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shell程式設計的for和while迴圈

1. for迴圈

  語法1:for NAME [in WORDS ... ] ; do COMMANDS; done

#!/bin/bash
if
[[ $# -lt 1 ]] ; then echo no param!!!; exit; fi for a in "[email protected]" ; do echo hello$a > ${a} ; done

如果引數的個數小於1,直接退出。否則把hello+引數名依次重定向到引數名作為檔名的檔案。

[email protected]:命令列所有的引數

  語法2:for (( exp1; exp2; exp3 )) do COMMANDS; done

for (( a=1 ; a  < 11 ; a = a + 1 )) ; do echo $a ; done

迴圈列印1到10

2while迴圈

  語法1:while COMMANDS; do COMMANDS; done

  語法2: (( exp1))

      while (( exp2 )) ; do

        COMMANDS

        (( exp3 ))

      done

#!/bin/bash
(( count = $# ))
(( a = 1 ))
while (( a <= count )) ; do
    echo
$1; shift; (( a = a+1 )) done

迴圈列印命令的引數

$#:命令的引數個數;

shift:引數左移一位