Contrary to many programming languages, if you want to test for equality in a shell script you must only use the equals sign once.
Try to keep this in mind: under a shell that implements what is required by POSIX:2001, you may hit the unexpected in the following code.
if [ foo == foo ]; then
echo expected
else
echo unexpected
fi
Of course debian has a few offenders as well..
ReplyDeletehttp://codesearch.debian.net/search?q=\[.*%3D%3D+filetype%3Ashell
My regulars expressions arent that good :)
Maybe you can come up with a better one
Auto file this kind of bugs with gift tag would be awesome... even tho it might not be easy
http://codesearch.debian.net/search?q=%5C%5B%5B%5E%5D%5D*%3D%3D+filetype%3Ashell
DeleteSee https://www.mirbsd.org/man7/re_format (scroll down to “BASIC REGULAR EXPRESSIONS”)
Which leads us to even more weird things:
if [ $# == 2 -a $my_nunlinks != $2 ]
“-a” is not portable, though a very common extension. Fix:
if [ $# -eq 2 ] && [ x"$my_nunlinks" != x"$2" ]
#bashism: [ "${i:0:1}" == "/" ] || i=$(which $i)
Commented out, how nice. Fix:
case $i in /*) ;; *) i=$(which "$i") ;; esac
if [[ $(id -u) == 0 ]] ; then
It doesn’t say if this is mksh or GNU bash. mksh has $USER_ID which eliminates the need to fork’n’exec; GNU bash probably has the same. Plus, even within the Korn shell construct of [[ … ]] “==” is not always allowed (though, in all recent shells that interpret it).
if [ "" == "$1" ]; then
This is pretty ouch. What happened to [ -z "$1" ] or even [ "$1" ] || …? And it’s a GNU bash script, they should be using [[ anyway.
@pajarodebian: that's what we have checkbashisms for :) it does a bit more than just running regexes.
Delete@Thorsten: hey, it's one bashism a week, don't spoil some of the upcoming posts :)
http://codesearch.debian.net/search?q=%5C%5B%5B%5E%5D%5D*%3D%3D+filetype%3Ashell
ReplyDeleteSee https://www.mirbsd.org/man7/re_format (scroll down to “BASIC REGULAR EXPRESSIONS”)