Section: User Contributed Perl Documentation (1)
shell-quote - quote arguments for safe use, unmodified in a shell command
lets you pass arbitrary strings through the shell so that
they won't be changed by the shell. This lets you process commands or
files with embedded white space or shell globbing characters safely.
Here are a few examples.
- ssh preserving args
When running a remote command with ssh, ssh doesn't preserve the separate
arguments it receives. It just joins them with spaces and passes them to
"$SHELL -c". This doesn't work as intended:
ssh host touch 'hi there' # fails
It creates 2 files, hi and there. Instead, do this:
cmd=`shell-quote touch 'hi there'`
ssh host "$cmd"
This gives you just 1 file, hi there.
- process find output
It's not ordinarily possible to process an arbitrary list of files
output by find with a shell script. Anything you put in $IFS to
split up the output could legitimately be in a file's name. Here's how
you can do it using shell-quote:
eval set -- `find -type f -print0 | xargs -0 shell-quote --`
- debug shell scripts
shell-quote is better than echo for debugging shell scripts.
[ -z "$debug" ] || shell-quote "debug:" "$@"
With echo you can't tell the difference between "debug 'foo bar'"
and "debug foo bar", but with shell-quote you can.
- save a command for later
shell-quote can be used to build up a shell command to run later.
Say you want the user to be able to give you switches for a command
you're going to run. If you don't want the switches to be re-evaluated
by the shell (which is usually a good idea, else there are things the
user can't pass through), you can do something like this:
while [ $# != 0 ]
case x$1 in
[ $# -gt 1 ] || die "need an argument for $1"
user_switches="$user_switches "`shell-quote -- "$2"`
# process other switches
eval "shell-quote some-command $user_switches my args"
Turn debugging on.
Show the usage message and die.
Show the version number and exit.
The code is licensed under the GNU GPL.
for updated versions.
Roderick Schertler <firstname.lastname@example.org