join

Join on first field

$ join [file1] [file2]

$ join -1 [2] -2 [1] [file1] [file2]

$ join -o 1.1,2.2 [file1] [file2]

$ join -i [file1] [file2]

$ join -a 1 [file1] [file2]

$ join -t "," [file1.csv] [file2.csv]

join [options] file1 file2

join merges two files on a common field. It performs relational database-style joins on text files.
Files must be sorted on the join field. The tool supports inner, left, and right join operations.
join merges files on common field.

FILE1 FILE2

Files to join (must be sorted on join field).

Join on field N of file 1.

Join on field N of file 2.

Output format specification.

Field delimiter.

Ignore case differences.

Print unpairable lines.

Display help information.

Files must be sorted. Field-based joining. Default whitespace delimiter.

join is part of POSIX and traditional Unix utilities, providing relational join operations on text files.

sort(1), cut(1), paste(1), awk(1)