Gnu/coreutils/join-invocation
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8.3 join
: Join lines on a common field
join
writes to standard output a line for each pair of input
lines that have identical join fields. Synopsis:
join [option]… file1 file2
Either file1
or file2
(but not both) can be ‘-
’,
meaning standard input. file1
and file2
should be
sorted on the join fields.
$ cat file1 a 1 b 2 e 5 $ cat file2 a X e Y f Z $ join file1 file2 a 1 X e 5 Y
join
’s default behavior (when no options are given):
- the join field is the first field in each line;
- fields in the input are separated by one or more blanks, with leading blanks on the line ignored;
- fields in the output are separated by a space;
- each output line consists of the join field, the remaining fields from
file1
, then the remaining fields fromfile2
.
• General options in join | Options which affect general program behavior. | |
• Sorting files for join | Using sort before join .
| |
• Working with fields | Joining on different fields. | |
• Paired and unpaired lines | Controlling join ’s field matching.
| |
• Header lines | Working with header lines in files. | |
• Set operations | Union, Intersection and Difference of files. |