Linux Shell Learning Three

Shell for Loop

The syntax for the Shell for loop is as follows

 for inch List  Do     command1    command2    ... CommandN Done

Example:

 for inch {1..  - }  do      echo  $i   Done  

Class C language is also possible

 for ((i=1; i<=; i + +))    do      Echo $i    Done  

Shell while loop

 while Command  Do If True done     

Example:

counter=0while5  ]do    COUNTER='expr $ Counter+1'    echo  $COUNTER Done

Description: Returns True if counter is less than 5. Counter starting from 0, each time the loop is processed, counter plus 1, until count is 5 terminates.

Shell until loop

until Command  Do Until true done     

Example:

#!/bin/basha=0until [! $a-lt]do   echo $a   a= ' expr $a + 1 ' done

Note: When the "A is not less than 10" condition is false, the loop executes the command in the circulating body, that is, when a is greater than or equal to 10 o'clock, it will jump out of the loop body.

This script will output 0-9 numbers.

　

Linux Shell Learning Three