#

| Chapter 22 File Security, Ownership, and Sharing |

## 22.10 cx, cw, c-w: Quick File Permission Changes

Here's a short script that I use a lot. To make a new shell script executable, for example, I type:

>     % cx scriptfile

Using cw adds write permission; c-w takes it away. This is the single script file for all three commands:

>     #! /bin/sh
>     case "$0" in
>     *cx)  chmod +x "$@" ;;
>     *cw)  chmod +w "$@" ;;
>     *c-w) chmod -w "$@" ;;
>     *)    echo "$0: Help!  Shouldn't get here!" 1>&2; exit 1 ;;
>     esac

The script has three links. Put it in a file named cx. Then type:

>     % chmod +x cx
>     % ln cx cw
>     % ln cx c-w

The script tests the name it was called with, in `$0`, to decide which chmod command to run. This trick saves disk space. You can add other commands, too, by adding a line to the case and another link. Or you can use aliases (22.9).

- JP

22.9 Protect Important Files: Make Them Unwritable |  | 22.11 A Loophole: Modifying Files Without Write Access