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