Shell's Process Control

One, if statement, while, for loop a variety of small examples

1. User authentication

[[email protected] ~]# cat buer.sh #!/bin/bash#user= ' buer ' #password = ' 1234.com ' read-p ' please your name: ' Userread-p ' pas Sword: ' passwdif [$user = ' Buer '-a $passwd = ' 1234.com '];then    echo ' login successful ' fi

2. Guess the Age

#!/bin/bashage=57read-p ' num: ' numif [$num-eq $age];then    echo ' Get it ' elif [$num-gt $age];then    Echo ' to o Big ' elif [$num-lt $age];then    echo ' too samll ' fi

3. Search results

[email protected] ~]# cat score.sh #!/bin/bashread-p ' Please your score: ' Scoreif [$score-ge];then    Echo ' very good! ' elif [$score-ge 70-a $score-lt];then    echo ' good! ' elif [$score-ge 60-a $score-lt];then    echo ' Just like ' else    echo ' poor ' fi

4.for Cycle Printing 1235

[[email protected] ~]# cat for.sh #!/bin/bashfor i in {1..5}do    if ((i = = 4)] Then        continue        #break    Fi
   echo ' ======= ' $idone

Execution results for script 4:

[Email protected] ~]#/for.sh ======= 1======= 2======= 3======= 5

5. Improved version of guessing age

[email protected] ~]# cat oldboy.sh oldboy=57while:d o    read-p ' input your Age: ' Age    if [-Z $age];then        cont Inue    fi    if [$age-eq $oldboy];then        echo "Bingo"        break    elif [$age-lt $oldboy];then        echo "Littl E "    elif [$age-gt $oldboy];then        echo" Big "    else        echo" Bye "    Fidone

Script 5 results:

6. View File types

[email protected] ~]# cat aa.sh #!/bin/bashwhile:d o    read-p ' input your file: ' File    if [-Z $file];then        con  Tinue    elif [$file = ' quit '];then        break    fi    If [-B $file];then        echo "$file is block file"    elif [ -D $file];then        echo "$file is directory file"    Elif [-F $file];then        echo "$file is regular file"    Els E        echo "$file unkown"    fidone

Script 6 Results:

[Email protected] ~]# sh aa.sh input your file:/etc/    etc is directory fileinput your file:/pm/pm unkowninput your fi Le:quit

7. Printing multiplication Tables

[[email protected] ~]# cat cheng.sh #!/bin/bashfor ((i=1;i<=9;i++)) do for    ((j=1;j<=i;j++)) do    Echo-n "$i * $j =$[$i * $j]"    done    Echodone

Script 7 results:

[Email protected] ~]#/cheng.sh 1*1=12*1=22*2=43*1=33*2=63*3=94*1=44*2=84*3=124*4=165*1=55*2=105*3=155*4=205*5= 256*1=66*2=126*3=186*4=246*5=306*6=367*1=77*2=147*3=217*4=287*5=357*6=427*7=498*1=88*2=168*3=248*4=328*5=408*6 =488*7=568*8=649*1=99*2=189*3=279*4=369*5=459*6=549*7=639*8=729*9=81

8. Create users in batches

[[email protected] ~]# cat add.sh #!/bin/bashfor i in {1..5};d o    useradd user$i && echo "user$i create SUCCESSF UL "Done

Script 8 Execution Results:

[[Email protected] ~]# sh add.sh user1 create successfuluser2 Create Successfuluser3 create successfuluser4 Create success FULUSER5 Create successful

9. Delete users in bulk

[[email protected] ~]# cat del.sh #!/bin/bashfor i in {1..5};d o     userdel-r user$i && echo "user$i Delete Succe Ssful "Done

Script 9 Execution Results:

[[Email protected] ~]# sh del.sh user1 delete successfuluser2 Delete successfuluser3 Delete successfuluser4 Delete success FULUSER5 Delete Successful

10. Loop overlay to print the numbers and sleep 1s

[[email protected] ~]# cat conut.sh #!/bin/bashcount=1while (Count <) do    echo ' ==========> ' $count    Sleep 1    ((count+=1)) done

Execution Result:

[[Email protected] ~]# sh conut.sh ==========> 1==========> 2==========> 3==========> 4==========> 5===== =====> 6==========> 7==========> 8==========> 9

11. Batch Ping IP

[email protected] ~]# cat ping.sh #!/bin/bashfor i in {1..100};d o    ping-c1 192.168.16. $i &>/dev/null    If [ $? -eq 0];then        echo "192.168.16. $i OK"        echo "192.168.16. $i" >>/tmp/ip.txt    Fidone

12. Impersonate a login user gadget

[email protected] ~]# cat login.sh #!/bin/bashuser= ' buer ' passwd= ' 1234.com ' while $tagdo    read-p ' input your name: ' NA Me    read-p ' input your passwd: ' pas    if [[$name = $user]] && [[$pas = $passwd]];then        echo ' login su Ccessful '        while $tag        do            read-p ' >>: ' cmd            if [[$cmd = ' quit ']];then                tag=false            Else                $cmd            fi        done    fidone

Execution Result:

[Email protected] ~]# sh login.sh input your name:buerinput your passwd:1234.comlogin successful>>:lsaa.sh         A.txt       del.sh         oldboy.sh  template  download add.sh         buer.sh   for.sh         ping.sh    video  Music age.sh         cheng.sh  initial-setup-ks.cfg  score.sh   picture  desktop anaconda-ks.cfg  conut.sh  login.sh         Public        

Shell's Process Control