Linux命令：for循环写法总结

Posted 2020-08-21

for循环写法总结

关于shell中的for循环用法很多，感觉很全面，所以就转过来研究研究，嘿嘿...

  1、 for((i=1;i<=10;i++))

[[email protected] ~]# for ((i=1;i<3;i++ )); do echo $(($i*4)); done
4
8

  2、在shell中常用的是 for i in $(seq 10)

[[email protected] ~]# for i in $(seq 2); do echo $(($i*4)); done
4
8

  3、for i in {1..10}

[[email protected] ~]# for i in {1..2}; do echo $(($i*4)); done
4
8

  4、for i in stringchar {1..10}

[[email protected] ~]# for i in user{1..2}; do echo $i; done
user1
user2

  5、for i in `ls`

[[email protected] ~]# for i in `ls`; do echo $i; done

  6、for i in f1 f2 f3 ;do

[[email protected] ~]# for i in 2 8 20; do echo $(($i*4)); done
8
32
80

  7、for i in *.txt

[[email protected] ~]# for i in *.txt ;do echo $i ; done    #相当于ls *.txt
second.txt
userinfo.txt

  8、for i in $(ls *.txt)   #利用` `或$( )的将多行合为一行，实际是合为一个字符串数组

[[email protected] ~]# for i in $(ls *.txt) ;  do echo $i ;   done
second.txt
userinfo.txt

  9、for i in $* ; do      #  $*表示脚本输入的所有参数

  10、for i in ${arr[@]} 

  11、for File in /proc/sys/net/ipv4/conf/*/accept_redirects; do

  13、awk ‘BEGIN{for(i=1; i<=10; i++) print i}‘  #AWK中的for循环写法和C语言一样的

  12、用for in语句自动对字符串按空格遍历的特性，对多个目录遍历

LIST="rootfs usr data data2"

for d in $LIST; do 

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