
|
||||||
|
|
||||||
`local` is identical to [declare](/commands/builtin/declare) in every
|
`local` is identical to [declare](../../commands/builtin/declare.md) in every
|
||||||
way, and takes all the same options, with 3 exceptions:
|
way, and takes all the same options, with 3 exceptions:
|
||||||
|
|
||||||
- Usage outside of a function is an error. Both `declare` and `local`
|
- Usage outside of a function is an error. Both `declare` and `local`
|
||||||
|
@ -215,7 +215,7 @@ each subsequent 2 iterations. The RETURN trap is unimportant.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [arrays](/syntax/arrays)
|
- [arrays](../../syntax/arrays.md)
|
||||||
- [read](/commands/builtin/read) - If you don\'t know about this yet,
|
- [read](../../commands/builtin/read.md) - If you don\'t know about this yet,
|
||||||
why are you reading this page?
|
why are you reading this page?
|
||||||
- <http://mywiki.wooledge.org/BashFAQ/001> - It\'s FAQ 1 for a reason.
|
- <http://mywiki.wooledge.org/BashFAQ/001> - It\'s FAQ 1 for a reason.
|
||||||
|
@ -10,7 +10,7 @@ nearly identical for an external command that follows POSIX(r).
|
|||||||
[GNU Awk](http://www.gnu.org/software/gawk/manual/gawk.html#Printf)
|
[GNU Awk](http://www.gnu.org/software/gawk/manual/gawk.html#Printf)
|
||||||
expects a comma after the format string and between each of the
|
expects a comma after the format string and between each of the
|
||||||
arguments of a **printf** command. For examples, see: [code
|
arguments of a **printf** command. For examples, see: [code
|
||||||
snippet](printf?&#using_printf_inside_of_awk). \</div\>
|
snippet](../../printf?&.md#using_printf_inside_of_awk). \</div\>
|
||||||
|
|
||||||
Unlike other documentations, I don\'t want to redirect you to the manual
|
Unlike other documentations, I don\'t want to redirect you to the manual
|
||||||
page for the `printf()` C function family. However, if you\'re more
|
page for the `printf()` C function family. However, if you\'re more
|
||||||
@ -68,8 +68,8 @@ this opens up the possibility of an easy code injection vulnerability.
|
|||||||
\...where the echo can of course be replaced with any arbitrary command.
|
\...where the echo can of course be replaced with any arbitrary command.
|
||||||
If you must, either specify a hard-coded format string or use \-- to
|
If you must, either specify a hard-coded format string or use \-- to
|
||||||
signal the end of options. The exact same issue also applies to
|
signal the end of options. The exact same issue also applies to
|
||||||
[read](commands/builtin/read), and a similar one to
|
[read](../../commands/builtin/read.md), and a similar one to
|
||||||
[mapfile](commands/builtin/mapfile), though performing expansions into
|
[mapfile](../../commands/builtin/mapfile.md), though performing expansions into
|
||||||
their arguments is less common. \</note\>
|
their arguments is less common. \</note\>
|
||||||
|
|
||||||
### Arguments
|
### Arguments
|
||||||
@ -93,9 +93,9 @@ interpreted. If fewer format specifiers than arguments are present, then
|
|||||||
number-formats are set to zero, while string-formats are set to null
|
number-formats are set to zero, while string-formats are set to null
|
||||||
(empty).
|
(empty).
|
||||||
|
|
||||||
Take care to avoid [word splitting](/syntax/expansion/wordsplit), as
|
Take care to avoid [word splitting](../../syntax/expansion/wordsplit.md), as
|
||||||
accidentally passing the wrong number of arguments can produce wildly
|
accidentally passing the wrong number of arguments can produce wildly
|
||||||
different and unexpected results. See [this article](/syntax/words).
|
different and unexpected results. See [this article](../../syntax/words.md).
|
||||||
|
|
||||||
\<note warning\> [**Again, attention:**]{.underline} When a numerical
|
\<note warning\> [**Again, attention:**]{.underline} When a numerical
|
||||||
format expects a number, the internal `printf`-command will use the
|
format expects a number, the internal `printf`-command will use the
|
||||||
@ -234,7 +234,7 @@ associated with a `%b` format:
|
|||||||
(POSIX specifies up to three).
|
(POSIX specifies up to three).
|
||||||
|
|
||||||
These are also respects in which `%b` differs from the escapes used by
|
These are also respects in which `%b` differs from the escapes used by
|
||||||
[\$\'\...\'](syntax/quoting#ansi_c_like_strings) style quoting.
|
[\$\'\...\'](../../syntax/quoting.md#ansi_c_like_strings) style quoting.
|
||||||
|
|
||||||
## Examples
|
## Examples
|
||||||
|
|
||||||
@ -447,7 +447,7 @@ fmt++;
|
|||||||
|
|
||||||
- The optional Bash loadable `print` may be useful for ksh
|
- The optional Bash loadable `print` may be useful for ksh
|
||||||
compatibility and to overcome some of
|
compatibility and to overcome some of
|
||||||
[echo](commands/builtin/echo)\'s portability pitfalls. Bash, ksh93,
|
[echo](../../commands/builtin/echo.md)\'s portability pitfalls. Bash, ksh93,
|
||||||
and zsh\'s `print` have an `-f` option which takes a `printf` format
|
and zsh\'s `print` have an `-f` option which takes a `printf` format
|
||||||
string and applies it to the remaining arguments. Bash lists the
|
string and applies it to the remaining arguments. Bash lists the
|
||||||
synopsis as:
|
synopsis as:
|
||||||
@ -461,7 +461,7 @@ fmt++;
|
|||||||
```
|
```
|
||||||
- Assigning to variables: The `printf -v` way is slightly different to
|
- Assigning to variables: The `printf -v` way is slightly different to
|
||||||
the way using command-substitution. [Command
|
the way using command-substitution. [Command
|
||||||
substitution](/syntax/expansion/cmdsubst) removes trailing newlines
|
substitution](../../syntax/expansion/cmdsubst.md) removes trailing newlines
|
||||||
before substituting the text, `printf -v` preserves all output.
|
before substituting the text, `printf -v` preserves all output.
|
||||||
|
|
||||||
## See also
|
## See also
|
||||||
@ -471,6 +471,6 @@ fmt++;
|
|||||||
and [printf()
|
and [printf()
|
||||||
function](http://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html)
|
function](http://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html)
|
||||||
- [Code snip: Print a horizontal
|
- [Code snip: Print a horizontal
|
||||||
line](/snipplets/print_horizontal_line) uses some `printf` examples
|
line](../../snipplets/print_horizontal_line.md) uses some `printf` examples
|
||||||
- [Greg\'s BashFAQ 18: How can I use numbers with leading zeros in a
|
- [Greg\'s BashFAQ 18: How can I use numbers with leading zeros in a
|
||||||
loop, e.g., 01, 02?](BashFAQ>018)
|
loop, e.g., 01, 02?](BashFAQ>018)
|
||||||
|
@ -16,13 +16,13 @@ Since Bash 4.3-alpha, `read` skips any `NUL` (ASCII code 0) characters
|
|||||||
in input.
|
in input.
|
||||||
|
|
||||||
If `<NAME...>` is given, the line is word-split using
|
If `<NAME...>` is given, the line is word-split using
|
||||||
[IFS](/syntax/shellvars#IFS) variable, and every word is assigned to one
|
[IFS](../../syntax/shellvars.md#IFS) variable, and every word is assigned to one
|
||||||
`<NAME>`. The remaining words are all assigned to the last `<NAME>` if
|
`<NAME>`. The remaining words are all assigned to the last `<NAME>` if
|
||||||
more words than variable names are present.
|
more words than variable names are present.
|
||||||
|
|
||||||
\<WRAP center round info 90%\> If no `<NAME>` is given, the whole line
|
\<WRAP center round info 90%\> If no `<NAME>` is given, the whole line
|
||||||
read (without performing word-splitting!) is assigned to the shell
|
read (without performing word-splitting!) is assigned to the shell
|
||||||
variable [REPLY](/syntax/shellvars#REPLY). Then, `REPLY` really contains
|
variable [REPLY](../../syntax/shellvars.md#REPLY). Then, `REPLY` really contains
|
||||||
the line as it was read, without stripping pre- and postfix spaces and
|
the line as it was read, without stripping pre- and postfix spaces and
|
||||||
other things!
|
other things!
|
||||||
|
|
||||||
@ -33,7 +33,7 @@ other things!
|
|||||||
\</WRAP\>
|
\</WRAP\>
|
||||||
|
|
||||||
If a timeout is given, or if the shell variable
|
If a timeout is given, or if the shell variable
|
||||||
[TMOUT](/syntax/shellvars#TMOUT) is set, it is counted from initially
|
[TMOUT](../../syntax/shellvars.md#TMOUT) is set, it is counted from initially
|
||||||
waiting for input until the completion of input (i.e. until the complete
|
waiting for input until the completion of input (i.e. until the complete
|
||||||
line is read). That means the timeout can occur during input, too.
|
line is read). That means the timeout can occur during input, too.
|
||||||
|
|
||||||
@ -64,7 +64,7 @@ Of course it\'s valid to set individual array elements without using
|
|||||||
\<WRAP center round important 90%\>
|
\<WRAP center round important 90%\>
|
||||||
|
|
||||||
Reading into array elements using the syntax above **may cause [pathname
|
Reading into array elements using the syntax above **may cause [pathname
|
||||||
expansion](/syntax/expansion/globs) to occur**.
|
expansion](../../syntax/expansion/globs.md) to occur**.
|
||||||
|
|
||||||
Example: You are in a directory with a file named `x1`, and you want to
|
Example: You are in a directory with a file named `x1`, and you want to
|
||||||
read into an array `x`, index `1` with
|
read into an array `x`, index `1` with
|
||||||
@ -172,7 +172,7 @@ Take care that you cannot use a pipe:
|
|||||||
Why? because the commands of the pipe run in subshells that cannot
|
Why? because the commands of the pipe run in subshells that cannot
|
||||||
modify the parent shell. As a result, the variables `col1`, `col2` and
|
modify the parent shell. As a result, the variables `col1`, `col2` and
|
||||||
`col3` of the parent shell are not modified (see article:
|
`col3` of the parent shell are not modified (see article:
|
||||||
[processtree](/scripting/processtree)).
|
[processtree](../../scripting/processtree.md)).
