shell学习五----变量子串

我会带着你远行 2022-06-10 00:50 472阅读 0赞

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%bc\}  
abcABC123ABCa  
\[root@localhost SHELL\]\# echo $\{NAME%%bc\}  
abcABC123ABCa  
\[root@localhost SHELL\]\# echo $\{NAME%C\*c\}  
abcABC123AB  
\[root@localhost SHELL\]\# echo $\{NAME%%C\*c\}  
abcAB  
\[root@localhost SHELL\]\# echo $\{NAME%%C\*b\}  
abcABC123ABCabc  
\[root@localhost SHELL\]\# echo $\{NAME\}  
abcABC123ABCabc  
\[root@localhost SHELL\]\#   
  
注意：在进行\#或\#\#匹配时，$string的首字符必须是被删除子串$substring的第一个字符，不然无法匹配删除；   
在进行%或者%%匹配时，$string的最后一个字符必须是被删除子串$substring的最后一个字符，不然无法进行删除操作；  
  
$\{parameter/parttern/string\}   
用string来替换第一个匹配的pattern  
$\{parameter/\#parttern/string\}   
从开头匹配parameter变量中的pattern，匹配上后就用string来替换匹配的pattern  
$\{parameter/%pattern/string\}   
从结尾开始匹配parameter变量中的pattern，匹配上后就用string替换匹配的pattern  
$\{parameter//pattern/string\}   
用string来替换parameter变量中所有匹配的pattern  
  
\[root@localhost SHELL\]\# NAME="I am a student student"  
\[root@localhost SHELL\]\# echo $\{NAME//student/teacher\}  
I am a teacher teacher  
\[root@localhost SHELL\]\# echo $\{NAME/\#student/teacher\}  
I am a student student  
\[root@localhost SHELL\]\# echo $\{NAME/%student/teacher\}  
I am a student teacher  
\[root@localhost SHELL\]\# echo $\{NAME/%I am /teacher\}  
I am a student student  
\[root@localhost SHELL\]\# echo $\{NAME/\#I am /teacher\}  
teachera student student  
\[root@localhost SHELL\]\# echo $\{NAME/\#I am a/teacher\}  
teacher student student  
\[root@localhost SHELL\]\# echo $NAME  
I am a student student  
\[root@localhost SHELL\]\#   
===========================================================================