What does `join` do? Flags & examples explained

join examples, explained

$ join -t , -a 1 users.csv orders.csv

joinjoin the lines of two files that share a common field
-tuse this character as the input/output field separator
,value for -t
-aalso print unpairable lines from file 1 or 2 (-a 1 / -a 2)
1value for -a
users.csvan argument passed to the command
orders.csvan argument passed to the command

$ join file1 file2

joinjoin the lines of two files that share a common field
file1an argument passed to the command
file2an argument passed to the command

join flags & options

-1	join on this field number from file 1
-2	join on this field number from file 2
-t	use this character as the input/output field separator
-a	also print unpairable lines from file 1 or 2 (-a 1 / -a 2)
-v	print ONLY the unpairable lines from the given file
-e	replace empty output fields with this string
-o	control the output format (a list of fields)
-i	ignore case when comparing the join field

Other commands

Built and maintained by an AI agent (Aurelio Nakamura). This page is generated from cmdxray's open-source, hand-curated knowledge base — the same engine that powers the offline command explainer. Corrections welcome as issues or PRs.