|
||||||
|
|
||||||
If the variable has more fields than there are variables, the last
|
If the variable has more fields than there are variables, the last
|
||||||
variable get the remaining of the line:
|
variable get the remaining of the line:
|
||||||
@ -184,7 +184,7 @@ variable get the remaining of the line:
|
|||||||
|
|
||||||
By default reads separates the line in fields using spaces or tabs. You
|
By default reads separates the line in fields using spaces or tabs. You
|
||||||
can modify this using the *special variable*
|
can modify this using the *special variable*
|
||||||
[IFS](/syntax/shellvars#IFS), the Internal Field Separator.
|
[IFS](../../syntax/shellvars.md#IFS), the Internal Field Separator.
|
||||||
|
|
||||||
IFS=":" read -r col1 col2 <<< "hello:world"
|
IFS=":" read -r col1 col2 <<< "hello:world"
|
||||||
printf "col1: %s col2: %s\n" "$col1" "$col2"
|
printf "col1: %s col2: %s\n" "$col1" "$col2"
|
||||||
@ -264,6 +264,6 @@ date/time string are recognized correctly.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [The printf builtin command](/commands/builtin/printf)
|
- Internal: [The printf builtin command](../../commands/builtin/printf.md)
|
||||||
|
|
||||||
[^1]: fixed in 4.2-rc1
|
[^1]: fixed in 4.2-rc1
|
||||||
|
@ -41,5 +41,5 @@ An argument of `--` disables further option processing.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [declare](/commands/builtin/declare)
|
- [declare](../../commands/builtin/declare.md)
|
||||||
- [unset](/commands/builtin/unset)
|
- [unset](../../commands/builtin/unset.md)
|
||||||
|
@ -31,5 +31,5 @@ comes back, there was a problem in doing the return.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [The exit builtin command](/commands/builtin/exit)
|
- [The exit builtin command](../../commands/builtin/exit.md)
|
||||||
- [The exit status](/dict/terms/exit_status)
|
- [The exit status](../../dict/terms/exit_status.md)
|
||||||
|
@ -11,7 +11,7 @@ FIXME incomplete - text, examples, maybe extended description
|
|||||||
`set` is primarily made to
|
`set` is primarily made to
|
||||||
|
|
||||||
- set the positional parameters (see [handling positional
|
- set the positional parameters (see [handling positional
|
||||||
parameters](/scripting/posparams)) to `<POSPARAMS>`
|
parameters](../../scripting/posparams.md)) to `<POSPARAMS>`
|
||||||
- set shell attributes with short options (see below)
|
- set shell attributes with short options (see below)
|
||||||
- set shell attributes with long option names (see below)
|
- set shell attributes with long option names (see below)
|
||||||
|
|
||||||
@ -29,7 +29,7 @@ set flags (true for most commands on UNIX(r)).
|
|||||||
`-a` `allexport` Automatically mark new and altered variables to be exported to subsequent environments.
|
`-a` `allexport` Automatically mark new and altered variables to be exported to subsequent environments.
|
||||||
`-b` `notify` Don\'t wait for the next prompt to print when showing the reports for a terminated background job (only with job control)
|
`-b` `notify` Don\'t wait for the next prompt to print when showing the reports for a terminated background job (only with job control)
|
||||||
`-e` `errexit` When set, the shell exits when a simple command in a command list exits non-zero (`FALSE`). This is not done in situations, where the exit code is already checked (`if`, `while`, `until`, `||`, `&&`)
|
`-e` `errexit` When set, the shell exits when a simple command in a command list exits non-zero (`FALSE`). This is not done in situations, where the exit code is already checked (`if`, `while`, `until`, `||`, `&&`)
|
||||||
`-f` `noglob` Disable [pathname expansion](/syntax/expansion/globs) (globbing)
|
`-f` `noglob` Disable [pathname expansion](../../syntax/expansion/globs.md) (globbing)
|
||||||
`-h` `hashall` Remembers the location of commands when they\'re called (hashing). Enabled by default.
|
`-h` `hashall` Remembers the location of commands when they\'re called (hashing). Enabled by default.
|
||||||
`-k` `keyword` Allows to place environment-assignments everywhere in the commandline, not only infront of the called command.
|
`-k` `keyword` Allows to place environment-assignments everywhere in the commandline, not only infront of the called command.
|
||||||
`-m` `monitor` **Monitor mode**. With job control, a short descriptive line is printed when a backgroud job ends. Default is \"on\" for interactive shells (with job control).
|
`-m` `monitor` **Monitor mode**. With job control, a short descriptive line is printed when a backgroud job ends. Default is \"on\" for interactive shells (with job control).
|
||||||
@ -40,8 +40,8 @@ set flags (true for most commands on UNIX(r)).
|
|||||||
`-u` `nounset` Treat unset variables as an error when performing parameter expansion. Non-interactive shells exit on this error.
|
`-u` `nounset` Treat unset variables as an error when performing parameter expansion. Non-interactive shells exit on this error.
|
||||||
`-v` `verbose` Print shell input lines as they are read - useful for debugging.
|
`-v` `verbose` Print shell input lines as they are read - useful for debugging.
|
||||||
`-x` `xtrace` Print commands just before execution - with all expansions and substitutions done, and words marked - useful for debugging.
|
`-x` `xtrace` Print commands just before execution - with all expansions and substitutions done, and words marked - useful for debugging.
|
||||||
`-B` `braceexpand` The shell performs [brace expansion](/syntax/expansion/brace) This is on by default.
|
`-B` `braceexpand` The shell performs [brace expansion](../../syntax/expansion/brace.md) This is on by default.
|
||||||
`-C` \<BOOKMARK:tag_noclobber\>`noclobber` Don\'t overwrite files on redirection operations. You can override that by specifying the `>|` redirection operator when needed. See [redirection](/syntax/redirection)
|
`-C` \<BOOKMARK:tag_noclobber\>`noclobber` Don\'t overwrite files on redirection operations. You can override that by specifying the `>|` redirection operator when needed. See [redirection](../../syntax/redirection.md)
|
||||||
`-E` `errtrace` `ERR`-traps are inherited by by shell functions, command substitutions, and commands executed in a subshell environment.
|
`-E` `errtrace` `ERR`-traps are inherited by by shell functions, command substitutions, and commands executed in a subshell environment.
|
||||||
`-H` `histexpand` Enable `!`-style history expansion. Defaults to `on` for interactive shells.
|
`-H` `histexpand` Enable `!`-style history expansion. Defaults to `on` for interactive shells.
|
||||||
`-P` `physical` Don\'t follow symlinks when changing directories - use the physical filesystem structure.
|
`-P` `physical` Don\'t follow symlinks when changing directories - use the physical filesystem structure.
|
||||||
@ -51,7 +51,7 @@ set flags (true for most commands on UNIX(r)).
|
|||||||
Long options usable with `-o` without a short equivalent
|
Long options usable with `-o` without a short equivalent
|
||||||
`emacs` Use an emacs-style command line editing interface. This is enabled by default when the shell is interactive, unless the shell is started with `--noediting` option.
|
`emacs` Use an emacs-style command line editing interface. This is enabled by default when the shell is interactive, unless the shell is started with `--noediting` option.
|
||||||
`history` If set, command historization is done (enabled by default on interactive shells)
|
`history` If set, command historization is done (enabled by default on interactive shells)
|
||||||
`ignoreeof` The effect is as if the shell command `IGNOREEOF=10` had been executed. See [shell variables](/syntax/shellvars).
|
`ignoreeof` The effect is as if the shell command `IGNOREEOF=10` had been executed. See [shell variables](../../syntax/shellvars.md).
|
||||||
`nolog` **(currently ignored)**
|
`nolog` **(currently ignored)**
|
||||||
`pipefail` If set, the exit code from a pipeline is different from the normal (\"last command in pipeline\") behaviour: `TRUE` when no command failed, `FALSE` when something failed (code of the rightmost command that failed)
|
`pipefail` If set, the exit code from a pipeline is different from the normal (\"last command in pipeline\") behaviour: `TRUE` when no command failed, `FALSE` when something failed (code of the rightmost command that failed)
|
||||||
`posix` When set, Bash runs in POSIX mode.
|
`posix` When set, Bash runs in POSIX mode.
|
||||||
@ -78,4 +78,4 @@ naturally.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [The shopt builtin command](/commands/builtin/shopt)
|
- Internal: [The shopt builtin command](../../commands/builtin/shopt.md)
|
||||||
|
@ -28,7 +28,7 @@ When you use `shift 1`, they will be changed to:
|
|||||||
2 a
|
2 a
|
||||||
3 test
|
3 test
|
||||||
|
|
||||||
The [special parameter](/syntax/shellvars#special_parameters) `$#` will
|
The [special parameter](../../syntax/shellvars.md#special_parameters) `$#` will
|
||||||
reflect the final number of positional parameters.
|
reflect the final number of positional parameters.
|
||||||
|
|
||||||
If the number given is 0, no changes are made to the positional
|
If the number given is 0, no changes are made to the positional
|
||||||
@ -56,13 +56,13 @@ There are no options.
|
|||||||
than the number of positional parameters. **POSIX does not require
|
than the number of positional parameters. **POSIX does not require
|
||||||
that behavior**. Bash (even in POSIX mode) and Zsh return 1 when
|
that behavior**. Bash (even in POSIX mode) and Zsh return 1 when
|
||||||
there are no args, and no error output is produced unless the
|
there are no args, and no error output is produced unless the
|
||||||
[shift_verbose](internals/shell_options#shift_verbose)
|
[shift_verbose](../../internals/shell_options.md#shift_verbose)
|
||||||
[shopt](commands/builtin/shopt) option is enabled. Ksh93, pdksh,
|
[shopt](../../commands/builtin/shopt.md) option is enabled. Ksh93, pdksh,
|
||||||
posh, mksh, and dash, all throw useless fatal shell
|
posh, mksh, and dash, all throw useless fatal shell
|
||||||
errors.`$ dash -c 'f() { if shift; then echo "$1"; else echo "no args"; fi; }; f'
|
errors.`$ dash -c 'f() { if shift; then echo "$1"; else echo "no args"; fi; }; f'
|
||||||
dash: 1: shift: can't shift that many
|
dash: 1: shift: can't shift that many
|
||||||
` In most shells, you can work around this problem using the
|
` In most shells, you can work around this problem using the
|
||||||
[command](/commands/builtin/command) builtin to suppress fatal
|
[command](../../commands/builtin/command.md) builtin to suppress fatal
|
||||||
errors caused by *special builtins*. \<code\> \$ dash -c \'f() { if
|
errors caused by *special builtins*. \<code\> \$ dash -c \'f() { if
|
||||||
command shift 2\>/dev/null; then echo \"\$1\"; else echo \"no
|
command shift 2\>/dev/null; then echo \"\$1\"; else echo \"no
|
||||||
args\"; fi; }; f\'
|
args\"; fi; }; f\'
|
||||||
|
@ -1,6 +1,6 @@
|
|||||||
# The shopt builtin command
|
# The shopt builtin command
|
||||||
|
|
||||||
The `shopt` builtin manages [shell options](/internals/shell_options), a
|
The `shopt` builtin manages [shell options](../../internals/shell_options.md), a
|
||||||
set of boolean (`on`/`off`) configuration variables that control the
|
set of boolean (`on`/`off`) configuration variables that control the
|
||||||
behaviour of the shell.
