Bash Scripting Question

wahming · 10-04-2010, 10:15 PM

I'm writing a script that relaunches itself with root permissions. It starts like this:

#!/bin/sh

CMDLN_ARGS="$@"
if [ $UID -ne 0 ]; then
echo 'Please enter root password'
echo su root -c "$0 $CMDLN_ARGS"
echo su root -c "$0 $@"
exec su root -c "$0 $CMDLN_ARGS"
fi

In this case, it works fine. However, if I replace $CMDLN_ARGS in the exec line with $@, it breaks for multiple input arguments. But the echo statements tell me that both lines should be identical. What gives? I can get my script to work, but I'd really like to understand the issue here.

murugesan · 10-05-2010, 01:16 AM

The arguments passed to the script needs to be passed using double quotes:

Code:

scriptname.sh "/bin/ls -ltr"

http://www.geocities.ws/murugesan/te...g/passArg.html

wahming · 10-05-2010, 03:55 AM

Thanks. But assuming I want the script to handle it gracefully, instead of the user modifying his input? I've tried quoting my input \"$@\" in script but it doesn't work.

konsolebox · 10-05-2010, 04:01 AM

if it's bash it should be like this:

Code:

#!/bin/bash

CMDLN_ARGS=("$@")
if [[ $UID -ne 0 ]]; then
    echo 'Please enter root password'
    echo su root -c "$0" "${CMDLN_ARGS[@]}"
    echo su root -c "$0" "$@"
    exec su root -c "$0" "${CMDLN_ARGS[@]}"
fi

You might also find -n useful:

Code:

    echo -n 'Please enter root password: '

murugesan · 10-05-2010, 04:31 AM

Updated code using $@:

Using ksh (USEksh.sh)

Code:

#!/bin/ksh
CMDLN_ARGS="$@"
if [[ $UID -ne 0 ]]; then
    echo -n 'Please enter root password'
    echo su root -c "$0" "${CMDLN_ARGS[@]}"
    echo su root -c "$0" "$@"
    exec su root -c "$0 $@"
else
        echo  You cab execute: $@ : if required
        #$@
fi

Using bash(USEbash.sh)

Code:

#!/bin/bash
CMDLN_ARGS="$@"
if [[ $UID -ne 0 ]]; then
    echo -n 'Please enter root password'
    echo su root -c "$0" "${CMDLN_ARGS[@]}"
    echo su root -c "$0" "$@"
    exec su root -c "$0 $@"
else
        echo  You cab execute: $@ : if required
        #$@
fi

Example usage:

Code:

USEksh.sh ls -latr
USEbash.sh ls -latr

http://www.geocities.ws/murugesan/te...g/passArg.html