Reduce repeating of commands in bash script

Question

I'm working on a bash script to increase /tmp on a VPS server and I'd like to make it cleaner/more efficient without the need to repeat the same commands for whichever option is picked. Here's how it's structured right now:

#!/bin/bash

  showMenu () {
        echo "1) Increase /tmp size to 1 GB"
        echo "2) Increase /tmp size to 2 GB"
        echo "3) Quit"
}
   while [ 1 ]
   do
       showMenu
       read CHOICE
       case "$CHOICE" in

  "1")
       /etc/init.d/mysql stop
       /etc/init.d/httpd stop
       /etc/init.d/cpanel stop
       cp -af /var/tmp /var/tmp.bak
       umount -l /var/tmp
       umount -l /tmp
       rm -f /usr/tmpDSK
       dd if=/dev/zero of=/usr/tmpDSK bs=1M count=1k
       mkfs.ext3 -F /usr/tmpDSK
       mount -t ext3 -o nosuid,noexec,loop /usr/tmpDSK /tmp
       mount -o bind,noexec,nosuid /tmp /var/tmp
       cp -a /var/tmp.bak/* /tmp/
       rm -rf /var/tmp.bak/
       chmod 1777 /tmp
       /etc/init.d/mysql start
       /etc/init.d/httpd start
       /etc/init.d/cpanel start
       df -h
       exit 1
       ;;

    "2")
       /etc/init.d/mysql stop
       /etc/init.d/httpd stop
       /etc/init.d/cpanel stop
       cp -af /var/tmp /var/tmp.bak
       umount -l /var/tmp
       umount -l /tmp
       rm -f /usr/tmpDSK
       dd if=/dev/zero of=/usr/tmpDSK bs=1M count=2k
       mkfs.ext3 -F /usr/tmpDSK
       mount -t ext3 -o nosuid,noexec,loop /usr/tmpDSK /tmp
       mount -o bind,noexec,nosuid /tmp /var/tmp
       cp -a /var/tmp.bak/* /tmp/
       rm -rf /var/tmp.bak/
       chmod 1777 /tmp
       /etc/init.d/mysql start
       /etc/init.d/httpd start
       /etc/init.d/cpanel start
       df -h
       exit 1
       ;;

    "3")
        exit 1
       ;;
      esac
    done

I basically want to only initiate the redundant commands once during this process. Can you give me an idea or ideas on the best way to do this?

Thanks.

This is strange. The code already demonstrates knowledge and a good example of a function. Why not leverage that knowledge? — wallyk, Jul 06 '12 at 20:15

score 2 · Answer 1 · answered Jul 06 '12 at 20:13

2

Sounds like a good fit for a bash function. Put the meat of the code in a function and then pass a parameter for the size.

answered Jul 06 '12 at 20:13

Alex Howansky

50,515
8
78
98

You're right. I knew it was something like that, but couldn't remember the name. Looks much better now :) – Striketh Jul 06 '12 at 20:21

score 1 · Answer 2 · answered Jul 06 '12 at 20:14

1

This is what functions are for. Put your common code in a function and call it from the appropriate case selections. An alternative is to set flags in your case statement and do conditional execution based on the flags.

answered Jul 06 '12 at 20:14

Dennis Williamson

346,391
90
374
439

score 1 · Accepted Answer · answered Jul 06 '12 at 20:15

#!/bin/bash

function size_up {
           /etc/init.d/mysql stop
           /etc/init.d/httpd stop
           /etc/init.d/cpanel stop
           cp -af /var/tmp /var/tmp.bak
           umount -l /var/tmp
           umount -l /tmp
           rm -f /usr/tmpDSK
           dd if=/dev/zero of=/usr/tmpDSK bs=1M count=${1}k
           mkfs.ext3 -F /usr/tmpDSK
           mount -t ext3 -o nosuid,noexec,loop /usr/tmpDSK /tmp
           mount -o bind,noexec,nosuid /tmp /var/tmp
           cp -a /var/tmp.bak/* /tmp/
           rm -rf /var/tmp.bak/
           chmod 1777 /tmp
           /etc/init.d/mysql start
           /etc/init.d/httpd start
           /etc/init.d/cpanel start
           df -h
           exit 1
           ;;
}



function showMenu () {
        echo "1) Increase /tmp size to 1 GB"
        echo "2) Increase /tmp size to 2 GB"
        echo "3) Quit"
}
 while [ 1 ]
   do
    showMenu
    read CHOICE
    case "$CHOICE" in
       "1") size_up 1
       "2") size_up 2
       "3") exit 1
       ;;
    esac
done

Thanks for writing it out. I ended up doing it myself, but giving the answer to you for the extra effort. — Striketh, Jul 06 '12 at 20:21

score 0 · Answer 4 · answered Jul 06 '12 at 23:20

0

Note that bash functions are a little weird.

function abc
{
   global_var=1
}

function def
(
   local_var=1
)

Note the curly braces vs parens. With the parens, your function is run in a subshell, while with the curly braces, your function does not get a unique namespace!

answered Jul 06 '12 at 23:20

user1277476

2,871
12
10

It doesn't answer the question but it's good to know! see http://stackoverflow.com/questions/2188199/bash-double-or-single-bracket-parentheses-curly-braces – Luc M Jul 07 '12 at 04:10

Reduce repeating of commands in bash script

4 Answers4