{
    "mode": "man",
    "parameter": "crontab",
    "section": "1",
    "url": "https://www.chedong.com/phpMan.php/man/crontab/1/json",
    "generated": "2026-06-13T21:37:36Z",
    "synopsis": "crontab [ -u user ] 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 [ -u user ] 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  -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\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",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "crontab(5), cron(8)\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,\nor readable by group ``crontab''. If they are not, then cron will deny access  to  all  users\nuntil the 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\n\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"
        }
    ],
    "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}}"
            }
        ]
    }
}