this command compare two sorted files line by line and write to standard output
$ comm file1 file 2
compare two sorted files
$ comm numbers.txt file.txt
3rd column is suppressed
$ comm -3 numbers.txt file.txt
check whethet the input files are sorted or not
$ comm --check order file.txt list.txt
displays bytes in the output
$ comm -b file1.txt file2.txt
it compares the files without sorting
$ comm no check order file1 pavani.txt
compare file names of two directories
comm <(ls file.txt) <(ls file1.txt)
ignore the case sensitivity with -i
comm -i words.txt colors.txt
write text to directly compare with colors.txt
$ comm colors.txt -
does not print the columns having the commonn lines
$ comm -3 colors.txt names.txt