CRONTAB(1)

CRONTAB(1) | General Commands Manual | CRONTAB(1)

# NAME

crontab — maintain crontab files for individual users (ISC Cron V4.1)

# SYNOPSIS

crontab | [-u user]

crontab | [-elr]

# DESCRIPTION

crontab is the program used to install, deinstall, or list the tables used to drive the cron(8) daemon in ISC Cron. Each user can have their own crontab, and though these are files in /var/cron, they are not intended to be edited directly.

If the /var/cron/allow file exists, then you must be listed therein in order to be allowed to use this command. If the /var/cron/allow file does not exist but the /var/cron/deny file does exist, then you must not be listed in the /var/cron/deny file in order to use this command. If neither of these files exists, depending on the compiled in settings, only the super user will be allowed to use this command, or everyone will be allowed to use this command. On NetBSD everyone is allowed to use this command.

The default maximum size for a crontab is 256 kilobytes, but this may be changed for all users on the system by putting the desired maximum size (in bytes) in the /var/cron/maxtabsize file.

If the -u option is given, it specifies the name of the user whose crontab is to be tweaked. If this option is not given, crontab examines “your” crontab, i.e., the crontab of the person executing the command. Note that su(1) can confuse crontab and that if you are running inside of su(1) you should always use the -u option for safety's sake.

The first form of this command is used to install a new crontab from some named file or standard input if the pseudo-filename “-” is given.

The -l option causes the current crontab to be displayed on standard output.

The -r option causes the current crontab to be removed.

The -e option is used to edit the current crontab using the editor specified by the VISUAL or EDITOR environment variables. After you exit from the editor, the modified crontab will be installed automatically.

# FILES

/var/cron/allow
  Optional list of users that are allowed to use crontab.
/var/cron/deny
  Optional list of users that are disallowed to use crontab.
/var/cron/maxtabsize
  Maximum size of crontab files. Defaults to 256 kilobytes.
/var/cron/tabs/
  Directory containing the individual user crontab files, named after the user.

# DIAGNOSTICS

A fairly informative usage message appears if you run it with a bad command line.

# SEE ALSO

crontab(5), cron(8)

# STANDARDS

The crontab command conforms to IEEE Std 1003.2 (“POSIX.2”). This new command syntax differs from previous versions of Vixie Cron, as well as from the classic Version 3 AT&T UNIX syntax.

# AUTHORS

Paul Vixie <vixie@isc.org>

May 6, 2010 | NetBSD 7.0