NAME
crontab
—
maintain crontab files for individual
users
SYNOPSIS
crontab |
[-u user]
file |
crontab |
[-e | -l |
-r ] [-u
user] |
DESCRIPTION
crontab
is the program used to install,
deinstall, or list the tables used to drive the
cron(8) daemon. Each user can
have their own crontab(5),
and though these are files in /var/cron/tabs, they
are not intended to be edited directly.
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.
If the /var/cron/cron.allow file
exists, then you must be listed therein in order to use
crontab
. If the
/var/cron/cron.allow file does not exist but the
/var/cron/cron.deny file does exist, then you must
not be listed in the
/var/cron/cron.deny file in order to use
crontab
. If neither of these files exists then only
the super user will be allowed to use crontab
.
NOTE: if
they exist, /var/cron/cron.allow and
/var/cron/cron.deny must be readable by group
crontab. If crontab
is unable to read the files,
users will not be allowed to use crontab
.
The options are as follows:
-e
- Edit the current crontab using the editor specified by the
VISUAL
orEDITOR
environment variables. After you exit from the editor, the modified crontab(5) will be installed automatically. -l
- Causes the current crontab to be displayed on standard output.
-r
- Causes the current crontab to be removed.
-u
user- Specifies the name of the user whose crontab(5) is to be edited. If this option is not given,
crontab
examines “your” crontab(5); i.e., the crontab of the person executing the command. Note that su(1) can confusecrontab
and that if you are running inside of su(1) you should always use the-u
option for safety's sake.
ENVIRONMENT
EDITOR
,VISUAL
- Specifies an editor to use. If both
EDITOR
andVISUAL
are set,VISUAL
takes precedence. If neitherEDITOR
norVISUAL
are set, the default is vi(1).
FILES
- /var/cron/cron.allow
- list of users allowed to use crontab
- /var/cron/cron.deny
- list of users prohibited from using crontab
- /var/cron/tabs
- directory of individual crontabs
SEE ALSO
STANDARDS
The crontab
utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
specification.
The flag [-u
] is an extension to that
specification.
The flag [-e
] is marked by
IEEE Std 1003.1-2008 (“POSIX.1”) as
being optional.
The cron.allow/deny mechanism is marked by IEEE Std 1003.1-2008 (“POSIX.1”) as being an X/Open System Interfaces option.
AUTHORS
Paul Vixie <vixie@isc.org>