Shulou(Shulou.com)06/02 Report--

Structure of case statements

Execute different command sequences for different values of variables

case Variable Value in //variable value is $variable name pattern 1) command sequence 1;; //double semicolon ending statement pattern 2) command sequence 2;; //double semicolon ending statement...... *) Default command sequence esaccase statement execution flow

case statement application demo [root@localhost opt]# vim demo01.sh#!/ bin/bashread -p "Please enter the score (0-100) : " keycase $key in [8-9][0-9]| 100) echo "Your grades are excellent" ;; 7[0-9]) echo "Your grades are good" ;; 6[0-9]) echo "Your grades pass" ;; [0-9]|[1-5][0-9]) echo "Your grades are unqualified" ;; *) echo "The grade you entered is incorrect, please re-enter"esac[root@localhost opt]# source demo01.sh Please enter grade (0-100) : 88 Your grade is excellent [root@localhost opt]# source demo01.sh Please enter grade (0-100) : 76 Your grade is good [root@localhost opt]# source demo01.sh Please enter grade (0-100) : 66 Your score passed [root@localhost opt]# source demo01.sh Please enter your score (0-100) : 59 Your score failed [root@localhost opt]# source demo01.sh Please enter your score (0-100) : 120 The score you entered is incorrect, please re-enter the structure of the for statement

Read different variable values to execute the same set of commands one by one

for variable name in value do command sequence donefor statement execution flow

for statement application demonstration

Add users in batches

1. User names are stored in the users.txt file, one per line

2. The initial password is set to 123456

3. verification script

[root@localhost opt]# vim users.txtSimitaBoke[root@localhost opt]# vim users.sh#!/ bin/bashTMP=$(cat /root/users.txt)for USER in $TMPdo useradd $USER echo "123456" |passwd --stdin $USER &> /dev/nulldone[root@localhost opt]# source users.sh[root@localhost opt]# tail -2 /etc/passwdSimita:x:1030:1030::/home/Simita:/bin/bashBoke:x:1031::/home/Boke:/bin/bashwhile sentence structure

Repeatedly test a condition and repeat it as long as it holds

while Conditional test operation do command sequence donewhile statement execution flow

while statement application demonstration

Guess commodity prices

1. Random number obtained by variable RANDOM

2. Prompt users to guess and record the number of times, guess after exiting the loop

[root@localhost ~]# vim demo08.sh#!/ bin/bashPRICE=$(expr $RANDOM % 1000)TIMES=0 echo "Commodity prices range from 0-999, guess what? "while truedo read -p "Please enter your guess price:" INT let TIMES++if [ $INT -eq $PRICE ];then echo "You guessed it, the actual price is $PRICE" echo "You guessed $TIMES total" exit 0elif [ $INT -gt $PRICE ];then echo "is too high! "else echo "is too low! " fidone[root@localhost ~]# source demo08.sh Commodity prices range from 0-999, guess what? Please enter your guess price:500 is too high! Please enter your guess price:250 is too high! Please enter the number of your guess:200 is too high! Please enter the number of your guess:150 is too low! Please enter the number of your guess:180 is too high! Please enter the number of your guess:160 Too low! Please enter the number of your guess:170 is too high! Please enter the number of your guess:165 Too high! Please enter the number of price you guessed:162 You guessed correctly, the actual price is 162 You guessed a total of 9 times until statement structure

Repeat testing a condition, repeating it as long as the condition is not true

until conditional test operation do command sequence done

until statement application demonstration

Send online messages to specified users

1. If the user is not online (to log in to the system), try every 10 minutes until the user logs in to the system and then send the message

2. The username and message are passed to the script via location parameters

[root@localhost ~]# vim demo01.sh #!/ bin/bashusername=$1#Determine message format if [ $# -lt 1 ];then echo "Usage:`basename $0` []" exit 1fi#Determine if user exists if grep "^$username:" /etc/passwd > /dev/null ;then :else echo "User does not exist"fi#User is online, if not online contact once every five seconds until who| grep "$username" > /dev/null;do echo "User not online" sleep 5donemes=$*echo $mes | write $username[root@localhost ~]# chmod +x demo01.sh[root@localhost ~]# ./ demo01.sh czt After the specified user logs in, the terminal interface receives a message [czt@localhost ~]$ Message from root@localhost.localdomain on pts/0 at 15:09... cztEOF

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