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 to256
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
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⟩