[PATCH 04/10] contrib/examples/git-merge.sh: don't use the -a or -o option with the test command

Even though POSIX.1 lists -a/-o as options to "test", they are marked "Obsolescent XSI". Scripts using these expressions should be converted as follow:

test "$1" -a "$2"

should be written as:

test "$1" && test "$2"

Likewise

test "$1" -o "$2"

should be written as:

test "$1"  test "$2"

But note that, in test, -a has higher precedence than -o while "&&" and "||" have equal precedence in the shell.

The reason for this is that the precedence rules were never well specified, and this made many sane-looking uses of "test -a/-o" problematic.

For example, if $x is "=", these work according to POSIX (it's not portable, but in practice it's okay):

   $ test -z "$x"
   $ test -z "$x" && test a = b

but this doesn't

   $ test -z "$x" -a a = b
   bash: test: too many arguments

because it groups "test -n = -a" and is left with "a = b".

Similarly, if $x is "-f", these

   $ test "$x"
   $ test "$x" || test c = d

correctly adds an implicit "-n", but this fails:

   $ test "$x" -o c = d
   bash: test: too many arguments

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
---
Inspired from this discussion http://permalink.gmane.org/gmane.comp.version-control.git/137056

 contrib/examples/git-merge.sh |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)