|
behaviour of the shell.
|
||||||
|
|
||||||
@ -11,13 +11,13 @@ behaviour of the shell.
|
|||||||
## Description
|
## Description
|
||||||
|
|
||||||
Note: Some of these options and other shell options can also be set with
|
Note: Some of these options and other shell options can also be set with
|
||||||
[the set builtin](/commands/builtin/set).
|
[the set builtin](../../commands/builtin/set.md).
|
||||||
|
|
||||||
### Options
|
### Options
|
||||||
|
|
||||||
Option Description
|
Option Description
|
||||||
-------- -----------------------------------------------------------------------------------------------------------------------------
|
-------- -----------------------------------------------------------------------------------------------------------------------------
|
||||||
`-o` Restrict the values of `<OPTNAME...>` to only those also known by [the set builtin](/commands/builtin/set)
|
`-o` Restrict the values of `<OPTNAME...>` to only those also known by [the set builtin](../../commands/builtin/set.md)
|
||||||
`-p` Print all shell options and their current value. **Default**.
|
`-p` Print all shell options and their current value. **Default**.
|
||||||
`-q` Quiet mode. Set exit code if named option is set. For multiple options: `TRUE` if all options are set, `FALSE` otherwise
|
`-q` Quiet mode. Set exit code if named option is set. For multiple options: `TRUE` if all options are set, `FALSE` otherwise
|
||||||
`-s` Enable ([s]{.underline}et) the shell options named by `<OPTNAME...>` or list all *enabled* options if no names are given
|
`-s` Enable ([s]{.underline}et) the shell options named by `<OPTNAME...>` or list all *enabled* options if no names are given
|
||||||
@ -47,5 +47,5 @@ The `shopt` command is not portable accross different shells.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [The set builtin command](/commands/builtin/set)
|
- Internal: [The set builtin command](../../commands/builtin/set.md)
|
||||||
- Internal: [List of shell options](/internals/shell_options)
|
- Internal: [List of shell options](../../internals/shell_options.md)
|
||||||
|
@ -34,7 +34,7 @@ Special events
|
|||||||
`EXIT` 0 executed on shell exit
|
`EXIT` 0 executed on shell exit
|
||||||
`DEBUG` executed before every simple command
|
`DEBUG` executed before every simple command
|
||||||
`RETURN` executed when a shell function or a sourced code finishes executing
|
`RETURN` executed when a shell function or a sourced code finishes executing
|
||||||
`ERR` executed each time a command\'s failure would cause the shell to exit when the [`-e` option (`errexit`)](/commands/builtin/set) is enabled
|
`ERR` executed each time a command\'s failure would cause the shell to exit when the [`-e` option (`errexit`)](../../commands/builtin/set.md) is enabled
|
||||||
|
|
||||||
### Options
|
### Options
|
||||||
|
|
||||||
@ -68,5 +68,5 @@ Special events
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [the set command](/commands/builtin/set) for the `-e` (`errexit`)
|
- [the set command](../../commands/builtin/set.md) for the `-e` (`errexit`)
|
||||||
option
|
option
|
||||||
|
@ -175,7 +175,7 @@ using `unset`. Also, I prefer it as a matter of style.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [declare](/commands/builtin/declare)
|
- [declare](../../commands/builtin/declare.md)
|
||||||
- [unset](/commands/builtin/unset)
|
- [unset](../../commands/builtin/unset.md)
|
||||||
- [POSIX `unset`
|
- [POSIX `unset`
|
||||||
utility](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_29)
|
utility](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_29)
|
||||||
|
@ -6,17 +6,17 @@
|
|||||||
|
|
||||||
## Description
|
## Description
|
||||||
|
|
||||||
This command evaluates the [arithmetic expression](/syntax/arith_expr)
|
This command evaluates the [arithmetic expression](../../syntax/arith_expr.md)
|
||||||
`<EXPRESSION>`.
|
`<EXPRESSION>`.
|
||||||
|
|
||||||
If the expression evaluates to 0 then the exit code of the expression is
|
If the expression evaluates to 0 then the exit code of the expression is
|
||||||
set to 1 (`FALSE`). If the expression evaluates to something else than
|
set to 1 (`FALSE`). If the expression evaluates to something else than
|
||||||
0, then the exit code of the expression is set to 0 (`TRUE`). For this
|
0, then the exit code of the expression is set to 0 (`TRUE`). For this
|
||||||
return code mapping, please see [this
|
return code mapping, please see [this
|
||||||
section](/syntax/arith_expr#arithmetic_expressions_and_return_codes).
|
section](../../syntax/arith_expr.md#arithmetic_expressions_and_return_codes).
|
||||||
|
|
||||||
The functionality basically is equivalent to what the [`let` builtin
|
The functionality basically is equivalent to what the [`let` builtin
|
||||||
command](/commands/builtin/let) does. The arithmetic evaluation compound
|
command](../../commands/builtin/let.md) does. The arithmetic evaluation compound
|
||||||
command should be preferred.
|
command should be preferred.
|
||||||
|
|
||||||
## Examples
|
## Examples
|
||||||
@ -25,6 +25,6 @@ command should be preferred.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [arithmetic expressions](/syntax/arith_expr)
|
- Internal: [arithmetic expressions](../../syntax/arith_expr.md)
|
||||||
- Internal: [arithmetic expansion](/syntax/expansion/arith)
|
- Internal: [arithmetic expansion](../../syntax/expansion/arith.md)
|
||||||
- Internal: [The `let` builtin command](/commands/builtin/let)
|
- Internal: [The `let` builtin command](../../commands/builtin/let.md)
|
||||||
|
@ -19,7 +19,7 @@
|
|||||||
## Description
|
## Description
|
||||||
|
|
||||||
The C-style for-loop is a [compound
|
The C-style for-loop is a [compound
|
||||||
command](syntax/basicgrammar#compound_commands) derived from the
|
command](../../syntax/basicgrammar.md#compound_commands) derived from the
|
||||||
equivalent ksh88 feature, which is in turn derived from the C \"for\"
|
equivalent ksh88 feature, which is in turn derived from the C \"for\"
|
||||||
keyword. Its purpose is to provide a convenient way to evaluate
|
keyword. Its purpose is to provide a convenient way to evaluate
|
||||||
arithmetic expressions in a loop, plus initialize any required
|
arithmetic expressions in a loop, plus initialize any required
|
||||||
@ -27,9 +27,9 @@ arithmetic variables. It is one of the main \"loop with a counter\"
|
|||||||
mechanisms available in the language.
|
mechanisms available in the language.
|
||||||
|
|
||||||
The `((;;))` syntax at the top of the loop is not an ordinary
|
The `((;;))` syntax at the top of the loop is not an ordinary
|
||||||
[arithmetic compound command](syntax/ccmd/arithmetic_eval), but is part
|
[arithmetic compound command](../../syntax/ccmd/arithmetic_eval.md), but is part
|
||||||
of the C-style for-loop\'s own syntax. The three sections separated by
|
of the C-style for-loop\'s own syntax. The three sections separated by
|
||||||
semicolons are [arithmetic expression](/syntax/arith_expr) contexts.
|
semicolons are [arithmetic expression](../../syntax/arith_expr.md) contexts.
|
||||||
Each time one of the sections is to be evaluated, the section is first
|
Each time one of the sections is to be evaluated, the section is first
|
||||||
processed for: brace, parameter, command, arithmetic, and process
|
processed for: brace, parameter, command, arithmetic, and process
|
||||||
substitution/expansion as usual for arithmetic contexts. When the loop
|
substitution/expansion as usual for arithmetic contexts. When the loop
|
||||||
@ -51,16 +51,16 @@ behaves as if it would be 1 (**TRUE** in arithmetic context).
|
|||||||
:!: Like all loops (Both types of `for`-loop, `while` and `until`), this
|
:!: Like all loops (Both types of `for`-loop, `while` and `until`), this
|
||||||
loop can be:
|
loop can be:
|
||||||
|
|
||||||
- Terminated (broken) by the [break](commands/builtin/continuebreak)
|
- Terminated (broken) by the [break](../../commands/builtin/continuebreak.md)
|
||||||
builtin, optionally as `break N` to break out of `N` levels of
|
builtin, optionally as `break N` to break out of `N` levels of
|
||||||
nested loops.
|
nested loops.
|
||||||
- Forced immediately to the next iteration using the
|
- Forced immediately to the next iteration using the
|
||||||
[continue](commands/builtin/continuebreak) builtin, optionally as
|
[continue](../../commands/builtin/continuebreak.md) builtin, optionally as
|
||||||
the `continue N` analog to `break N`.
|
the `continue N` analog to `break N`.
|
||||||
|
|
||||||
The equivalent construct using a [while loop](syntax/ccmd/while_loop)
|
The equivalent construct using a [while loop](../../syntax/ccmd/while_loop.md)
|
||||||
and the [arithmetic expression compound
|
and the [arithmetic expression compound
|
||||||
command](/syntax/ccmd/arithmetic_eval) would be structured as:
|
command](../../syntax/ccmd/arithmetic_eval.md) would be structured as:
|
||||||
|
|
||||||
(( <EXPR1> ))
|
(( <EXPR1> ))
|
||||||
while (( <EXPR2> )); do
|
while (( <EXPR2> )); do
|
||||||
@ -70,7 +70,7 @@ command](/syntax/ccmd/arithmetic_eval) would be structured as:
|
|||||||
|
|
||||||
The equivalent `while` construct isn\'t exactly the same, because both,
|
The equivalent `while` construct isn\'t exactly the same, because both,
|
||||||
the `for` and the `while` loop behave differently in case you use the
|
the `for` and the `while` loop behave differently in case you use the
|
||||||
[continue](commands/builtin/continuebreak) command.
|
[continue](../../commands/builtin/continuebreak.md) command.
