mirror of
https://github.com/flokoe/bash-hackers-wiki.git
synced 2024-11-25 15:53:41 +01:00
53 lines
1.7 KiB
Markdown
53 lines
1.7 KiB
Markdown
# Word splitting
|
|
|
|
FIXME to be continued!
|
|
|
|
Word splitting occurs once any of the following expansions are done (and
|
|
only then!)
|
|
|
|
- [Parameter expansion](/syntax/pe)
|
|
- [Command substitution](/syntax/expansion/cmdsubst)
|
|
- [Arithmetic expansion](/syntax/expansion/arith)
|
|
|
|
Bash will scan the results of these expansions for special `IFS`
|
|
characters that mark word boundaries. This is only done on results that
|
|
are **not double-quoted**!
|
|
|
|
## Internal Field Separator IFS
|
|
|
|
The `IFS` variable holds the characters that Bash sees as word
|
|
boundaries in this step. The default contains the characters
|
|
|
|
- \<space\>
|
|
- \<tab\>
|
|
- \<newline\>
|
|
|
|
These characters are also assumed when IFS is **unset**. When `IFS` is
|
|
**empty** (nullstring), no word splitting is performed at all.
|
|
|
|
## Behaviour
|
|
|
|
The results of the expansions mentioned above are scanned for
|
|
`IFS`-characters. If **one or more** (in a sequence) of them is found,
|
|
the expansion result is split at these positions into multiple words.
|
|
|
|
This doesn\'t happen when the expansion results were **double-quoted**.
|
|
|
|
When a null-string (e.g., something that before expanded to
|
|
\>\>nothing\<\<) is found, it is removed, unless it is quoted (`''` or
|
|
`""`).
|
|
|
|
[**Again note:**]{.underline} Without any expansion beforehand, Bash
|
|
won\'t perform word splitting! In this case, the initial token parsing
|
|
is solely responsible.
|
|
|
|
## See also
|
|
|
|
- [Introduction to expansion and
|
|
substitution](/syntax/expansion/intro)
|
|
- [Quoting and escaping](/syntax/quoting)
|
|
- [WordSplitting](http://mywiki.wooledge.org/WordSplitting),
|
|
[IFS](http://mywiki.wooledge.org/IFS), and
|
|
[DontReadLinesWithFor](http://mywiki.wooledge.org/DontReadLinesWithFor) -
|
|
Greg\'s wiki
|