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linuxbashtestingquoting

Bash script: too many arguments in [ test ]

I have the bash script below:

#!/bin/bash
#
[ $# -eq 1 -a $1 = "--help" -o $# -eq 0 ] && {
  echo Help will come here
}

When I run it:

$ ./script 
./script: line 3: [: too many arguments
$ ./script --help
Help will come here

As you can see, when I don't pass parameters ( $# -eq 0 ) it fails with "too many arguments". So, I tested it directly in terminal:

$ a=1;b=2;c=3
$ [ $a -eq 1 -a $b -eq 2 -o $c -eq 3 ] && echo ok
ok
$ [ $a -eq 0 -a $b -eq 2 -o $c -eq 3 ] && echo ok
ok
$ [ $a -eq 0 -a $b -eq 0 -o $c -eq 3 ] && echo ok
ok
$ [ $a -eq 0 -a $b -eq 0 -o $c -eq 0 ] && echo ok
$ [ $a -eq 0 -a $b -eq 2 -o $c -eq 0 ] && echo ok
$ [ $a -eq 1 -a $b -eq 2 -o $c -eq 0 ] && echo ok
ok

So, if it works perfectly in terminal why doesn't it work passing parameters?

Thanks,

Solution

  • Your entire expression can be simplified to:

    function help () {
    printf "%s\n" "help is on it's way."
}

[[ $# -eq 0 || "$*" = "--help" ]] && help ; echo "done." && exit 0 ;

    This checks if the total sum of arguments is zero, or the argument(s) equals "--help". If either of those two things are true then it proceeds to the help function, otherwise echo "done" and exit.