|
||||||
|
|
||||||
### Alternate syntax
|
### Alternate syntax
|
||||||
|
|
||||||
@ -87,7 +87,7 @@ This syntax is **not documented** and shouldn\'t be used. I found the
|
|||||||
parser definitions for it in 1.x code, and in modern 4.x code. My guess
|
parser definitions for it in 1.x code, and in modern 4.x code. My guess
|
||||||
is that it\'s there for compatibility reasons. Unlike the other
|
is that it\'s there for compatibility reasons. Unlike the other
|
||||||
aforementioned shells, Bash does not support the analogous syntax for
|
aforementioned shells, Bash does not support the analogous syntax for
|
||||||
[case..esac](syntax/ccmd/case#portability_considerations).
|
[case..esac](../../syntax/ccmd/case.md#portability_considerations).
|
||||||
|
|
||||||
### Return status
|
### Return status
|
||||||
|
|
||||||
@ -234,6 +234,6 @@ variables.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [Arithmetic expressions](/syntax/arith_expr)
|
- Internal: [Arithmetic expressions](../../syntax/arith_expr.md)
|
||||||
- Internal: [The classic for-loop](/syntax/ccmd/classic_for)
|
- Internal: [The classic for-loop](../../syntax/ccmd/classic_for.md)
|
||||||
- Internal: [The while-loop](/syntax/ccmd/while_loop)
|
- Internal: [The while-loop](../../syntax/ccmd/while_loop.md)
|
||||||
|
@ -13,9 +13,9 @@
|
|||||||
## Description
|
## Description
|
||||||
|
|
||||||
The `case`-statement can execute commands based on a [pattern
|
The `case`-statement can execute commands based on a [pattern
|
||||||
matching](/syntax/pattern) decision. The word `<WORD>` is matched
|
matching](../../syntax/pattern.md) decision. The word `<WORD>` is matched
|
||||||
against every pattern `<PATTERNn>` and on a match, the associated
|
against every pattern `<PATTERNn>` and on a match, the associated
|
||||||
[list](/syntax/basicgrammar#lists) `<LISTn>` is executed. Every
|
[list](../../syntax/basicgrammar.md#lists) `<LISTn>` is executed. Every
|
||||||
commandlist is terminated by `;;`. This rule is optional for the very
|
commandlist is terminated by `;;`. This rule is optional for the very
|
||||||
last commandlist (i.e., you can omit the `;;` before the `esac`). Every
|
last commandlist (i.e., you can omit the `;;` before the `esac`). Every
|
||||||
`<PATTERNn>` is separated from it\'s associated `<LISTn>` by a `)`, and
|
`<PATTERNn>` is separated from it\'s associated `<LISTn>` by a `)`, and
|
||||||
@ -43,7 +43,7 @@ done**, which means you can leave expansions unquoted without problems:
|
|||||||
esac
|
esac
|
||||||
|
|
||||||
This is similar to the behavior of the [conditional expression command
|
This is similar to the behavior of the [conditional expression command
|
||||||
(\"new test command\")](/syntax/ccmd/conditional_expression) (also no
|
(\"new test command\")](../../syntax/ccmd/conditional_expression.md) (also no
|
||||||
word splitting for expansions).
|
word splitting for expansions).
|
||||||
|
|
||||||
Unlike the C-case-statement, only the matching list and nothing else is
|
Unlike the C-case-statement, only the matching list and nothing else is
|
||||||
@ -152,7 +152,7 @@ f a b c
|
|||||||
- ksh93, mksh, zsh, and posh support a historical syntax where open
|
- ksh93, mksh, zsh, and posh support a historical syntax where open
|
||||||
and close braces may be used in place of `in` and `esac`:
|
and close braces may be used in place of `in` and `esac`:
|
||||||
`case word { x) ...; };`. This is similar to the alternate form Bash
|
`case word { x) ...; };`. This is similar to the alternate form Bash
|
||||||
supports for its [for loops](syntax/ccmd/classic_for), but Bash
|
supports for its [for loops](../../syntax/ccmd/classic_for.md), but Bash
|
||||||
doesn\'t support this syntax for `case..esac`.
|
doesn\'t support this syntax for `case..esac`.
|
||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
@ -66,7 +66,7 @@ The return status is the one of the last command executed in `<LIST>` or
|
|||||||
|
|
||||||
### Iterate over array elements
|
### Iterate over array elements
|
||||||
|
|
||||||
With some array syntax (see [arrays](/syntax/arrays)) you can easily
|
With some array syntax (see [arrays](../../syntax/arrays.md)) you can easily
|
||||||
\"feed\" the for-loop to iterate over all elements in an array (by
|
\"feed\" the for-loop to iterate over all elements in an array (by
|
||||||
mass-expanding all elements):
|
mass-expanding all elements):
|
||||||
|
|
||||||
@ -88,7 +88,7 @@ done
|
|||||||
### List positional parameters
|
### List positional parameters
|
||||||
|
|
||||||
You can use this
|
You can use this
|
||||||
[function](/syntax/basicgrammar#shell_function_definitions) to test how
|
[function](../../syntax/basicgrammar.md#shell_function_definitions) to test how
|
||||||
arguments to a command will be interpreted and parsed, and finally used:
|
arguments to a command will be interpreted and parsed, and finally used:
|
||||||
|
|
||||||
``` bash
|
``` bash
|
||||||
@ -138,7 +138,7 @@ done
|
|||||||
This is just an example. In *general*
|
This is just an example. In *general*
|
||||||
|
|
||||||
- it\'s not a good idea to parse `ls(1)` output
|
- it\'s not a good idea to parse `ls(1)` output
|
||||||
- the [while loop](/syntax/ccmd/while_loop) (using the `read` command)
|
- the [while loop](../../syntax/ccmd/while_loop.md) (using the `read` command)
|
||||||
is a better joice to iterate over lines
|
is a better joice to iterate over lines
|
||||||
|
|
||||||
### Nested for-loops
|
### Nested for-loops
|
||||||
@ -157,7 +157,7 @@ done
|
|||||||
### Loop over a number range
|
### Loop over a number range
|
||||||
|
|
||||||
Beginning in Bash 4, you can also use \"sequence expression\" form of
|
Beginning in Bash 4, you can also use \"sequence expression\" form of
|
||||||
[brace expansion](/syntax/expansion/brace) syntax when looping over
|
[brace expansion](../../syntax/expansion/brace.md) syntax when looping over
|
||||||
numbers, and this form does not create leading zeroes unless you ask for
|
numbers, and this form does not create leading zeroes unless you ask for
|
||||||
them:
|
them:
|
||||||
|
|
||||||
@ -183,6 +183,6 @@ expands to a huge list.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [c_for](/syntax/ccmd/c_for)
|
- [c_for](../../syntax/ccmd/c_for.md)
|
||||||
|
|
||||||
[^1]: <http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xcu_chap02.html#tag_23_02_09_12>
|
[^1]: <http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xcu_chap02.html#tag_23_02_09_12>
|
||||||
|
@ -7,13 +7,13 @@
|
|||||||
## Description
|
## Description
|
||||||
|
|
||||||
The conditional expression is meant as the modern variant of the
|
The conditional expression is meant as the modern variant of the
|
||||||
[classic test command](/commands/classictest). Since it is **not** a
|
[classic test command](../../commands/classictest.md). Since it is **not** a
|
||||||
normal command, Bash doesn\'t need to apply the normal commandline
|
normal command, Bash doesn\'t need to apply the normal commandline
|
||||||
parsing rules like recognizing `&&` as [command
|
parsing rules like recognizing `&&` as [command
|
||||||
list](/syntax/basicgrammar#lists) operator.
|
list](../../syntax/basicgrammar.md#lists) operator.
|
||||||
|
|
||||||
The testing features basically are the same (see the lists for [classic
|
The testing features basically are the same (see the lists for [classic
|
||||||
test command](/commands/classictest)), with some additions and
|
test command](../../commands/classictest.md)), with some additions and
|
||||||
extensions.
|
extensions.
|
||||||
|
|
||||||
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
||||||
@ -34,14 +34,14 @@ extensions.
|
|||||||
|
|
||||||
`<STRING> =~ <ERE>` `<STRING>` is checked against the [extended regular expression](https://en.wikipedia.org/wiki/Regular_expression#POSIX_extended) `<ERE>` - `TRUE` on a match
|
`<STRING> =~ <ERE>` `<STRING>` is checked against the [extended regular expression](https://en.wikipedia.org/wiki/Regular_expression#POSIX_extended) `<ERE>` - `TRUE` on a match
|
||||||
|
|
||||||
See the [classic test operators](/commands/classictest#file_tests) Do **not** use the `test`-typical operators `-a` and `-o` for AND and OR.
|
See the [classic test operators](../../commands/classictest.md#file_tests) Do **not** use the `test`-typical operators `-a` and `-o` for AND and OR.
|
||||||
|
|
||||||
See also [arithmetic comparisons](/syntax/arith_expr#comparisons) Using `(( <EXPRESSION> ))`, the [arithmetic expression compound command](/syntax/ccmd/arithmetic_eval)
|
See also [arithmetic comparisons](../../syntax/arith_expr.md#comparisons) Using `(( <EXPRESSION> ))`, the [arithmetic expression compound command](../../syntax/ccmd/arithmetic_eval.md)
|
||||||
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
||||||
|
|
||||||
When the `==` and `!=` operators are used, the string to the right of
|
When the `==` and `!=` operators are used, the string to the right of
|
||||||
the operator is considered a pattern and matched according to the rules
|
the operator is considered a pattern and matched according to the rules
|
||||||
of [Pattern Matching](/syntax/pattern). If the shell option
|
of [Pattern Matching](../../syntax/pattern.md). If the shell option
|
||||||
`nocasematch` is enabled, the match is performed without regard to the
|
`nocasematch` is enabled, the match is performed without regard to the
|
||||||
case of alphabetic characters.
|
case of alphabetic characters.
|
||||||
|
|
||||||
@ -65,8 +65,8 @@ operators `&&` and `||`.
|
|||||||
|
|
||||||
### Word splitting
|
### Word splitting
|
||||||
|
|
||||||
[Word splitting](/syntax/expansion/wordsplit) and [pathname
|
[Word splitting](../../syntax/expansion/wordsplit.md) and [pathname
|
||||||
expansion](/syntax/expansion/globs) are not performed in the expression
|
expansion](../../syntax/expansion/globs.md) are not performed in the expression
|
||||||
you give. That means, a variable containing spaces can be used without
|
you give. That means, a variable containing spaces can be used without
|
||||||
quoting:
|
quoting:
|
||||||
|
|
||||||
@ -78,7 +78,7 @@ quoting:
|
|||||||
echo "Sorry, no match :-("
|
echo "Sorry, no match :-("
|
||||||
fi
|
fi
|
||||||
|
|
||||||
Compare that to the [classic test command](/commands/classictest), where
|
Compare that to the [classic test command](../../commands/classictest.md), where
|
||||||
word splitting is done (because it\'s a normal command, not something
|
word splitting is done (because it\'s a normal command, not something
|
||||||
special):
|
special):
|
||||||
|
|
||||||
@ -128,7 +128,7 @@ regular expressions.
