Identifier / Programs / Linux and Unix
comm
Select or reject lines common to two files. Both files must be sorted. tldr-pages
GTFOBins file-read 1 documented command
How comm is abused
file-read
Each abuse is GTFOBins's category and the options and words it uses; the full write-up is on GTFOBins's page for comm.
1 documented command
file-read unprivileged, with sudo, as SUID
A newline is appended to the file.
comm /path/to/input-file /dev/nullThe command the identifier reads trips no Sigma process-creation rule. This command is, with GTFOBins’ notes, from GTFOBins, at commit acd524623f9c of 2026-05-27, under the GPL-3.0, with no warranty. Changed: Markdown is shown formatted. The source is in lolbas-gtfobins-commands.json.gz, and the full entry is on GTFOBins’s page for comm. The identifier reads the line that runs comm.
Everyday use
Produce three tab-separated columns: lines only in first file, lines only in second file, and common lines
comm file1 file2IdentifyPrint only lines common to both files
comm -12 file1 file2IdentifyPrint only lines common to both files, reading one file from stdin
cat file1 | comm -12 - file2IdentifyNone of the 3 examples the identifier reads matches GTFOBins abuse or trips a Sigma process-creation rule.
Options
Show every option of comm
-1Suppress the output column of lines unique to FILE1-2Suppress the output column of lines unique to FILE2-3Suppress the output column of lines duplicated in FILE1 and FILE2