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bash prompt: use bash builtins to find out current branch
__git_ps1() runs the '$(git symbolic-ref HEAD)' command substitution to find out whether we are on a branch and to find out the name of that branch. This imposes the overhead of fork()ing a subshell and fork()+exec()ing a git process. Since HEAD is in most cases a single-line file and the symbolic ref format is quite simple to recognize and parse, read and parse it using only bash builtins, thereby sparing all that fork()+exec() overhead. Don't display the git prompt if reading HEAD fails, because a readable HEAD is required for a git repository. HEAD can also be a symlink symbolic ref (due to 'core.preferSymlinkRefs'), so use bash builtins for reading HEAD only when HEAD is not a symlink. Signed-off-by: SZEDER Gábor <[email protected]>
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Lines changed: 33 additions & 18 deletions

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‎contrib/completion/git-prompt.sh‎

Lines changed: 33 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -355,25 +355,40 @@ __git_ps1 ()
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r="|BISECTING"
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fi
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test -n "$b" ||
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b="$(git symbolic-ref HEAD 2>/dev/null)" || {
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detached=yes
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b="$(
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case "${GIT_PS1_DESCRIBE_STYLE-}" in
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(contains)
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git describe --contains HEAD ;;
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(branch)
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git describe --contains --all HEAD ;;
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(describe)
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git describe HEAD ;;
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(* | default)
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git describe --tags --exact-match HEAD ;;
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esac 2>/dev/null)" ||
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if [ -n "$b" ]; then
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:
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elif [ -h "$g/HEAD" ]; then
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# symlink symbolic ref
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b="$(git symbolic-ref HEAD 2>/dev/null)"
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else
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local head=""
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if ! read head 2>/dev/null <"$g/HEAD"; then
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if [ $pcmode = yes ]; then
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PS1="$ps1pc_start$ps1pc_end"
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fi
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return
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fi
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# is it a symbolic ref?
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b="${head#ref: }"
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if [ "$head" = "$b" ]; then
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detached=yes
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b="$(
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case "${GIT_PS1_DESCRIBE_STYLE-}" in
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(contains)
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git describe --contains HEAD ;;
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(branch)
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git describe --contains --all HEAD ;;
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(describe)
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git describe HEAD ;;
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(* | default)
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git describe --tags --exact-match HEAD ;;
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esac 2>/dev/null)" ||
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b="$(git rev-parse --short HEAD 2>/dev/null)..." ||
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b="unknown"
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b="($b)"
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}
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b="$(git rev-parse --short HEAD 2>/dev/null)..." ||
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b="unknown"
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b="($b)"
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fi
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fi
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fi
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if [ -n "$step" ] && [ -n "$total" ]; then

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