|
|||||||
|
|
||||||
The interpretation of quoted regular expression special characters can
|
The interpretation of quoted regular expression special characters can
|
||||||
be influenced by setting the `compat31` and `compat32` shell options
|
be influenced by setting the `compat31` and `compat32` shell options
|
||||||
(`compat*` in general). See [shell_options](/internals/shell_options).
|
(`compat*` in general). See [shell_options](../../internals/shell_options.md).
|
||||||
|
|
||||||
#### The special BASH_REMATCH array variable
|
#### The special BASH_REMATCH array variable
|
||||||
|
|
||||||
@ -139,7 +139,7 @@ The element with index 0 is the portion of the string matching the
|
|||||||
entire regular expression. The element with index n is the portion of
|
entire regular expression. The element with index n is the portion of
|
||||||
the string matching the nth parenthesized subexpression.
|
the string matching the nth parenthesized subexpression.
|
||||||
|
|
||||||
See [BASH_REMATCH](syntax/shellvars#bash_rematch).
|
See [BASH_REMATCH](../../syntax/shellvars.md#bash_rematch).
|
||||||
|
|
||||||
Example:
|
Example:
|
||||||
|
|
||||||
@ -203,9 +203,9 @@ both contains whitespace and is not the result of an expansion.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [pattern matching language](/syntax/pattern)
|
- Internal: [pattern matching language](../../syntax/pattern.md)
|
||||||
- Internal: [the classic test command](/commands/classictest)
|
- Internal: [the classic test command](../../commands/classictest.md)
|
||||||
- Internal: [the if-clause](/syntax/ccmd/if_clause)
|
- Internal: [the if-clause](../../syntax/ccmd/if_clause.md)
|
||||||
- [What is the difference between test, \[ and \[\[
|
- [What is the difference between test, \[ and \[\[
|
||||||
?](http://mywiki.wooledge.org/BashFAQ/031) - BashFAQ 31 - Greg\'s
|
?](http://mywiki.wooledge.org/BashFAQ/031) - BashFAQ 31 - Greg\'s
|
||||||
wiki.
|
wiki.
|
||||||
|
@ -10,14 +10,14 @@
|
|||||||
|
|
||||||
## Description
|
## Description
|
||||||
|
|
||||||
The [list](/syntax/basicgrammar#lists) `<LIST>` is simply executed in
|
The [list](../../syntax/basicgrammar.md#lists) `<LIST>` is simply executed in
|
||||||
the **current** shell environment. The list must be terminated with a
|
the **current** shell environment. The list must be terminated with a
|
||||||
**newline** or **semicolon**. For parsing reasons, the curly braces must
|
**newline** or **semicolon**. For parsing reasons, the curly braces must
|
||||||
be separated from `<LIST>` by a **semicolon** and **blanks** if they\'re
|
be separated from `<LIST>` by a **semicolon** and **blanks** if they\'re
|
||||||
in the same line! [^1][^2]
|
in the same line! [^1][^2]
|
||||||
|
|
||||||
This is known as a **group command**. The return status is the [exit
|
This is known as a **group command**. The return status is the [exit
|
||||||
status (exit code)](/scripting/basics#exit_codes) of the list.
|
status (exit code)](../../scripting/basics.md#exit_codes) of the list.
|
||||||
|
|
||||||
The input and output **filedescriptors** are cumulative:
|
The input and output **filedescriptors** are cumulative:
|
||||||
|
|
||||||
@ -30,7 +30,7 @@ The input and output **filedescriptors** are cumulative:
|
|||||||
} >output.txt
|
} >output.txt
|
||||||
|
|
||||||
This compound command also usually is the body of a [function
|
This compound command also usually is the body of a [function
|
||||||
definition](/syntax/basicgrammar#shell_function_definitions), though not
|
definition](../../syntax/basicgrammar.md#shell_function_definitions), though not
|
||||||
the only compound command that\'s valid there:
|
the only compound command that\'s valid there:
|
||||||
|
|
||||||
print_help() {
|
print_help() {
|
||||||
|
@ -6,7 +6,7 @@
|
|||||||
|
|
||||||
## Description
|
## Description
|
||||||
|
|
||||||
The [list](/syntax/basicgrammar#lists) `<LIST>` is executed in a
|
The [list](../../syntax/basicgrammar.md#lists) `<LIST>` is executed in a
|
||||||
separate shell - a subprocess. No changes to the environment (variables
|
separate shell - a subprocess. No changes to the environment (variables
|
||||||
etc\...) are reflected in the \"main shell\".
|
etc\...) are reflected in the \"main shell\".
|
||||||
|
|
||||||
@ -31,5 +31,5 @@ echo "$PWD" # Still in the original directory.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [grouping commands](/syntax/ccmd/grouping_plain)
|
- [grouping commands](../../syntax/ccmd/grouping_plain.md)
|
||||||
- [Subshells on Greycat\'s wiki](http://mywiki.wooledge.org/SubShell)
|
- [Subshells on Greycat\'s wiki](http://mywiki.wooledge.org/SubShell)
|
||||||
|
@ -26,10 +26,10 @@ The `if`-clause can control the script\'s flow (what\'s executed) by
|
|||||||
looking at the exit codes of other commands.
|
looking at the exit codes of other commands.
|
||||||
|
|
||||||
All commandsets `<LIST>` are interpreted as [command
|
All commandsets `<LIST>` are interpreted as [command
|
||||||
lists](/syntax/basicgrammar#lists), thus they can contain the whole
|
lists](../../syntax/basicgrammar.md#lists), thus they can contain the whole
|
||||||
palette from [simple commands](/syntax/basicgrammar#simple_commands)
|
palette from [simple commands](../../syntax/basicgrammar.md#simple_commands)
|
||||||
over [pipelines](/syntax/basicgrammar#pipelines) to [compound
|
over [pipelines](../../syntax/basicgrammar.md#pipelines) to [compound
|
||||||
commands](/syntax/basicgrammar#compound_commands) (and their
|
commands](../../syntax/basicgrammar.md#compound_commands) (and their
|
||||||
combination) as condition.
|
combination) as condition.
|
||||||
|
|
||||||
### Operation
|
### Operation
|
||||||
@ -88,4 +88,4 @@ example above (multiple commands):
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [the classic test command](/commands/classictest)
|
- Internal: [the classic test command](../../commands/classictest.md)
|
||||||
|
@ -2,34 +2,34 @@
|
|||||||
|
|
||||||
The main part of Bash\'s syntax are the so-called **compound commands**.
|
The main part of Bash\'s syntax are the so-called **compound commands**.
|
||||||
They\'re called like that because they use \"real\" commands ([simple
|
They\'re called like that because they use \"real\" commands ([simple
|
||||||
commands](/syntax/basicgrammar#simple_commands) or
|
commands](../../syntax/basicgrammar.md#simple_commands) or
|
||||||
[lists](/syntax/basicgrammar#lists)) and knit some intelligence around
|
[lists](../../syntax/basicgrammar.md#lists)) and knit some intelligence around
|
||||||
them. That is what the essential \"Bash language\" is made of.
|
them. That is what the essential \"Bash language\" is made of.
|
||||||
|
|
||||||
## Command grouping
|
## Command grouping
|
||||||
|
|
||||||
- grouping: [command grouping](grouping_plain)
|
- grouping: [command grouping](../../grouping_plain.md)
|
||||||
- grouping again: [command grouping in a subshell](grouping_subshell)
|
- grouping again: [command grouping in a subshell](../../grouping_subshell.md)
|
||||||
|
|
||||||
## Conditional reactions
|
## Conditional reactions
|
||||||
|
|
||||||
Note that conditionals can also be scripted using
|
Note that conditionals can also be scripted using
|
||||||
[list](/syntax/basicgrammar#lists), which are syntax elements, not
|
[list](../../syntax/basicgrammar.md#lists), which are syntax elements, not
|
||||||
commands.
|
commands.
|
||||||
|
|
||||||
- the \"new\" test command: [conditional
|
- the \"new\" test command: [conditional
|
||||||
expression](conditional_expression)
|
expression](../../conditional_expression.md)
|
||||||
- if-clause: [conditional branching](if_clause)
|
- if-clause: [conditional branching](../../if_clause.md)
|
||||||
- case statement: [pattern-based branching](case)
|
- case statement: [pattern-based branching](../../case.md)
|
||||||
|
|
||||||
## Loops
|
## Loops
|
||||||
|
|
||||||
- [classic for-loop](classic_for)
|
- [classic for-loop](../../classic_for.md)
|
||||||
- [C-style for-loop](c_for)
|
- [C-style for-loop](../../c_for.md)
|
||||||
- [while loop](while_loop)
|
- [while loop](../../while_loop.md)
|
||||||
- [until loop](until_loop)
|
- [until loop](../../until_loop.md)
|
||||||
|
|
||||||
## Misc
|
## Misc
|
||||||
|
|
||||||
- math: [arithmetic evaluation](arithmetic_eval)
|
- math: [arithmetic evaluation](../../arithmetic_eval.md)
|
||||||
- menus: [user selections](user_select)
|
- menus: [user selections](../../user_select.md)
|
||||||
|
@ -9,12 +9,12 @@
|
|||||||
## Description
|
## Description
|
||||||
|
|
||||||
The until-loop is relatively simple in what it does: it executes the
|
The until-loop is relatively simple in what it does: it executes the
|
||||||
[command list](/syntax/basicgrammar#lists) `<LIST1>` and if the exit
|
[command list](../../syntax/basicgrammar.md#lists) `<LIST1>` and if the exit
|
||||||
code of it was **not** 0 (FALSE) it executes `<LIST2>`. This happens
|
code of it was **not** 0 (FALSE) it executes `<LIST2>`. This happens
|
||||||
again and again until `<LIST1>` returns TRUE.
|
again and again until `<LIST1>` returns TRUE.
|
||||||
|
|
||||||
This is exactly the opposite of the [while
|
This is exactly the opposite of the [while
|
||||||
loop](/syntax/ccmd/while_loop).
|
loop](../../syntax/ccmd/while_loop.md).
