shell学习五----变量子串

1、内置命令 [root@node01 ~]# which cd /usr/bin/which: no cd in (/data/apache-maven-3.3.9/bin:/usr/lib64/qt-3.3/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin) [root@node01 ~]# man cd BASH_BUILTINS(1)                                              BASH_BUILTINS(1) NAME        bash, :, ., [, alias, bg, bind, break, builtin, caller, cd, command, compgen, complete, compopt, continue, declare, dirs, disown, echo, enable,        eval, exec, exit, export, false, fc, fg, getopts, hash, help, history, jobs, kill, let, local, logout, mapfile, popd, printf, pushd, pwd, read,        readonly, return, set, shift, shopt, source, suspend, test, times, trap, true, type, typeset, ulimit, umask, unalias, unset, wait - bash built-        in commands, see bash(1) 2、变量子串常用操作（了解） man bash找本节资料 ${#string}                         打印$string的长度 ${#string:position}                在$string中，从位置%position之后开始提取字串        ${#string:position:length}         在$string中，从位置%position之后开始提取长度为$length的字串 例子： [root@node01 ~]# WOLF="hello yujing" [root@node01 ~]# echo $WOLF hello yujing [root@node01 ~]# echo ${#WOLF}        和wc -L 相同 12 [root@node01 ~]# echo $WOLF |wc  -L   12 root@node01 ~]# echo ${WOLF:2}       llo yujing [root@node01 ~]# echo ${WOLF:2:2}  ll [root@node01 ~]# echo ${WOLF:2:4}  和cut -c相同 llo [root@node01 ~]# echo $WOLF |cut -c 3-4 ll [root@node01 ~]# echo $WOLF |cut -c 3-6 llo  删除 ${#string#substring}                  从变量$string开头开始删除最短匹配$substring子串 ${#string##substring}                 从变量$string开头开始删除最长匹配$substring子串 ${#string%substring}                  从变量$string结尾开始删除最短匹配$substring子串 ${#string%%substring}                 从变量$string结尾开始删除最长匹配$substring子串 替换 ${#string/substring/replace}          使用$replace,来代替第一个匹配的$substring ${#string/#substring/replace}         如果$string前缀匹配$substring,用$replace来代替匹配substring ${#string/%substring/replace}         如果$string后缀匹配$substring,用$replace来代替匹配substring 例子： [root@node01 ~]# WOLF="hello yujing" hello yujing [root@node01 ~]# echo ${WOLF/yujing/laolang} hello laolang 实例： 1、通过变量子串替换 vi laolang.log wolf_20170806_1_wolf.jpg wolf_20170806_2_wolf.jpg wolf_20170806_3_wolf.jpg wolf_20170806_4_wolf.jpg wolf_20170806_5_wolf.jpg wolf_20170806_6_wolf.jpg wolf_20170806_7_wolf.jpg wolf_20170806_8_wolf.jpg wolf_20170806_9_wolf.jpg wolf_20170806_10_wolf.jpg [root@node01 data]# touch `cat laolang.log |tr "\n" " "` [root@node01 data]# ll total 8316 drwxr-xr-x 6 root root    4096 Jul  8 07:24 apache-maven-3.3.9 -rw-r--r-- 1 root root 8491533 Jul  8 07:23 apache-maven-3.3.9-bin.tar.gz -rw-r--r-- 1 root root       0 Jul 29 14:16 cat drwxr-xr-x 2 root root    4096 Jul 29 06:00 day1 drwxr-xr-x 2 root root    4096 Jul 29 11:50 day2 drwxr-xr-x 2 root root    4096 Jul 29 14:12 day3 -rw-r--r-- 1 root root     251 Jul 29 14:16 laolang.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_10_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_1_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_2_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_3_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_4_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_5_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_6_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_7_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_8_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_9_wolf.jpg [root@node01 data]# f=wolf_20170806_10_wolf.jpg [root@node01 data]# echo $f wolf_20170806_10_wolf.jpg [root@node01 data]# echo ${f%wolf*.jpg} wolf_20170806_10_ [root@node01 data]# mv $f `echo ${f%wolf*.jpg}.jpg` [root@node01 data]# ll total 8316 drwxr-xr-x 6 root root    4096 Jul  8 07:24 apache-maven-3.3.9 -rw-r--r-- 1 root root 8491533 Jul  8 07:23 apache-maven-3.3.9-bin.tar.gz -rw-r--r-- 1 root root       0 Jul 29 14:16 cat drwxr-xr-x 2 root root    4096 Jul 29 06:00 day1 drwxr-xr-x 2 root root    4096 Jul 29 11:50 day2 drwxr-xr-x 2 root root    4096 Jul 29 14:12 day3 -rw-r--r-- 1 root root     251 Jul 29 14:16 laolang.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_10_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_1_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_2_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_3_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_4_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_5_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_6_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_7_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_8_wolf.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_9_wolf.jpg [root@node01 data]# for f in `ls *wolf.jpg` ;do mv $f `echo ${f%wolf*.jpg}.jpg`;done [root@node01 data]# ll total 8316 drwxr-xr-x 6 root root    4096 Jul  8 07:24 apache-maven-3.3.9 -rw-r--r-- 1 root root 8491533 Jul  8 07:23 apache-maven-3.3.9-bin.tar.gz -rw-r--r-- 1 root root       0 Jul 29 14:16 cat drwxr-xr-x 2 root root    4096 Jul 29 06:00 day1 drwxr-xr-x 2 root root    4096 Jul 29 11:50 day2 drwxr-xr-x 2 root root    4096 Jul 29 14:12 day3 -rw-r--r-- 1 root root     251 Jul 29 14:16 laolang.