[PATCH] contrib/git-prompt.sh: handle missing 'printf -v' more gracefully

From: Brandon Casey <redacted>

Old Bash (3.0) which is distributed with RHEL 4.X and other ancient
platforms that are still in wide use, do not have a printf that
supports -v.  Neither does Zsh (which is already handled in the code).

As suggested by Junio, let's test whether printf supports the -v
option and store the result.  Then later, we can use it to
determine whether 'printf -v' can be used, or whether printf
must be called in a subshell.

Signed-off-by: Brandon Casey <redacted>
---


On 8/21/2013 6:27 PM, Junio C Hamano wrote:> Brandon Casey [off-list ref] writes:

quoted

Why is "${var-}" necessary?  Wouldn't that be equivalent to "${var}"
or "$var"?

set -u

Ah.  Thanks.  Updated.  Also minor tweak to use [ ] instead of test ...
to conform with the rest of the script.

-Brandon


 contrib/completion/git-prompt.sh | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index a81ef5a..ca7fb35 100644
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh

@@ -84,6 +84,10 @@
 # the colored output of "git status -sb" and are available only when
 # using __git_ps1 for PROMPT_COMMAND or precmd.
 
+# check whether printf supports -v
+__git_printf_supports_v=
+printf -v __git_printf_supports_v -- '%s' yes >/dev/null 2>&1
+
 # stores the divergence from upstream in $p
 # used by GIT_PS1_SHOWUPSTREAM
 __git_ps1_show_upstream ()

@@ -433,10 +437,10 @@ __git_ps1 ()
 	local gitstring="$c${b##refs/heads/}${f:+$z$f}$r$p"
 
 	if [ $pcmode = yes ]; then
-		if [[ -n ${ZSH_VERSION-} ]]; then
-			gitstring=$(printf -- "$printf_format" "$gitstring")
-		else
+		if [ "${__git_printf_supports_v-}" = yes ]; then
 			printf -v gitstring -- "$printf_format" "$gitstring"
+		else
+			gitstring=$(printf -- "$printf_format" "$gitstring")
 		fi
 		PS1="$ps1pc_start$gitstring$ps1pc_end"
 	else

-- 
1.8.4.rc0.2.g6cf5c31


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