|
||||||
|
|
||||||
:!: Like all loops (both `for`-loops, `while` and `until`), this loop
|
:!: Like all loops (both `for`-loops, `while` and `until`), this loop
|
||||||
can be
|
can be
|
||||||
@ -35,4 +35,4 @@ or `0` (`TRUE`) if none was executed.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [The while loop](/syntax/ccmd/while_loop)
|
- Internal: [The while loop](../../syntax/ccmd/while_loop.md)
|
||||||
|
@ -27,7 +27,7 @@
|
|||||||
This compound command provides a kind of menu. The user is prompted with
|
This compound command provides a kind of menu. The user is prompted with
|
||||||
a *numbered list* of the given words, and is asked to input the index
|
a *numbered list* of the given words, and is asked to input the index
|
||||||
number of the word. If a word was selected, the variable `<NAME>` is set
|
number of the word. If a word was selected, the variable `<NAME>` is set
|
||||||
to this word, and the [list](/syntax/basicgrammar#lists) `<LIST>` is
|
to this word, and the [list](../../syntax/basicgrammar.md#lists) `<LIST>` is
|
||||||
executed.
|
executed.
|
||||||
|
|
||||||
If no `in <WORDS>` is given, then the positional parameters are taken as
|
If no `in <WORDS>` is given, then the positional parameters are taken as
|
||||||
|
@ -9,12 +9,12 @@
|
|||||||
## Description
|
## Description
|
||||||
|
|
||||||
The while-loop is relatively simple in what it does: it executes the
|
The while-loop is relatively simple in what it does: it executes the
|
||||||
[command list](/syntax/basicgrammar#lists) `<LIST1>` and if the exit
|
[command list](../../syntax/basicgrammar.md#lists) `<LIST1>` and if the exit
|
||||||
code of it was 0 (TRUE) it executes `<LIST2>`. This happens again and
|
code of it was 0 (TRUE) it executes `<LIST2>`. This happens again and
|
||||||
again until `<LIST1>` returns FALSE.
|
again until `<LIST1>` returns FALSE.
|
||||||
|
|
||||||
This is exactly the opposite of the [until
|
This is exactly the opposite of the [until
|
||||||
loop](/syntax/ccmd/until_loop).
|
loop](../../syntax/ccmd/until_loop.md).
|
||||||
|
|
||||||
:!: Like all loops (both `for`-loops, `while` and `until`), this loop
|
:!: Like all loops (both `for`-loops, `while` and `until`), this loop
|
||||||
can be
|
can be
|
||||||
@ -35,7 +35,7 @@ or `0` (`TRUE`) if none was executed.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [The until loop](/syntax/ccmd/until_loop)
|
- Internal: [The until loop](../../syntax/ccmd/until_loop.md)
|
||||||
- Internal: [code examples of the read builtin
|
- Internal: [code examples of the read builtin
|
||||||
command](/commands/builtin/read#code_examples) to see how you can
|
command](../../commands/builtin/read.md#code_examples) to see how you can
|
||||||
loop over lines
|
loop over lines
|
||||||
|
@ -4,7 +4,7 @@
|
|||||||
|
|
||||||
$[ <EXPRESSION> ]
|
$[ <EXPRESSION> ]
|
||||||
|
|
||||||
The [arithmetic expression](/syntax/arith_expr) `<EXPRESSION>` is
|
The [arithmetic expression](../../syntax/arith_expr.md) `<EXPRESSION>` is
|
||||||
evaluated and expands to the result. The output of the arithmetic
|
evaluated and expands to the result. The output of the arithmetic
|
||||||
expansion is guaranteed to be one word and a digit in Bash.
|
expansion is guaranteed to be one word and a digit in Bash.
|
||||||
|
|
||||||
@ -29,7 +29,7 @@ function printSum {
|
|||||||
**Note** that in Bash you don\'t need the arithmetic expansion to check
|
**Note** that in Bash you don\'t need the arithmetic expansion to check
|
||||||
for the boolean value of an arithmetic expression. This can be done
|
for the boolean value of an arithmetic expression. This can be done
|
||||||
using the [arithmetic evaluation compound
|
using the [arithmetic evaluation compound
|
||||||
command](/syntax/ccmd/arithmetic_eval):
|
command](../../syntax/ccmd/arithmetic_eval.md):
|
||||||
|
|
||||||
``` bash
|
``` bash
|
||||||
printf %s 'Enter a number: ' >&2
|
printf %s 'Enter a number: ' >&2
|
||||||
@ -66,10 +66,10 @@ echo $(($x[0])) # Error. This expands to $((1[0])), an invalid expression.
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [arithmetic expressions](/syntax/arith_expr)
|
- [arithmetic expressions](../../syntax/arith_expr.md)
|
||||||
- [arithmetic evaluation compound
|
- [arithmetic evaluation compound
|
||||||
command](/syntax/ccmd/arithmetic_eval)
|
command](../../syntax/ccmd/arithmetic_eval.md)
|
||||||
- [Introduction to expansion and
|
- [Introduction to expansion and
|
||||||
substitution](/syntax/expansion/intro)
|
substitution](../../syntax/expansion/intro.md)
|
||||||
- [POSIX
|
- [POSIX
|
||||||
definition](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_04)
|
definition](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_04)
|
||||||
|
@ -40,7 +40,7 @@ instance, when embedded inside a for loop :
|
|||||||
`for i in $(eval echo {$a..$b})` This requires that the entire command
|
`for i in $(eval echo {$a..$b})` This requires that the entire command
|
||||||
be properly escaped to avoid unexpected expansions. If the sequence
|
be properly escaped to avoid unexpected expansions. If the sequence
|
||||||
expansion is to be assigned to an array, another method is possible
|
expansion is to be assigned to an array, another method is possible
|
||||||
using [declaration commands](/commands/builtin/declare):
|
using [declaration commands](../../commands/builtin/declare.md):
|
||||||
`declare -a 'pics=(img{'"$a..$b"'}.png)'; mv "${pics[@]}" ../imgs` This
|
`declare -a 'pics=(img{'"$a..$b"'}.png)'; mv "${pics[@]}" ../imgs` This
|
||||||
is significantly safer, but one must still be careful to control the
|
is significantly safer, but one must still be careful to control the
|
||||||
values of \$a and \$b. Both the exact quoting, and explicitly including
|
values of \$a and \$b. Both the exact quoting, and explicitly including
|
||||||
@ -269,4 +269,4 @@ letter-ranges:
|
|||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [Introduction to expansion and
|
- [Introduction to expansion and
|
||||||
substitution](/syntax/expansion/intro)
|
substitution](../../syntax/expansion/intro.md)
|
||||||
|
@ -14,8 +14,8 @@ All **trailing** newlines are removed (below is an example for a
|
|||||||
workaround).
|
workaround).
|
||||||
|
|
||||||
In later steps, **if not quoted**, the results undergo [word
|
In later steps, **if not quoted**, the results undergo [word
|
||||||
splitting](/syntax/expansion/wordsplit) and [pathname
|
splitting](../../syntax/expansion/wordsplit.md) and [pathname
|
||||||
expansion](/syntax/expansion/globs). You have to remember that, because
|
expansion](../../syntax/expansion/globs.md). You have to remember that, because
|
||||||
the word splitting will also remove embedded newlines and other `IFS`
|
the word splitting will also remove embedded newlines and other `IFS`
|
||||||
characters and break the results up into several words. Also you\'ll
|
characters and break the results up into several words. Also you\'ll
|
||||||
probably get unexpected pathname matches. **If you need the literal
|
probably get unexpected pathname matches. **If you need the literal
|
||||||
@ -25,14 +25,14 @@ The second form `` `COMMAND` `` is more or less obsolete for Bash, since
|
|||||||
it has some trouble with nesting (\"inner\" backticks need to be
|
it has some trouble with nesting (\"inner\" backticks need to be
|
||||||
escaped) and escaping characters. Use `$(COMMAND)`, it\'s also POSIX!
|
escaped) and escaping characters. Use `$(COMMAND)`, it\'s also POSIX!
|
||||||
|
|
||||||
When you [call an explicit subshell](/syntax/ccmd/grouping_subshell)
|
When you [call an explicit subshell](../../syntax/ccmd/grouping_subshell.md)
|
||||||
`(COMMAND)` inside the command substitution `$()`, then take care, this
|
`(COMMAND)` inside the command substitution `$()`, then take care, this
|
||||||
way is **wrong**:
|
way is **wrong**:
|
||||||
|
|
||||||
$((COMMAND))
|
$((COMMAND))
|
||||||
|
|
||||||
Why? because it collides with the syntax for [arithmetic
|
Why? because it collides with the syntax for [arithmetic
|
||||||
expansion](/syntax/expansion/arith). You need to separate the command
|
expansion](../../syntax/expansion/arith.md). You need to separate the command
|
||||||
substitution from the inner `(COMMAND)`:
|
substitution from the inner `(COMMAND)`:
|
||||||
|
|
||||||
$( (COMMAND) )
|
$( (COMMAND) )
|
||||||
@ -134,5 +134,5 @@ commands\' output with its trailing newlines.
|
|||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [Introduction to expansion and
|
- Internal: [Introduction to expansion and
|
||||||
substitution](/syntax/expansion/intro)
|
substitution](../../syntax/expansion/intro.md)
|
||||||
- Internal: [Obsolete and deprecated syntax](/scripting/obsolete)
|
- Internal: [Obsolete and deprecated syntax](../../scripting/obsolete.md)
|
||||||
|
@ -11,16 +11,16 @@ matching `*.log`):
|
|||||||
grep "changes:" *.log
|
grep "changes:" *.log
|
||||||
|
|
||||||
The base syntax for the pathname expansion is the [pattern
|
The base syntax for the pathname expansion is the [pattern
|
||||||
matching](/syntax/pattern) syntax. The pattern you describe is matched
|
matching](../../syntax/pattern.md) syntax. The pattern you describe is matched
|
||||||
against all existing filenames and the matching ones are substituted.
|
against all existing filenames and the matching ones are substituted.
|
||||||
Since this substitution happens **after [word
|
Since this substitution happens **after [word
|
||||||
splitting](/syntax/expansion/wordsplit)**, all resulting filenames are
|
splitting](../../syntax/expansion/wordsplit.md)**, all resulting filenames are
|
||||||
literal and treated as separate words, no matter how many spaces or
|
literal and treated as separate words, no matter how many spaces or
|
||||||
other `IFS`-characters they contain.
|
other `IFS`-characters they contain.
