{
"content": [
{
"type": "text",
"text": "# COMM (man)\n\n## NAME\n\ncomm - compare two sorted files line by line\n\n## SYNOPSIS\n\ncomm [OPTION]... FILE1 FILE2\n\n## DESCRIPTION\n\nCompare sorted files FILE1 and FILE2 line by line.\n\n## TLDR\n\n> Select or reject lines common to two files. Both files must be sorted.\n\n- Produce three tab-separated columns: lines only in first file, lines only in second file, and common lines:\n `comm {{file1}} {{file2}}`\n- Print only lines common to both files:\n `comm -12 {{file1}} {{file2}}`\n- Print only lines common to both files, reading one file from `stdin`:\n `cat {{file1}} | comm -12 - {{file2}}`\n- Get lines only found in first file, saving the result to a third file:\n `comm -23 {{file1}} {{file2}} > {{file1_only}}`\n- Print lines only found in second file, when the files aren't sorted:\n `comm -13 <(sort {{file1}}) <(sort {{file2}})`\n\n*Source: tldr-pages*\n\n## Sections\n\n- **NAME**\n- **SYNOPSIS**\n- **DESCRIPTION** (8 subsections)\n- **EXAMPLES**\n- **AUTHOR**\n- **REPORTING BUGS**\n- **COPYRIGHT**\n- **SEE ALSO**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n"
}
],
"structuredContent": {
"command": "COMM",
"section": "",
"mode": "man",
"summary": "comm - compare two sorted files line by line",
"synopsis": "comm [OPTION]... FILE1 FILE2",
"tldr_summary": "Select or reject lines common to two files. Both files must be sorted.",
"tldr_examples": [
{
"description": "Produce three tab-separated columns: lines only in first file, lines only in second file, and common lines",
"command": "comm {{file1}} {{file2}}"
},
{
"description": "Print only lines common to both files",
"command": "comm -12 {{file1}} {{file2}}"
},
{
"description": "Print only lines common to both files, reading one file from `stdin`",
"command": "cat {{file1}} | comm -12 - {{file2}}"
},
{
"description": "Get lines only found in first file, saving the result to a third file",
"command": "comm -23 {{file1}} {{file2}} > {{file1_only}}"
},
{
"description": "Print lines only found in second file, when the files aren't sorted",
"command": "comm -13 <(sort {{file1}}) <(sort {{file2}})"
}
],
"tldr_source": "official",
"flags": [
{
"flag": "-1",
"long": null,
"arg": null,
"description": ""
},
{
"flag": "-2",
"long": null,
"arg": null,
"description": ""
},
{
"flag": "-3",
"long": null,
"arg": null,
"description": ""
},
{
"flag": "",
"long": "--check-order",
"arg": null,
"description": "check that the input is correctly sorted, even if all input lines are pairable"
},
{
"flag": "",
"long": "--nocheck-order",
"arg": null,
"description": "do not check that the input is correctly sorted --output-delimiter=STR separate columns with STR"
},
{
"flag": "",
"long": "--total",
"arg": null,
"description": "output a summary"
},
{
"flag": "-z",
"long": "--zero-terminated",
"arg": null,
"description": "line delimiter is NUL, not newline --help display this help and exit"
},
{
"flag": "",
"long": "--version",
"arg": null,
"description": "output version information and exit Note, comparisons honor the rules specified by 'LCCOLLATE'."
}
],
"examples": [
"comm -12 file1 file2",
"Print only lines present in both file1 and file2.",
"comm -3 file1 file2",
"Print lines in file1 not in file2, and vice versa."
],
"see_also": [
{
"name": "join",
"section": "1",
"url": "https://www.chedong.com/phpMan.php/man/join/1/json"
},
{
"name": "uniq",
"section": "1",
"url": "https://www.chedong.com/phpMan.php/man/uniq/1/json"
}
],
"section_outline": [
{
"name": "NAME",
"lines": 2,
"subsections": []
},
{
"name": "SYNOPSIS",
"lines": 2,
"subsections": []
},
{
"name": "DESCRIPTION",
"lines": 8,
"subsections": [
{
"name": "-1",
"lines": 1,
"flag": "-1"
},
{
"name": "-2",
"lines": 1,
"flag": "-2"
},
{
"name": "-3",
"lines": 1,
"flag": "-3"
},
{
"name": "--check-order",
"lines": 2,
"long": "--check-order"
},
{
"name": "--nocheck-order",
"lines": 5,
"long": "--nocheck-order"
},
{
"name": "--total",
"lines": 2,
"long": "--total"
},
{
"name": "-z --zero-terminated",
"lines": 4,
"flag": "-z",
"long": "--zero-terminated"
},
{
"name": "--version",
"lines": 4,
"long": "--version"
}
]
},
{
"name": "EXAMPLES",
"lines": 6,
"subsections": []
},
{
"name": "AUTHOR",
"lines": 2,
"subsections": []
},
{
"name": "REPORTING BUGS",
"lines": 3,
"subsections": []
},
{
"name": "COPYRIGHT",
"lines": 5,
"subsections": []
},
{
"name": "SEE ALSO",
"lines": 8,
"subsections": []
}
],
"sections": {
"NAME": {
"content": "comm - compare two sorted files line by line\n",
"subsections": []
},
"SYNOPSIS": {
"content": "comm [OPTION]... FILE1 FILE2\n",
"subsections": []
},
"DESCRIPTION": {
"content": "Compare sorted files FILE1 and FILE2 line by line.\n\nWhen FILE1 or FILE2 (not both) is -, read standard input.\n\nWith no options, produce three-column output. Column one contains lines unique to FILE1,\ncolumn two contains lines unique to FILE2, and column three contains lines common to both\nfiles.\n",
"subsections": [
{
"name": "-1",
"content": "",
"flag": "-1"
},
{
"name": "-2",
"content": "",
"flag": "-2"
},
{
"name": "-3",
"content": "",
"flag": "-3"
},
{
"name": "--check-order",
"content": "check that the input is correctly sorted, even if all input lines are pairable\n",
"long": "--check-order"
},
{
"name": "--nocheck-order",
"content": "do not check that the input is correctly sorted\n\n--output-delimiter=STR\nseparate columns with STR\n",
"long": "--nocheck-order"
},
{
"name": "--total",
"content": "output a summary\n",
"long": "--total"
},
{
"name": "-z --zero-terminated",
"content": "line delimiter is NUL, not newline\n\n--help display this help and exit\n",
"flag": "-z",
"long": "--zero-terminated"
},
{
"name": "--version",
"content": "output version information and exit\n\nNote, comparisons honor the rules specified by 'LCCOLLATE'.\n",
"long": "--version"
}
]
},
"EXAMPLES": {
"content": "comm -12 file1 file2\nPrint only lines present in both file1 and file2.\n\ncomm -3 file1 file2\nPrint lines in file1 not in file2, and vice versa.\n",
"subsections": []
},
"AUTHOR": {
"content": "Written by Richard M. Stallman and David MacKenzie.\n",
"subsections": []
},
"REPORTING BUGS": {
"content": "GNU coreutils online help: \nReport any translation bugs to \n",
"subsections": []
},
"COPYRIGHT": {
"content": "Copyright © 2020 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later\n.\nThis is free software: you are free to change and redistribute it. There is NO WARRANTY, to\nthe extent permitted by law.\n",
"subsections": []
},
"SEE ALSO": {
"content": "join(1), uniq(1)\n\nFull documentation \nor available locally via: info '(coreutils) comm invocation'\n\n\n\nGNU coreutils 8.32 January 2026 COMM(1)",
"subsections": []
}
}
}
}