32v 1m comm
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COMM(1) UNIX Programmer's Manual COMM(1)
comm - select or reject lines common to two sorted files
comm [ - [ 123 ] ] file1 file2
_C_o_m_m reads _f_i_l_e_1 and _f_i_l_e_2, which should be ordered in ASCII collating sequence, and produces a three column output: lines only in _f_i_l_e_1; lines only in _f_i_l_e_2; and lines in both files. The filename `-' means the standard input.
Flags 1, 2, or 3 suppress printing of the corresponding column. Thus comm -12 prints only the lines common to the two files; comm -23 prints only lines in the first file but not in the second; comm -123 is a no-op.