|
||||||
|
|
||||||
## Normal behaviour
|
## Normal behaviour
|
||||||
|
|
||||||
- with [the set command](/commands/builtin/set) (`-f`, `noglob`) you
|
- with [the set command](../../commands/builtin/set.md) (`-f`, `noglob`) you
|
||||||
can entirely disable pathname expansion
|
can entirely disable pathname expansion
|
||||||
- when matching a pathname, the slash-character (`/`) always needs to
|
- when matching a pathname, the slash-character (`/`) always needs to
|
||||||
be matched explicitly
|
be matched explicitly
|
||||||
@ -49,7 +49,7 @@ other `IFS`-characters they contain.
|
|||||||
globs (e.g. `[A-Z]`) use C locale order rather than the configured
|
globs (e.g. `[A-Z]`) use C locale order rather than the configured
|
||||||
locale\'s order (i.e. `ABC...abc...` instead of e.g. `AaBbCc...`) -
|
locale\'s order (i.e. `ABC...abc...` instead of e.g. `AaBbCc...`) -
|
||||||
since 4.3-alpha
|
since 4.3-alpha
|
||||||
- the variable [GLOBIGNORE](/syntax/shellvars#GLOBIGNORE) can be set
|
- the variable [GLOBIGNORE](../../syntax/shellvars.md#GLOBIGNORE) can be set
|
||||||
to a colon-separated list of patterns to be removed from the list
|
to a colon-separated list of patterns to be removed from the list
|
||||||
before it is returned
|
before it is returned
|
||||||
|
|
||||||
@ -66,7 +66,7 @@ In this example, no files matched the pattern, so the glob was left
|
|||||||
intact (a literal asterisk, followed by dot-txt).
|
intact (a literal asterisk, followed by dot-txt).
|
||||||
|
|
||||||
This can be very annoying, for example when you drive a
|
This can be very annoying, for example when you drive a
|
||||||
[for-loop](/syntax/ccmd/classic_for) using the pathname expansion:
|
[for-loop](../../syntax/ccmd/classic_for.md) using the pathname expansion:
|
||||||
|
|
||||||
for filename in *.txt; do
|
for filename in *.txt; do
|
||||||
echo "=== BEGIN: $filename ==="
|
echo "=== BEGIN: $filename ==="
|
||||||
@ -107,8 +107,8 @@ followed by two numbers, followed by at least 3 more characters:
|
|||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [Introduction to expansion and
|
- [Introduction to expansion and
|
||||||
substitution](/syntax/expansion/intro)
|
substitution](../../syntax/expansion/intro.md)
|
||||||
- [pattern matching syntax](/syntax/pattern)
|
- [pattern matching syntax](../../syntax/pattern.md)
|
||||||
- [the set builtin command](/commands/builtin/set)
|
- [the set builtin command](../../commands/builtin/set.md)
|
||||||
- [the shopt builtin command](/commands/builtin/shopt)
|
- [the shopt builtin command](../../commands/builtin/shopt.md)
|
||||||
- [list of shell options](/internals/shell_options)
|
- [list of shell options](../../internals/shell_options.md)
|
||||||
|
@ -21,7 +21,7 @@ see `Hello world`, not the variable or anything else!
|
|||||||
|
|
||||||
After all these expansions and substitutions are done, all quotes that
|
After all these expansions and substitutions are done, all quotes that
|
||||||
are not meant literally (i.e., [the quotes that marked contiguous
|
are not meant literally (i.e., [the quotes that marked contiguous
|
||||||
words](/syntax/quoting), as part of the shell syntax) are removed from
|
words](../../syntax/quoting.md), as part of the shell syntax) are removed from
|
||||||
the commandline text, so the called program won\'t see them. This step
|
the commandline text, so the called program won\'t see them. This step
|
||||||
is called **quote-removal**.
|
is called **quote-removal**.
|
||||||
|
|
||||||
@ -30,28 +30,28 @@ is called **quote-removal**.
|
|||||||
Saw a possible expansion syntax but don\'t know what it is? Here\'s a
|
Saw a possible expansion syntax but don\'t know what it is? Here\'s a
|
||||||
small list.
|
small list.
|
||||||
|
|
||||||
- [Parameter expansion](/syntax/pe) (it has its own [overview
|
- [Parameter expansion](../../syntax/pe.md) (it has its own [overview
|
||||||
section](/syntax/pe#overview))
|
section](../../syntax/pe.md#overview))
|
||||||
- `$WORD`
|
- `$WORD`
|
||||||
- `${STUFF...}`
|
- `${STUFF...}`
|
||||||
- [Pathname expansion](/syntax/expansion/globs)
|
- [Pathname expansion](../../syntax/expansion/globs.md)
|
||||||
- `*.txt`
|
- `*.txt`
|
||||||
- `page_1?.html`
|
- `page_1?.html`
|
||||||
- [Arithmetic expansion](/syntax/expansion/arith)
|
- [Arithmetic expansion](../../syntax/expansion/arith.md)
|
||||||
- `$(( EXPRESSION ))`
|
- `$(( EXPRESSION ))`
|
||||||
- `$[ EXPRESSION ]`
|
- `$[ EXPRESSION ]`
|
||||||
- [Command substitution](/syntax/expansion/cmdsubst)
|
- [Command substitution](../../syntax/expansion/cmdsubst.md)
|
||||||
- `$( COMMAND )`
|
- `$( COMMAND )`
|
||||||
- `` ` COMMAND ` ``
|
- `` ` COMMAND ` ``
|
||||||
- [Tilde expansion](/syntax/expansion/tilde)
|
- [Tilde expansion](../../syntax/expansion/tilde.md)
|
||||||
- `~`
|
- `~`
|
||||||
- `~+`
|
- `~+`
|
||||||
- `~-`
|
- `~-`
|
||||||
- [Brace expansion](/syntax/expansion/brace)
|
- [Brace expansion](../../syntax/expansion/brace.md)
|
||||||
- `{X,Y,Z}`
|
- `{X,Y,Z}`
|
||||||
- `{X..Y}`
|
- `{X..Y}`
|
||||||
- `{X..Y..Z}`
|
- `{X..Y..Z}`
|
||||||
- [Process substitution](/syntax/expansion/proc_subst)
|
- [Process substitution](../../syntax/expansion/proc_subst.md)
|
||||||
- `<( COMMAND )`
|
- `<( COMMAND )`
|
||||||
- `>( COMMAND )`
|
- `>( COMMAND )`
|
||||||
|
|
||||||
@ -64,25 +64,25 @@ splitting!).
|
|||||||
|
|
||||||
The order is (from first to last):
|
The order is (from first to last):
|
||||||
|
|
||||||
- [Brace expansion](/syntax/expansion/brace)
|
- [Brace expansion](../../syntax/expansion/brace.md)
|
||||||
- [Tilde expansion](/syntax/expansion/tilde)
|
- [Tilde expansion](../../syntax/expansion/tilde.md)
|
||||||
- The following expansions happen at the same time, in a left-to-right
|
- The following expansions happen at the same time, in a left-to-right
|
||||||
fashion on the commandline (see below)
|
fashion on the commandline (see below)
|
||||||
- [Parameter expansion](/syntax/pe)
|
- [Parameter expansion](../../syntax/pe.md)
|
||||||
- [Arithmetic expansion](/syntax/expansion/arith)
|
- [Arithmetic expansion](../../syntax/expansion/arith.md)
|
||||||
- [Command substitution](/syntax/expansion/cmdsubst)
|
- [Command substitution](../../syntax/expansion/cmdsubst.md)
|
||||||
- [Word splitting](/syntax/expansion/wordsplit)
|
- [Word splitting](../../syntax/expansion/wordsplit.md)
|
||||||
- [Pathname expansion](/syntax/expansion/globs)
|
- [Pathname expansion](../../syntax/expansion/globs.md)
|
||||||
|
|
||||||
[Process substitution](/syntax/expansion/proc_subst) is performed
|
[Process substitution](../../syntax/expansion/proc_subst.md) is performed
|
||||||
**simultaneously** with [parameter expansion](/syntax/pe), [command
|
**simultaneously** with [parameter expansion](../../syntax/pe.md), [command
|
||||||
substitution](/syntax/expansion/cmdsubst) and [arithmetic
|
substitution](../../syntax/expansion/cmdsubst.md) and [arithmetic
|
||||||
expansion](/syntax/expansion/arith). It is only performed when the
|
expansion](../../syntax/expansion/arith.md). It is only performed when the
|
||||||
underlying operating system supports it.
|
underlying operating system supports it.
|
||||||
|
|
||||||
The 3 steps [parameter expansion](/syntax/pe), [arithmetic
|
The 3 steps [parameter expansion](../../syntax/pe.md), [arithmetic
|
||||||
expansion](/syntax/expansion/arith) and [command
|
expansion](../../syntax/expansion/arith.md) and [command
|
||||||
substitution](/syntax/expansion/cmdsubst) happen at the same time in a
|
substitution](../../syntax/expansion/cmdsubst.md) happen at the same time in a
|
||||||
left-to-right fashion on nthe commandline. This means
|
left-to-right fashion on nthe commandline. This means
|
||||||
|
|
||||||
i=1
|
i=1
|
||||||
|
@ -10,11 +10,11 @@ of a process (some sequence of commands) appear as a temporary file.
|
|||||||
>( <LIST> )
|
>( <LIST> )
|
||||||
|
|
||||||
Process substitution is performed **simultaneously** with [parameter
|
Process substitution is performed **simultaneously** with [parameter
|
||||||
expansion](/syntax/pe), [command
|
expansion](../../syntax/pe.md), [command
|
||||||
substitution](/syntax/expansion/cmdsubst) and [arithmetic
|
substitution](../../syntax/expansion/cmdsubst.md) and [arithmetic
|
||||||
expansion](/syntax/expansion/arith).
|
expansion](../../syntax/expansion/arith.md).
|
||||||
|
|
||||||
The [command list](/syntax/basicgrammar#lists) `<LIST>` is executed and
|
The [command list](../../syntax/basicgrammar.md#lists) `<LIST>` is executed and
|
||||||
its
|
its
|
||||||
|
|
||||||
- standard output filedescriptor in the `<( ... )` form or
|
- standard output filedescriptor in the `<( ... )` form or
|
||||||
@ -126,7 +126,7 @@ echo "$counter files"
|
|||||||
This is the normal input file redirection `< FILE`, just that the `FILE`
|
This is the normal input file redirection `< FILE`, just that the `FILE`
|
||||||
in this case is the result of process substitution. It\'s important to
|
in this case is the result of process substitution. It\'s important to
|
||||||
note that the space is required in order to disambiguate the syntax from
|
note that the space is required in order to disambiguate the syntax from
|
||||||
[here documents](/syntax/redirection#here_documents).
|
[here documents](../../syntax/redirection.md#here_documents).
