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82 lines
6.8 KiB
Markdown
82 lines
6.8 KiB
Markdown
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# The set builtin command
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FIXME incomplete - text, examples, maybe extended description
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## Synopsis
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set [--abefhkmnptuvxBCHP] <-o OPTIONNAME> [-][--] <POSPARAMS>
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## Description
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`set` is primarily made to
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- set the positional parameters (see [handling positional
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parameters](/scripting/posparams)) to `<POSPARAMS>`
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- set shell attributes with short options (see below)
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- set shell attributes with long option names (see below)
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Without any options, `set` displays all shell- and environment-variables
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(only is POSIX-mode) in a re-usable format `NAME=VALUE`.
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### Attributes
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All attributes below can be switched on using `-X` and switched off
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using `+X`. This is done because of the historical meaning of the `-` to
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set flags (true for most commands on UNIX(r)).
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Flag Optionname Description
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------ ---------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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`-a` `allexport` Automatically mark new and altered variables to be exported to subsequent environments.
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`-b` `notify` Don\'t wait for the next prompt to print when showing the reports for a terminated background job (only with job control)
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`-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`, `||`, `&&`)
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`-f` `noglob` Disable [pathname expansion](/syntax/expansion/globs) (globbing)
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`-h` `hashall` Remembers the location of commands when they\'re called (hashing). Enabled by default.
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`-k` `keyword` Allows to place environment-assignments everywhere in the commandline, not only infront of the called command.
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`-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).
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`-n` `noexec` Read and parse but **do not execute commands** - useful for checking scripts for syntax errors. Ignored by interactive shells.
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`-o` Set/unset attributes with long option names, e.g. `set -o noglob`. The long option names are in the second column of this table. If no option name is given, all options are printed with their current status.
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`-p` `privileged` Turn on privileged mode.
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`-t` `onecmd` Exit after reading and executing **one** command.
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`-u` `nounset` Treat unset variables as an error when performing parameter expansion. Non-interactive shells exit on this error.
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`-v` `verbose` Print shell input lines as they are read - useful for debugging.
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`-x` `xtrace` Print commands just before execution - with all expansions and substitutions done, and words marked - useful for debugging.
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`-B` `braceexpand` The shell performs [brace expansion](/syntax/expansion/brace) This is on by default.
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`-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)
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`-E` `errtrace` `ERR`-traps are inherited by by shell functions, command substitutions, and commands executed in a subshell environment.
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`-H` `histexpand` Enable `!`-style history expansion. Defaults to `on` for interactive shells.
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`-P` `physical` Don\'t follow symlinks when changing directories - use the physical filesystem structure.
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`-T` `functrace` `DEBUG`- and `RETURN`-traps are inherited by subsequent environments, like `-E` for `ERR` trap.
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`-` \"End of options\" - all following arguments are assigned to the positional parameters, even when they begin with a dash. `-x` and `-v` options are turned off. Positional parameters are unchanged (unlike using `--`!) when no further arguments are given.
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`--` If no arguments follow, the positional parameters are unset. With arguments, the positional parameters are set, even if the strings begin with a `-` (dash) like an option.
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Long options usable with `-o` without a short equivalent
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`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.
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`history` If set, command historization is done (enabled by default on interactive shells)
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`ignoreeof` The effect is as if the shell command `IGNOREEOF=10` had been executed. See [shell variables](/syntax/shellvars).
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`nolog` **(currently ignored)**
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`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)
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`posix` When set, Bash runs in POSIX mode.
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`vi` Enables a `vi`-style command line editing interface.
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## Examples
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Tag a part of a shell script to output debugging information (`-x`):
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``` bash
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#!/bin/bash
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...
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set -x # on
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...
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set +x # off
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...
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```
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## Portability considerations
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`set` and its basic behaviour and options are specified by POSIX(r).
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However, options that influence Bash-specific things are not portable,
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naturally.
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## See also
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- Internal: [The shopt builtin command](/commands/builtin/shopt)
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