CASE statements are similir to ELIF statements, use case if elif statements are more than 3.
1case expression in
2 pattern1 )
3 statements ;;
4 pattern2 )
5 statements
6 ;;
7esac
Exactly how you use fi to end if statements, you close a case statement with esac (which is the alphabetic opposite of case, case spelled backwards).
;; marks the end of a statement.
Example:
1echo -n "give me a domain: "
2read domain
3
4case $domain in
5 "google.com" )
6 echo "Google, wow!" ;;
7 "twitter.com" )
8 echo "Twitter -_-" ;;
9 "udemy.com" )
10 echo "Udemy, YES!" ;;
11 "aamnah.com" )
12 echo "Aamnah.com, brilliant. Let's PING!"
13 ping -c3 aamnah.com ;;
14esac
1case "$1" in
2 start)
3 /usr/sbin/sshd
4 ;;
5 stop)
6 kill $(cat /var/run/sshd.pid)
7 ;;
8esac
In the example above if $1 is equal to start then /usr/sbin/sshd is executed. If $1 is equal to stop then the kill command is executed. If $1 matches neither start nor stop then nothing happens and the script continues after the statement.
Note: case statements (start and stop in the example above) are case-sensitive.
1case "$1" in
2 start)
3 /usr/sbin/sshd
4 ;;
5 stop)
6 kill $(cat /var/run/sshd.pid)
7 ;;
8 *)
9 echo "Usage start|stop"
10 exit 1
11 ;;
12esac
In this example, anything other than start or stop will show usage instructions.
*1*)
2 echo "Usage start|stop"
3 exit 1
4 ;;
is the same as
1*)
2 echo "Usage start|stop" ; exit 1
3 ;;
|You can use pipe | to seperate multiple case statement conditions/options. | servers as OR
1case "$1" in
2 start|START)
3 /usr/sbin/sshd
4 ;;
5 stop|STOP)
6 kill $(cat /var/run/sshd.pid)
7 ;;
8 *)
9 echo "Usage start|stop"
10 exit 1
11 ;;
12esac
[]Character classes are simply a list of characters between brackets []. Like so:
1[yY][nN]
A character class matches exactly one character, and a match occurs for any of the including characters in the brackets.
1[yY][eE][sS]
will check for all case-sensitive possibilities of yes. yes, Yes, yEs, yeS, YEs, yES, YeS, and so on.. Here’s a code example:
1read -p "Enter y or n: " ANSWER
2
3case "$ANSWER" in
4 [yY]|[yY][eE][sS] )
5 echo "You answered yes." ;;
6 [nN]|[nN][oO] )
7 echo "You answered no." ;;
8 * )
9 echo "Invalid answer." ;;
10esac