Until cycle __HTML5 of shell programming under Linux

The Until loop and the while loop mean exactly the opposite, while loops indicate that when the conditional expression is true, the loop is continued, and the conditional expression jumps out of the loop when it is false; The until loop indicates that when the conditional expression is false, it loops and ends the loop when the conditional expression is true. In fact, the problem solved with until can be solved by using while and for loops. Similarly, the break and continue keywords are also supported in the Until loop

a cyclic structure

Until [conditional-judgment]
  do
    program block done
  

 

Two usage examples

#!/bin/bash
#Desc for	test while
#Auth	zonggf
#Date	2016-07-02 12:20:21

i=1
Sum=0
until [$i-gt] do
    sum=$ (($sum + $i))
    i=$ (($i + 1)) Done
echo "1+2+3+4+...+10 0= $sum "