Case of multi-branch statement, and shift use

Sometimes a long if statement makes a program very difficult to read, and with a case, you can make the case statement more concise

The case syntax is in the following format:

Case expression inpattern1) suite1;; PATTERN2) Suite2;; ... patternn) Suiten;; *) Other_suite;; Esac

Patterns can be used for each pattern in case:
A|b:a or B
*: matches any character of any length;
?: matches any single character;
[-]: Range matching

Examples of Use:

Write a script that accepts this format
script.sh {Start|stop|restart|status}
1, if start, then create/VAR/LOCK/SUBSYS/SCRIPT.SH, show the success of the start;
2. If the parameter is stop, delete the/var/lock/subsys/script.sh, and the display stops successfully.
3, if restart, then delete, then create, display success;
4, if the status, if the file exists, then display running, otherwise, the display stopped

#!/bin/bashscript=$0lockfile=/var/lock/subsys/script.sh[ $# -lt 1 ] &&  echo  "usage:  $script  {start|stop|restart|staus}"  && exit 6case $1  in  start)         touch  $lockfile          echo  "$script  service start"          ;;   stop)         rm -f  $lockfile          echo  "$script  service stop"          ;;   restart)         rm -f  $lockfile          touch  $lockfile         echo   "$scrtip  service restart"         ;;   status)         if [ -f  $lockfile  ];then           echo  "$script  service is running"          else          echo   "$script  service is stop"         fi         ;;   *)         echo  "usage:  $script  {start|stop| Restart|staus} "                 ;; Esac

Write a simple script
1, prompt the user to enter an arbitrary character;
2, can judge this character is a number, letter or special character;

#!/bin/bash#while true;doread-p "Enter a char:" Char [["$char" = = "Quit"]] && exit 8case $char in [1-9])  echo "$char is digit";;        [A-z])   echo "$char is letter";; *) echo "Special" Esacdone

Write a script that can be packaged and backed up in the/etc/directory, with a backup location of/backup/etc-date. suffix
1. Display the following menu to the user:
XZ) XZ Compress
GZIP) gzip Compress
BIP2) bzip2 Compress
2, according to user-specified compression tool using tar packaging compression;
3, the default is XZ; input errors require the user to re-enter;

#!/bin/bash#dir= "/etc/*" bak= "/backup/etc-" [ -d backup ] | |  MKDIR /BACKUPCAT << EOFXZ)  xz compressgzip)  gzip compressbzip2)  bzip2 compressEOFwhile true;doread -p  "please enter a tool: "  toolstools=${tools:-xz}case  $tools  in  xz)          backuptools=J        end=xz         break        ;;   gzip)         backuptools=z         end=gz        break         ;;   BZIP2)         backuptools=j         end=bz2        break        ;;   *)         echo  "Wrong option,please enter  again "Esacdone tar -c${backuptools}f ${bak} ' date +%f-%t '. $end   $dir

Write a script to complete the following functions
Note: This script can create an alias for the specified network card, specify the address; Use format: Mkethalias.sh-v|--verbose-i|--interface EthX
The 1|-i option is used to specify the NIC;
2, if the network card exists: in the command line, please specify an alias;
3, let the user specify IP and mask;
4. The user can use the-V or--verbose option at the same time: if it is used, the configuration result is displayed after the configuration is completed; otherwise, it is not displayed;

#!/bin/bash#debug=0[ $# -lt 1 ] && echo  "usage: $0 {-v|-- VERBOSE -I|--INTERFACE ETHX} "WHILE [ $# -GE 1 ];d o case $1  In   -v|--verbose)         debug=1         shift 1 ;;    -i|--interface)         interface=$2         shift 2 ;;     *)         echo  "usage: $0 {-v|- -VERBOSE -I|--INTERFACE ETHX} "        shift $*         ;;  esacdone#echo  "$interface   $debug" if ! ip link show  $interface   &> /dev/null;then        echo  "NetworkCard no such "        exit 6firead -p "  enter network_alias:  " network_aliasread -p " PLEASE ENTER IPADDR:   " IPaddrread -p " please enter netmask:  " netmaskip addr add  dev  $interface  ${IPaddr}/${netmask} label  $network _alias[  "$debug"  -eq  1 ] && ip addr show  $interface  | |  echo  "Setup successfuly"

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Case of multi-branch statement, and shift use