运维日志

join命令可以讲多个相同字段的文件结合到一起

NAME
       join - join lines of two files on a common field

SYNOPSIS
       join [OPTION]... FILE1 FILE2

DESCRIPTION
       For each pair of input lines with identical join fields, write a line to standard output.  The default join field is the first,
       delimited by whitespace.  When FILE1 or FILE2 (not both) is -, read standard input.

       -a FILENUM
              print unpairable lines coming from file FILENUM, where FILENUM is 1 or 2, corresponding to FILE1 or FILE2

       -e EMPTY
              replace missing input fields with EMPTY

       -i, --ignore-case ignore differences in case when comparing fields

       -j FIELD
              equivalent to ?.1 FIELD -2 FIELD?

       -o FORMAT
              obey FORMAT while constructing output line

       -t CHAR
              use CHAR as input and output field separator

       -v FILENUM
              like -a FILENUM, but suppress joined output lines

       -1 FIELD
join on this FIELD of file 1

       -2 FIELD
              join on this FIELD of file 2

       --help display this help and exit

       --version
              output version information and exit

[root@localhost shell]# cat tt1
test	100
test1	80
test2	90
[root@localhost shell]# cat tt2
test	yingyu
test1	shuxue
test2	yuwen
[root@localhost shell]# join tt1 tt2
test 100 yingyu
test1 80 shuxue
test2 90 yuwen

sed 创建目录结构。

 find /shell/a/ -type d -print | sed 's;/shell/a/;/shell/b/;' | sed 's/^/mkdir /'
mkdir /shell/b/
mkdir /shell/b/p

find 查找目录， -type 是指定类型为目录，并打印出来

sed 's;/shell/a/;/shell/b/;' 修改名称，这里使用分号做为定界符

sed 's/^mkdir /'  插入mkdir 命令

也可以使用后向引用：

[root@localhost shell]# find /shell/ -type d -print | sed 's;/\(shell\)/a/;\1/c/;' |sed 's/^/mkdir /'
mkdir /shell/
mkdir /shell/a
mkdir shell/c/p
mkdir /shell/b
mkdir /shell/b/p

[root@localhost shell]# grep ^root passwd
root:x:0:0:root:/root:/bin/bash
[root@localhost shell]# sed -n '\:root: s;;Root;p' passwd
Root:x:0:0:root:/root:/bin/bash

改变定界符，以:开始查找的模式，而分号为扮演s命令的定界符角色

[root@localhost shell]# echo "123" | sed 's/1*/b/'    #替换第一个匹配成的
b23

[root@localhost shell]# echo "123" | sed 's/1*/b/g'    #替换所有匹配成功的
b2b3b