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Re: [RFC PATCH 18/19] bash prompt: avoid command substitution when checking for untracked files

From
Junio C Hamano <gitster@pobox.com>
Date
May 9, 2012, 20:32 UTC
Message-ID
<7vr4utqemg.fsf@alter.siamese.dyndns.org>
In-Reply-To
<1336524290-30023-19-git-send-email-szeder@ira.uka.de>
SZEDER Gábor <szeder@ira.uka.de> writes:
Show 7 quoted lines
> When enabled, the bash prompt can indicate the presence of untracked
> files with a '%' sign.  __git_ps1() checks for untracked files by running the
> '$(git ls-files --others --exclude-standard)' command substitution,
> and displays the indicator when there is no output.
>
> Avoid this command substitution by additionally passing
> '--error-unmatch *', and checking the command's return value.

This is too subtle and needs to be explained in a in-code comment. For example, it is unclear to me how this '*' pathspec and an untracked file that does not fnmatch(3) with the pattern (e.g. ".trash").

        $ rm -fr /var/tmp/x && git init /var/tmp/x && cd /var/tmp/x
	$ args='ls-files --others --exclude-standard'
	$ git $args | wc -l
        0
        $ git $args --error-unmatch -- '*' >/dev/null 2>&1 ; echo $?
        1
        $ >a
        $ git $args | wc -l
	1
        $ git $args --error-unmatch -- '*' >/dev/null 2>&1 ; echo $?
	0
	$ mv a .a
        $ git $args | wc -l
	1
        $ git $args --error-unmatch -- '*' >/dev/null 2>&1 ; echo $?
	0

The first two cases seem to be fine, but isn't the last one showing that your update is incorrect?

Show 26 quoted lines
>
> Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
> ---
>
> This seems to do the right thing, but I'm not quite sure, so I would
> appreciate a pair of expert eyeballs on it.
>
>  contrib/completion/git-completion.bash | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
> index c4feab68..5ea19018 100755
> --- a/contrib/completion/git-completion.bash
> +++ b/contrib/completion/git-completion.bash
> @@ -348,9 +348,8 @@ __git_ps1 ()
>  			fi
>  
>  			if [ -n "${GIT_PS1_SHOWUNTRACKEDFILES-}" ]; then
> -				if [ -n "$(git ls-files --others --exclude-standard)" ]; then
> -					u="%"
> -				fi
> +				git ls-files --others --exclude-standard --error-unmatch -- '*' >/dev/null 2>/dev/null &&
> +				u="%"
>  			fi
>  		fi
>  	fi
Previous: SZEDER GáborNext: SZEDER Gábor
Message 47 of 50 in “Bash prompt speedup”
  1. 00/19 Bash prompt speedupSZEDER Gábor, May 9, 2012
  2. 01/19 tests: move code to run tests under bash into a helper librarySZEDER Gábor, May 9, 2012
  3. 02/19 tests: add tests for the bash prompt functions in the completion scriptSZEDER Gábor, May 9, 2012
  4. Johannes SixtMay 9, 2012
  5. Junio C HamanoMay 9, 2012
  6. Johannes SixtMay 10, 2012
  7. Junio C HamanoMay 9, 2012
  8. SZEDER GáborMay 9, 2012
  9. 03/19 completion: use __gitdir() in _git_log()SZEDER Gábor, May 9, 2012
  10. Junio C HamanoMay 9, 2012
  11. SZEDER GáborMay 9, 2012
  12. 04/19 completion: respect $GIT_DIRSZEDER Gábor, May 9, 2012
  13. Johannes SixtMay 9, 2012
  14. Junio C HamanoMay 9, 2012
  15. 05/19 bash prompt: don't show the prompt when .git/HEAD is unreadableSZEDER Gábor, May 9, 2012
  16. Junio C HamanoMay 9, 2012
  17. SZEDER GáborMay 9, 2012
  18. 06/19 bash prompt: return early from __git_ps1() when not in a git repositorySZEDER Gábor, May 9, 2012
  19. 07/19 completion: make __gitdir() store repository path in $__git_dirSZEDER Gábor, May 9, 2012
  20. Junio C HamanoMay 9, 2012
  21. 08/19 completion: use $__git_dir instead of $(__gitdir)SZEDER Gábor, May 9, 2012
  22. Junio C HamanoMay 9, 2012
  23. SZEDER GáborMay 9, 2012
  24. Junio C HamanoMay 9, 2012
  25. SZEDER GáborMay 9, 2012
  26. 09/19 completion: platform-specific helper function to get physical pathSZEDER Gábor, May 9, 2012
  27. Johannes SixtMay 9, 2012
  28. 10/19 completion: use bash builtins to search for repositorySZEDER Gábor, May 9, 2012
  29. Junio C HamanoMay 9, 2012
  30. SZEDER GáborMay 9, 2012
  31. Junio C HamanoMay 9, 2012
  32. 11/19 bash prompt: use bash builtins to find out current branchSZEDER Gábor, May 9, 2012
  33. Junio C HamanoMay 9, 2012
  34. SZEDER GáborMay 9, 2012
  35. Junio C HamanoMay 9, 2012
  36. SZEDER GáborMay 9, 2012
  37. Junio C HamanoMay 9, 2012
  38. 12/19 bash prompt: use bash builtins to check whether inside git dirSZEDER Gábor, May 9, 2012
  39. Johannes SixtMay 9, 2012
  40. Junio C HamanoMay 9, 2012
  41. 13/19 bash prompt: check whether inside the worktree only when necessarySZEDER Gábor, May 9, 2012
  42. 14/19 bash prompt: use bash builtins to find out current branch during rebaseSZEDER Gábor, May 9, 2012
  43. 15/19 bash prompt: use bash builtins to get detached HEAD abbrev. object nameSZEDER Gábor, May 9, 2012
  44. 16/19 bash prompt: display stash and upstream state even inside the repositorySZEDER Gábor, May 9, 2012
  45. 17/19 bash prompt: use bash builtins to check stash stateSZEDER Gábor, May 9, 2012
  46. 18/19 bash prompt: avoid command substitution when checking for untracked filesSZEDER Gábor, May 9, 2012
  47. Junio C HamanoMay 9, 2012
  48. 19/19 bash prompt: alternative git prompt without command substitutionSZEDER Gábor, May 9, 2012
  49. Andrew SayersMay 9, 2012
  50. SZEDER GáborMay 9, 2012

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