[PATCH 14/15] git-am.sh: replace using expr for arithmetic operations with the equivalent shell builtin

[Elia Pinto <gitter.spiros@gmail.com>]

expr is considered generally antiquated. It is best to use for arithmetic operations
the shell $((..)).

To quote POSIX:

"The expr utility has a rather difficult syntax [...] In many cases, the arithmetic
and string features provided as part of the shell command language are easier to use
than their equivalents in expr. Newly written scripts should avoid expr in favor of
the new features within the shell."

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
---
 git-am.sh | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/git-am.sh b/git-am.sh
index ee61a77..4f8148e 100755
--- a/git-am.sh
+++ b/git-am.sh
@@ -298,7 +298,7 @@ split_patches () {
 		this=0
 		for stgit in "$@"
 		do
-			this=$(expr "$this" + 1)
+			this=$(( "$this" + 1 ))
 			msgnum=$(printf "%0${prec}d" $this)
 			# Perl version of StGIT parse_patch. The first nonemptyline
 			# not starting with Author, From or Date is the
@@ -656,14 +656,14 @@ last=$(cat "$dotest/last")
 this=$(cat "$dotest/next")
 if test "$skip" = t
 then
-	this=$(expr "$this" + 1)
+	this=$(( "$this" + 1 ))
 	resume=
 fi
 
 while test "$this" -le "$last"
 do
 	msgnum=$(printf "%0${prec}d" $this)
-	next=$(expr "$this" + 1)
+	next=$(( "$this" + 1 ))
 	test -f "$dotest/$msgnum" || {
 		resume=
 		go_next
-- 
2.5.0