join连接字段

 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