Bash-Beginners-Guide

Bash Guide for Beginners
case EXPRESSION in CASE1) COMMAND-LIST;; CASE2) COMMAND-LIST;; ... CASEN)
COMMAND-LIST;; esac
Each case is an expression matching a pattern. The commands in the COMMAND-LIST for the first match
are executed. The "|" symbol is used for separating multiple patterns, and the ")" operator terminates a pattern
list. Each case plus its according commands are called a clause. Each clause must be terminated with ";;".
Each case statement is ended with the esac statement.
In the example, we demonstrate use of cases for sending a more selective warning message with the
disktest.sh script:
anny ~/testdir> cat disktest.sh
#!/bin/bash
# This script does a very simple test for checking disk space.
space=`df -h | awk '{print $5}' | grep % | grep -v Use | sort -n | tail -1 | cut -d "%" -f1 -`
case $space in
[1-6]*)
Message="All is quiet."
;;
[7-8]*)
Message="Start thinking about cleaning out some stuff. There's a partition that is $space % fu
;;
9[1-8])
Message="Better hurry with that new disk... One partition is $space % full."
;;
99)
Message="I'm drowning here! There's a partition at $space %!"
;;
*)
Message="I seem to be running with an nonexistent amount of disk space..."
;;
esac
echo $Message | mail -s "disk report `date`" anny
anny ~/testdir>
You have new mail.
anny ~/testdir> tail -16 /var/spool/mail/anny
From anny@octarine Tue Jan 14 22:10:47 2003
Return-Path:
Received: from octarine (localhost [127.0.0.1])
by octarine (8.12.5/8.12.5) with ESMTP id h0ELAlBG020414
for ; Tue, 14 Jan 2003 22:10:47 +0100
Received: (from anny@localhost)
by octarine (8.12.5/8.12.5/Submit) id h0ELAltn020413
for anny; Tue, 14 Jan 2003 22:10:47 +0100
Date: Tue, 14 Jan 2003 22:10:47 +0100
From: Anny
Message-Id:
To: anny@octarine
Subject: disk report Tue Jan 14 22:10:47 CET 2003
Start thinking about cleaning out some stuff. There's a partition that is 87 % full.
anny ~/testdir>
Chapter 7. Conditional statements 91