When I'm using a POSIX compliant shell (es: dash, bash, zsh, ...) can I be sure that * will always expand in alphabetical order (dictated by LC_COLLATE)?
example:
$ echo 1 > file_a $ echo 2 > file_b $ echo 3 > file_c $ cat * 1 2 3 
- See also What is the sort order when using conditional operators?, which has a little more detail.Adam Katz– Adam Katz2021-10-10 19:31:23 +00:00Commented Oct 10, 2021 at 19:31
- 1Does this answer your question? What is the sort order when using conditional operators?Adam Katz– Adam Katz2021-10-10 19:32:39 +00:00Commented Oct 10, 2021 at 19:32
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2 Answers
That behavior is required by POSIX, and you're safe to rely on it.
Another note that you want to set your locale to C to get consistent behavior. In locale with collation elements have the same sorting order, you will have strange result.
On GNU system with UTF-8 locale:
$ printf '%b\n' '\U2461' '\U2460' | sort ② ① or:
$ printf '%s\n' A B a b | sort a A b B Setting to C locale:
$ printf '%b\n' '\U2461' '\U2460' | LC_ALL=C sort ① ② $ printf '%s\n' A B a b | LC_ALL=C sort A B a b Some shells even do not support multibyte characters like dash, mksh or support but will choke on invalid sequences of bytes like yash.
- Another reason to stick to
LC_COLLATE=Cis that some shells don't support multibyte characters in pattern matching (e.g. dash, mksh).Gilles 'SO- stop being evil'– Gilles 'SO- stop being evil'2015-11-18 22:26:21 +00:00Commented Nov 18, 2015 at 22:26 - @Gilles: Ah, right, it's fair enough. I added it to my answer, thanks.cuonglm– cuonglm2015-11-19 01:34:32 +00:00Commented Nov 19, 2015 at 1:34
Yes. The normative answer can be found here:
If the pattern matches any existing filenames or pathnames, the pattern shall be replaced with those filenames and pathnames, sorted according to the collating sequence in effect in the current locale.
