JOIN(1) JOIN(1) join - join []... 1 2 . . FILE1 FILE2 ( ) - . -a _ _ _ 1 2 1 2 -e () '-12jo' -i, --ignore-case -j '-1 -2 ' -o -t -v _ -a _ -1 1 -2 2 --check-order --nocheck-order --header -z, --zero-terminated NUL --help --version -t . 1. '_.' '0'. 1 2 . 'auto' . : FILE1 FILE2 . "sort -k 1b,1" 'join' "join -t "" 'sort' . 'LC_COLLATE'. . . : bug-coreutils@gnu.org GNU coreutils : : (C) 2026 (Free Software Foundation, Inc.). GPLv3+: GNU GPL 3 . . : . . comm(1) uniq(1) : info '(coreutils) join invocation' 3 . . : . GNU coreutils 9.11 2026 JOIN(1)