Select or reject lines common to two files (POSIX)
comm [-123] file1 file2
The comm utility reads file1 and file2, which must be ordered in collating sequence (see the sort utility), and produces three text columns as output.
|1||Lines found only in file1|
|2||Lines found only in file2|
|3||Lines found in both files|
Print only the lines common to both files:
comm -12 test.dat save.dat
Standard input is used only if specified as a dash (-) command-line file parameter.
All input files must be text files for comm to produce a meaningful result.
The results of the comparison are written to standard output.
If any errors occur, comm writes diagnostic messages to standard error.
cmp, diff, diff3, sort, uniq