join

Join lines of two sorted files on a common field.

• Join two files on the first (default) field:

join {{file1}} {{file2}}

• Join two files using a comma (instead of a space) as the field separator:

join -t {{','}} {{file1}} {{file2}}

• Join field3 of file1 with field1 of file2:

join -1 {{3}} -2 {{1}} {{file1}} {{file2}}

• Produce a line for each unpairable line for file1:

join -a {{1}} {{file1}} {{file2}}