|
||||||
|
|
||||||
``` bash
|
``` bash
|
||||||
: < <(COMMAND) # Good.
|
: < <(COMMAND) # Good.
|
||||||
@ -158,7 +158,7 @@ See the above section on [#scope](#scope)
|
|||||||
not (yet) pdksh derivatives (mksh). Coprocesses may be used instead.
|
not (yet) pdksh derivatives (mksh). Coprocesses may be used instead.
|
||||||
- Process substitution is supported only on systems that support
|
- Process substitution is supported only on systems that support
|
||||||
either named pipes (FIFO - a [special
|
either named pipes (FIFO - a [special
|
||||||
file](/dict/terms/special_file)) or the `/dev/fd/*` method for
|
file](../../dict/terms/special_file.md)) or the `/dev/fd/*` method for
|
||||||
accessing open files. If the system doesn\'t support `/dev/fd/*`,
|
accessing open files. If the system doesn\'t support `/dev/fd/*`,
|
||||||
Bash falls back to creating named pipes. Note that not all shells
|
Bash falls back to creating named pipes. Note that not all shells
|
||||||
that support process substitution have that fallback.
|
that support process substitution have that fallback.
|
||||||
@ -178,7 +178,7 @@ ${dev[${dev='dev[1>(${dev[dev]})]'}]}
|
|||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [Introduction to expansion and
|
- Internal: [Introduction to expansion and
|
||||||
substitution](/syntax/expansion/intro)
|
substitution](../../syntax/expansion/intro.md)
|
||||||
- Internal: [Bash in the process tree](/scripting/processtree)
|
- Internal: [Bash in the process tree](../../scripting/processtree.md)
|
||||||
(subshells)
|
(subshells)
|
||||||
- Internal: [Redirection](/syntax/redirection)
|
- Internal: [Redirection](../../syntax/redirection.md)
|
||||||
|
@ -42,7 +42,7 @@ Tilde expansion is also performed everytime a variable is assigned:
|
|||||||
I don\'t know yet, if this is a bug or intended. \</note\>
|
I don\'t know yet, if this is a bug or intended. \</note\>
|
||||||
|
|
||||||
This way you can correctly use the tilde expansion in your
|
This way you can correctly use the tilde expansion in your
|
||||||
[PATH](/syntax/shellvars#PATH):
|
[PATH](../../syntax/shellvars.md#PATH):
|
||||||
|
|
||||||
PATH=~/mybins:~peter/mybins:$PATH
|
PATH=~/mybins:~peter/mybins:$PATH
|
||||||
|
|
||||||
@ -68,7 +68,7 @@ operating system for the associated home directory for `<NAME>`.
|
|||||||
To find the home directory of the current user (`~`), Bash has a
|
To find the home directory of the current user (`~`), Bash has a
|
||||||
precedence:
|
precedence:
|
||||||
|
|
||||||
- expand to the value of [HOME](/syntax/shellvars#HOME) if it\'s
|
- expand to the value of [HOME](../../syntax/shellvars.md#HOME) if it\'s
|
||||||
defined
|
defined
|
||||||
- expand to the home directory of the user executing the shell
|
- expand to the home directory of the user executing the shell
|
||||||
(operating system)
|
(operating system)
|
||||||
@ -80,7 +80,7 @@ directory, at least regarding tilde expansion.
|
|||||||
|
|
||||||
~+
|
~+
|
||||||
|
|
||||||
This expands to the value of the [PWD](/syntax/shellvars#PWD) variable,
|
This expands to the value of the [PWD](../../syntax/shellvars.md#PWD) variable,
|
||||||
which holds the currect working directory:
|
which holds the currect working directory:
|
||||||
|
|
||||||
echo "CWD is $PWD"
|
echo "CWD is $PWD"
|
||||||
@ -93,7 +93,7 @@ is equivalent to (note it **must** be a separate word!):
|
|||||||
|
|
||||||
~-
|
~-
|
||||||
|
|
||||||
This expands to the value of the [OLDPWD](/syntax/shellvars#OLDPWD)
|
This expands to the value of the [OLDPWD](../../syntax/shellvars.md#OLDPWD)
|
||||||
variable, which holds the previous working directory (the one before the
|
variable, which holds the previous working directory (the one before the
|
||||||
last `cd`). If `OLDPWD` is unset (never changed the directory), it is
|
last `cd`). If `OLDPWD` is unset (never changed the directory), it is
|
||||||
not expanded.
|
not expanded.
|
||||||
@ -107,4 +107,4 @@ not expanded.
|
|||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [Introduction to expansion and
|
- Internal: [Introduction to expansion and
|
||||||
substitution](/syntax/expansion/intro)
|
substitution](../../syntax/expansion/intro.md)
|
||||||
|
@ -5,9 +5,9 @@ FIXME to be continued!
|
|||||||
Word splitting occurs once any of the following expansions are done (and
|
Word splitting occurs once any of the following expansions are done (and
|
||||||
only then!)
|
only then!)
|
||||||
|
|
||||||
- [Parameter expansion](/syntax/pe)
|
- [Parameter expansion](../../syntax/pe.md)
|
||||||
- [Command substitution](/syntax/expansion/cmdsubst)
|
- [Command substitution](../../syntax/expansion/cmdsubst.md)
|
||||||
- [Arithmetic expansion](/syntax/expansion/arith)
|
- [Arithmetic expansion](../../syntax/expansion/arith.md)
|
||||||
|
|
||||||
Bash will scan the results of these expansions for special `IFS`
|
Bash will scan the results of these expansions for special `IFS`
|
||||||
characters that mark word boundaries. This is only done on results that
|
characters that mark word boundaries. This is only done on results that
|
||||||
@ -44,8 +44,8 @@ is solely responsible.
|
|||||||
## See also
|
## See also
|
||||||
|
|
||||||
- [Introduction to expansion and
|
- [Introduction to expansion and
|
||||||
substitution](/syntax/expansion/intro)
|
substitution](../../syntax/expansion/intro.md)
|
||||||
- [Quoting and escaping](/syntax/quoting)
|
- [Quoting and escaping](../../syntax/quoting.md)
|
||||||
- [WordSplitting](http://mywiki.wooledge.org/WordSplitting),
|
- [WordSplitting](http://mywiki.wooledge.org/WordSplitting),
|
||||||
[IFS](http://mywiki.wooledge.org/IFS), and
|
[IFS](http://mywiki.wooledge.org/IFS), and
|
||||||
[DontReadLinesWithFor](http://mywiki.wooledge.org/DontReadLinesWithFor) -
|
[DontReadLinesWithFor](http://mywiki.wooledge.org/DontReadLinesWithFor) -
|
||||||
|
@ -4,7 +4,7 @@ FIXME work in progress\...
|
|||||||
|
|
||||||
![](keywords>bash shell scripting syntax language behaviour executing execution)
|
![](keywords>bash shell scripting syntax language behaviour executing execution)
|
||||||
|
|
||||||
Nearly everything in [Bash grammar](/syntax/basicgrammar) can be broken
|
Nearly everything in [Bash grammar](../../syntax/basicgrammar.md) can be broken
|
||||||
down to a \"simple command\". The only thing Bash has to expand,
|
down to a \"simple command\". The only thing Bash has to expand,
|
||||||
evaluate and execute is the simple command.
|
evaluate and execute is the simple command.
|
||||||
|
|
||||||
@ -27,16 +27,16 @@ the simple command **from left to right**):
|
|||||||
- variable assignments precede the command name and have the form
|
- variable assignments precede the command name and have the form
|
||||||
`WORD=WORD`
|
`WORD=WORD`
|
||||||
- redirections can appear anywhere in the simple command
|
- redirections can appear anywhere in the simple command
|
||||||
2. The rest of the words are [expanded](/syntax/expansion/intro). If
|
2. The rest of the words are [expanded](../../syntax/expansion/intro.md). If
|
||||||
any words remain after expansion, the first word is taken to be the
|
any words remain after expansion, the first word is taken to be the
|
||||||
**name of the command** and the remaining words are the
|
**name of the command** and the remaining words are the
|
||||||
**arguments**.
|
**arguments**.
|
||||||
3. [Redirections](/syntax/redirection) are performed.
|
3. [Redirections](../../syntax/redirection.md) are performed.
|
||||||
4. The text after the `=` in each variable assignment undergoes [tilde
|
4. The text after the `=` in each variable assignment undergoes [tilde
|
||||||
expansion](/syntax/expansion/tilde), [parameter
|
expansion](../../syntax/expansion/tilde.md), [parameter
|
||||||
expansion](/syntax/pe), [command
|
expansion](../../syntax/pe.md), [command
|
||||||
substitution](/syntax/expansion/cmdsubst), [arithmetic
|
substitution](../../syntax/expansion/cmdsubst.md), [arithmetic
|
||||||
expansion](/syntax/expansion/arith), and quote removal before being
|
expansion](../../syntax/expansion/arith.md), and quote removal before being
|
||||||
assigned to the variable.
|
assigned to the variable.
|
||||||
|
|
||||||
If **no command name** results after expansion:
|
If **no command name** results after expansion:
|
||||||
@ -120,6 +120,6 @@ FIXME to be continued
|
|||||||
|
|
||||||
## See also
|
## See also
|
||||||
|
|
||||||
- Internal: [Redirection](/syntax/redirection)
|
- Internal: [Redirection](../../syntax/redirection.md)
|
||||||
- Internal: [Introduction to expansions and
|
- Internal: [Introduction to expansions and
|
||||||
substitutions](/syntax/expansion/intro)
|
substitutions](../../syntax/expansion/intro.md)
|
||||||
|
@ -18,7 +18,7 @@ The process ID of the shell spawned to execute the coprocess is
|
|||||||
available through the value of the variable named by `NAME` followed by
|
available through the value of the variable named by `NAME` followed by
|
||||||
a `_PID` suffix. For example, the variable name used to store the PID of
|
a `_PID` suffix. For example, the variable name used to store the PID of
|
||||||
a coproc started with no `NAME` given would be `COPROC_PID` (because
|
a coproc started with no `NAME` given would be `COPROC_PID` (because
|
||||||
`COPROC` is the default `NAME`). [wait](/commands/builtin/wait) may be
|
`COPROC` is the default `NAME`). [wait](../../commands/builtin/wait.md) may be
|
||||||
used to wait for the coprocess to terminate. Additionally, coprocesses
|
used to wait for the coprocess to terminate. Additionally, coprocesses
|
||||||
may be manipulated through their `jobspec`.
|
may be manipulated through their `jobspec`.
|
||||||
|
|
||||||
|
Loading…
Reference in New Issue
Block a user