{
    "mode": "man",
    "parameter": "crontab",
    "section": "1",
    "url": "https://www.chedong.com/phpMan.php/man/crontab/1/json",
    "generated": "2026-09-04T03:35:09Z",
    "synopsis": "crontab [ -h]\ncrontab [ -u user ] [-n] file\ncrontab [ -u user ] [ -i ] { -e | -l | -r }",
    "sections": {
        "NAME": {
            "content": "crontab - maintain crontab files for individual users (Vixie Cron)\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "crontab [ -h]\ncrontab [ -u user ] [-n] file\ncrontab [ -u user ] [ -i ] { -e | -l | -r }\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "crontab  is  the  program  used  to  install,  deinstall or list the tables used to drive the\ncron(8) daemon in Vixie Cron.  Each user can have their own crontab,  and  though  these  are\nfiles in /var/spool/cron/crontabs, they are not intended to be edited directly.\n\nIf  the  /etc/cron.allow  file exists, then you must be listed (one user per line) therein in\norder to be allowed to use this command.  If the /etc/cron.allow file does not exist but  the\n/etc/cron.deny file does exist, then you must not be listed in the /etc/cron.deny file in or‐\nder to use this command.\n\nIf  neither of these files exists, then depending on site-dependent configuration parameters,\nonly the super user will be allowed to use this command, or all users will  be  able  to  use\nthis command.\n\nIf  both  files exist then /etc/cron.allow takes precedence.  Which means that /etc/cron.deny\nis not considered and your user must be listed in /etc/cron.allow in order to be able to  use\nthe crontab.\n\nRegardless of the existence of any of these files, the root administrative user is always al‐\nlowed to setup a crontab.  For standard Debian systems, all users may use this command.\n\nIf the -h option is given, crontab shows a help message and quits immediately.\n\nIf  the  -u  option  is  given, it specifies the name of the user whose crontab is to be used\n(when listing) or modified (when editing).  If this option is  not  given,  crontab  examines\n\"your\"  crontab,  i.e., the crontab of the person executing the command.  Note that su(8) can\nconfuse crontab and that if you are running inside of su(8) you should always use the -u  op‐\ntion for safety's sake.\n\nThe first form of this command is used to install a new crontab from some named file or stan‐\ndard input if the pseudo-filename ``-'' is given.\n\nIf  the  -n option is given, it means \"dry run\": crontab examines \"your\" crontab for its syn‐\ntax, and outputs a success message if this syntax is correct, but nothing is written  to  any\ncrontab.\n\nThe  -l  option  causes the current crontab to be displayed on standard output.  See the note\nunder DEBIAN SPECIFIC below.\n\nThe -r option causes the current crontab to be removed.\n\nThe -e option is used to edit the current crontab using the editor specified by the VISUAL or\nEDITOR environment variables.  After you exit from the editor, the modified crontab  will  be\ninstalled  automatically.   If  neither of the environment variables is defined, then the de‐\nfault editor /usr/bin/editor is used.\n\nThe -i option modifies the -r option to prompt the user for a 'y/Y' response before  actually\nremoving the crontab.\n",
            "subsections": []
        },
        "DEBIAN SPECIFIC": {
            "content": "The  \"out-of-the-box\" behaviour for crontab -l is to display the three line \"DO NOT EDIT THIS\nFILE\" header that is placed at the beginning of the crontab when it is installed.  The  prob‐\nlem is that it makes the sequence\n\ncrontab -l | crontab -\n\nnon-idempotent  — you keep adding copies of the header.  This causes pain to scripts that use\nsed to edit a crontab.  Therefore, the default behaviour of the -l option has been changed to\nnot output such header.  You may obtain the original behaviour  by  setting  the  environment\nvariable  CRONTABNOHEADER to 'N', which will cause the crontab -l command to emit the extra‐\nneous header.\n\nHIGHLIGHTING THE OUTPUT of crontab -l\nThe command crontab -l outputs plain text. When a tty can support ANSI sequences to colourise\nthis text, one can highlight the output, by calling: crontab -l | spc -t crontab when the tty\nbackground is dark, or crontab -l | spc -t crontab-light when this background is light.\n\nThe highlighting scheme can be modified by using customised  versions  of  files  /etc/super‐\ncat/spcrc-crontab*\n\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "crontab(5), cron(8), spc(1)\n",
