bash prompt: use bash builtins to find out rebase state

During an ongoing interactive rebase __git_ps1() finds out the name of
the rebased branch, the total number of patches and the number of the
current patch by executing a '$(cat .git/rebase-merge/<FILE>)' command
substitution for each.  That is not quite the most efficient way to
read single line single word files, because it imposes the overhead of
fork()ing a subshell and fork()+exec()ing 'cat' several times.

Use the 'read' bash builtin instead to avoid those overheads.

Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>

diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index 0563dea8ae588cd3504340214cf32d53c5e91092..bc402f56b223a4b96fa378674412eac47ee3b3b3 100644 (file)
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh
@@ -325,9 +325,9 @@ __git_ps1 ()
        local step=""
        local total=""
        if [ -d "$g/rebase-merge" ]; then
-               b="$(cat "$g/rebase-merge/head-name" 2>/dev/null)"
-               step=$(cat "$g/rebase-merge/msgnum" 2>/dev/null)
-               total=$(cat "$g/rebase-merge/end" 2>/dev/null)
+               read b 2>/dev/null <"$g/rebase-merge/head-name"
+               read step 2>/dev/null <"$g/rebase-merge/msgnum"
+               read total 2>/dev/null <"$g/rebase-merge/end"
                if [ -f "$g/rebase-merge/interactive" ]; then
                        r="|REBASE-i"
                else
@@ -335,10 +335,10 @@ __git_ps1 ()
                fi
        else
                if [ -d "$g/rebase-apply" ]; then
-                       step=$(cat "$g/rebase-apply/next" 2>/dev/null)
-                       total=$(cat "$g/rebase-apply/last" 2>/dev/null)
+                       read step 2>/dev/null <"$g/rebase-apply/next"
+                       read total 2>/dev/null <"$g/rebase-apply/last"
                        if [ -f "$g/rebase-apply/rebasing" ]; then
-                               b="$(cat "$g/rebase-apply/head-name" 2>/dev/null)"
+                               read b 2>/dev/null <"$g/rebase-apply/head-name"
                                r="|REBASE"
                        elif [ -f "$g/rebase-apply/applying" ]; then
                                r="|AM"