"Shell" Linux Shell's while loop

While and for are circular statements, relative, the For loop uses a bit more. But the while loop is especially useful when reading a file line.

While format

while [ 条件 ]do    内容done

Example: Determine if I is small and equal to 5, if less than or equal to 5 prints the value of I

i=1while [ $i -le 5 ]do        echo $i        i=$(($i+1))done

[Email protected] scripts]# bash while.sh
1
2
3
4
5

Use while to read the number of file rows

#!/bin/bash -while read linedo         echo $linedone<a.txt

[Email protected] scripts]# bash whileline.sh
lll
222
333
444
555
666

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"Shell" Linux Shell's while loop