The while loop of the shell loop structure

While loop

1)

While CONDITION; Do

Statement

Statement

< change the loop condition true and false statement >

Done

Write a script that calculates 1---100 of the AND

#!/bin/bash

#

Sum=0

I=1

While [$i-le 100]; Do

Let sum= $sum + $i

Let i= $i +1

Done

Echo $sum

2)

While true; Do

Statement

Statement

Done

#!/bin/bash

#

While true; Do

Read-p "Please enter your choice:" Choice

if [$choice = = "Q"]; Then

Break

Fi

Done

#!/bin/bash

#

While true; Do

Uptime

Sleep 3

Done

3)

while read line; Do

Statement

Statement

Done < file

#!/bin/bash

#

Bash_num=0

Nologin_num=0

while read line; Do

sh_name=$ (echo $line | awk-f: ' {print $7} ')

Case $sh _name in

/bin/bash)

Let bash_num= $bash _num+1

;;

/sbin/nologin)

Let nologin_num= $nologin _num+1

;;

Esac

Done </etc/passwd

Echo $bash _num

Echo $nologin _num

Util cycle:

Util CONDITION; Do

Statement

Statement

Done

When the condition is false, the loop is executed and the condition is true, ending the loop

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The while loop of the shell loop structure