Processing arguments
Processing arguments that are passed via a script's command line is as simple as follows. Say we had this script:
$ cat cmd.bash #!/bin/bash echo "arg1: $1" echo "arg2: $2" Now run with no arguments:
$ ./cmd.bash arg1: arg2: With 1 argument:
$ ./cmd.bash hi arg1: hi arg2: With 2 arguments:
$ ./cmd.bash hi bye arg1: hi arg2: bye Checking the arguments
You can then check if the arguments, 1 & 2, are valid directories or not, and then bail out or proceed as needed. So we introduce 2 checks to see if the 2 arguments are directories or not, if not then exit.
$ cat cmd.bash #!/bin/bash [ -d "$1" ] || exit [ -d "$2" ] || exit [ $# == 2 ] || exit echo "arg1: $1" echo "arg2: $2" Example
Say we have these directories.
$ mkdir d1 d2 $ ls -l total 12 -rwxrwxr-x. 1 saml saml 89 Oct 14 23:13 cmd.bash drwxrwxr-x. 2 saml saml 4096 Oct 14 23:14 d1 drwxrwxr-x. 2 saml saml 4096 Oct 14 23:14 d2 If we are given anything other than 2 directories, the script will simply exit.
$ ./cmd.bash hi bye If we're given 2 directories:
$ ./cmd.bash d1 d2 arg1: d1 arg2: d2 If we're given more than 2 arguments:
$ ./cmd.bash d1 d2 d3 I'll leave the comparison of the 2 directories to you. For learning Bash I'd direct you to the link below for a free online book on Bash.