            "subsections": []
        },
        "FILES": {
            "content": "/etc/cron.allow\n/etc/cron.deny\n/var/spool/cron/crontabs\n\nThe files /etc/cron.allow and /etc/cron.deny if they exist, must be either world-readable, or\nreadable by group ``crontab''. If they are not, then cron will deny access to all users until\nthe permissions are fixed.\n\nThere  is  one  file  for  each  user's crontab under the /var/spool/cron/crontabs directory.\nUsers are not allowed to edit the files under that directory directly  to  ensure  that  only\nusers  allowed  by the system to run periodic tasks can add them, and only syntactically cor‐\nrect crontabs will be written there.  This is enforced by having the directory writable  only\nby  the  crontab  group and configuring crontab command with the setgid bid set for that spe‐\ncific group.\n",
            "subsections": []
        },
        "STANDARDS": {
            "content": "The crontab command conforms to IEEE Std1003.2-1992 (``POSIX'').   This  new  command  syntax\ndiffers from previous versions of Vixie Cron, as well as from the classic SVR3 syntax.\n\n",
            "subsections": []
        },
        "DIAGNOSTICS": {
            "content": "A fairly informative usage message appears if you run it with a bad command line.\n\ncron  requires that each entry in a crontab end in a newline character.  If the last entry in\na crontab is missing the newline, cron will consider the crontab (at least partially)  broken\nand refuse to install it.\n\nThe files under /var/spool/cron/crontabs are named based on the user's account name.  Crontab\njobs  will not be run for users whose accounts have been renamed either due to changes in the\nlocal system or because they are managed through a central user  database  (external  to  the\nsystem, for example an LDAP directory).\n\n\n",
            "subsections": []
        },
        "AUTHOR": {
            "content": "Paul  Vixie  <paul@vix.com>  is  the author of cron and original creator of this manual page.\nThis page has also been modified for Debian by Steve Greenland, Javier Fernandez-Sanguino and\nChristian Kastner.\n\n4th Berkeley Distribution                   19 April 2010                                 CRONTAB(1)",
            "subsections": []
        }
    },
    "summary": "crontab - maintain crontab files for individual users (Vixie Cron)",
    "flags": [],
    "examples": [],
    "see_also": [
        {
            "name": "cron",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/cron/8/json"
        },
        {
            "name": "spc",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/spc/1/json"
        }
    ],
    "tldr": {
        "source": "official",
        "description": "Schedule cron jobs to run on a time interval for the current user.",
        "examples": [
            {
                "description": "[e]dit the crontab file for the current user",
                "command": "crontab -e"
            },
            {
                "description": "[e]dit the crontab file for a specific [u]ser",
                "command": "sudo crontab -e -u {{user}}"
            },
            {
                "description": "Replace the current crontab with the contents of the given file",
                "command": "crontab {{path/to/file}}"
            },
            {
                "description": "[l]ist existing cron jobs for the current user",
                "command": "crontab -l"
            },
            {
                "description": "[r]emove all cron jobs for the current user",
                "command": "crontab -r"
            },
            {
                "description": "Sample cron job which runs at 10:00 every day (* means any value)",
                "command": "0 10 * * * {{command_to_execute}}"
            },
            {
                "description": "Sample cron job which runs a command every 10 minutes",
                "command": "*/10 * * * * {{command_to_execute}}"
            },
            {
                "description": "Sample cron job which runs a certain script at 02:30 every Friday",
                "command": "30 2 * * Fri /{{path/to/script.sh}}"
            }
        ]
    }
}