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9. User interfaces

9.1 Using select to make simple menus

      #!/bin/bash
      OPTIONS="Hello Quit"
      select opt in $OPTIONS; do
     if [ "$opt" = "Quit" ]; then
   echo done
   exit
     elif [ "$opt" = "Hello" ]; then
   echo Hello World
     else
   clear
   echo bad option
     fi
      done
     

If you run this script you'll see that it is a programmer's dream for text based menus. You'll probably notice that it's very similar to the 'for' construction, only rather than looping for each 'word' in $OPTIONS, it prompts the user.

9.2 Using the command line

     #!/bin/bash   
     if [ -z "$1" ]; then 
    echo usage: $0 directory
    exit
     fi
     SRCD=$1
     TGTD="/var/backups/"
     OF=home-$(date +%Y%m%d).tgz
     tar -cZf $TGTD$OF $SRCD
    

What this script does should be clear to you. The expression in the first conditional tests if the program has received an argument ($1) and quits if it didn't, showing the user a little usage message. The rest of the script should be clear at this point.