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_10_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_1_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_2_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_3_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_4_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_5_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_6_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_7_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_8_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_9_.jpg 2、修改扩展名 把上面的jpg更换为log [root@node01 data]# f=wolf_20170806_10_.jpg [root@node01 data]# echo ${f/%jpg/log}  wolf_20170806_10_.log [root@node01 data]# mv $f ${f/%jpg/log}       [root@node01 data]# ls apache-maven-3.3.9             day1  laolang.log            wolf_20170806_2_.jpg  wolf_20170806_5_.jpg  wolf_20170806_8_.jpg apache-maven-3.3.9-bin.tar.gz  day2  wolf_20170806_10_.log  wolf_20170806_3_.jpg  wolf_20170806_6_.jpg  wolf_20170806_9_.jpg cat                            day3  wolf_20170806_1_.jpg   wolf_20170806_4_.jpg  wolf_20170806_7_.jpg [root@node01 data]# ll total 8316 drwxr-xr-x 6 root root    4096 Jul  8 07:24 apache-maven-3.3.9 -rw-r--r-- 1 root root 8491533 Jul  8 07:23 apache-maven-3.3.9-bin.tar.gz -rw-r--r-- 1 root root       0 Jul 29 14:16 cat drwxr-xr-x 2 root root    4096 Jul 29 06:00 day1 drwxr-xr-x 2 root root    4096 Jul 29 11:50 day2 drwxr-xr-x 2 root root    4096 Jul 29 14:12 day3 -rw-r--r-- 1 root root     251 Jul 29 14:16 laolang.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_10_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_1_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_2_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_3_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_4_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_5_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_6_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_7_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_8_.jpg -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_9_.jpg [root@node01 data]# for f in `ls *.jpg` ;do mv $f ${f/%jpg/log} ;done [root@node01 data]# ll total 8316 drwxr-xr-x 6 root root    4096 Jul  8 07:24 apache-maven-3.3.9 -rw-r--r-- 1 root root 8491533 Jul  8 07:23 apache-maven-3.3.9-bin.tar.gz -rw-r--r-- 1 root root       0 Jul 29 14:16 cat drwxr-xr-x 2 root root    4096 Jul 29 06:00 day1 drwxr-xr-x 2 root root    4096 Jul 29 11:50 day2 drwxr-xr-x 2 root root    4096 Jul 29 14:12 day3 -rw-r--r-- 1 root root     251 Jul 29 14:16 laolang.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_10_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_1_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_2_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_3_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_4_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_5_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_6_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_7_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_8_.log -rw-r--r-- 1 root root       0 Jul 29 14:16 wolf_20170806_9_.log ====================================================================== 网上资料 http://blog.csdn.net/github_33736971/article/details/53980123 ${#string}  返回$string的长度 ${string:position}  在$string中，从$position位置之后开始提取子串 ${string:position:length}  在$string中，从$position位置之后开始提取$length长度的子串 [root@localhost SHELL]# NAME="ni hao, ming tian" [root@localhost SHELL]# echo $NAME ni hao, ming tian [root@localhost SHELL]# echo ${NAME} ni hao, ming tian [root@localhost SHELL]# echo ${#NAME} 17 [root@localhost SHELL]# echo ${NAME:3} hao, ming tian [root@localhost SHELL]# echo ${NAME:3:6} hao, m [root@localhost SHELL]#  ${string#substring}  从变量$string开头开始删除最短匹配$substring子串 ${string##substring}  从变量$string开头开始删除最长匹配$sunstring子串 [root@localhost SHELL]# echo $NAME abcABC123ABCabcde [root@localhost SHELL]# echo ${NAME#a*C} 123ABCabcde [root@localhost SHELL]# echo ${NAME##a*C} abcde [root@localhost SHELL]#  ${string%substring}  从变量$string结尾开始删除最短匹配$substring子串 ${string%%substring}  从变量$string结尾开始删除最长匹配$substring子串 [root@localhost SHELL]# NAME=abcABC123ABCabc [root@localhost SHELL]# echo $NAME abcABC123ABCabc [root@localhost SHELL]# echo ${NAME%%a*c} [root@localhost SHELL]# echo ${NAME%a*c} abcABC123ABC [root@localhost SHELL]# echo ${NAME#b*c} abcABC123ABCabc [root@localhost SHELL]# echo ${NAME#bc} abcABC123ABCabc [root@localhost SHELL]# echo ${NAME