-while Application Example of shell application

Like other languages, loops are also script patterns in the shell

One. Grammar:

     while  [expression]
                 do
                  operation ...
                 done

As long as the expression in [] is set, it will continue to loop. Notice that there is a space between [] and the expression. The process is to first determine whether the expression is ture or false. The comparison of the values in the while expression is:

EQ: equivalent =; GE: equivalent to >=; Le : equivalent to <=; NE: equals ! =;

GT: equivalent to >, lt is equivalent to:<;

Print a multiplication table, small instance.

——————————————————————————

#!/bin/bash

#author Zhao

#test for ' while '

I=0

B=1

While [$i-lt 9];

Do

Let I+=1

While [$b-le $i]

Do

Let z= $b * $i

Echo-ne "$b" * "$i" = "$z" "\ T"

Let B+=1

Done

Let B=1

Echo-e "\ n"

Done

————————————————————————————————————

The effect shown is:

1*1=1

1*2=2 2*2=4

1*3=3 2*3=6 3*3=9

1*4=4 2*4=8 3*4=12 4*4=16

1*5=5 2*5=10 3*5=15 4*5=20 5*5=25

1*6=6 2*6=12 3*6=18 4*6=24 5*6=30 6*6=36

1*7=7 2*7=14 3*7=21 4*7=28 5*7=35 6*7=42 7*7=49

1*8=8 2*8=16 3*8=24 4*8=32 5*8=40 6*8=48 7*8=56 8*8=64

1*9=9 2*9=18 3*9=27 4*9=36 5*9=45 6*9=54 7*9=63 8*9=72 9*9=81

*****

The above is a simple instance of while.

Suitable for rookie,,, to see and see.

This article is from the "Wen Zhao" blog, please be sure to keep this source http://zhaowencheng.blog.51cto.com/7821671/1653886

-while Application Example of shell application