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User Commands crontab(1)
NAME
crontab - user crontab file
SYNOPSIS
crontab [filename]
crontab -e [username]
crontab -l [username]
crontab -r [username]
DESCRIPTION
The crontab utility manages a user's access with cron (see
cron(1M)) by copying, creating, listing, and removing cron-
tab files. If invoked without options, crontab copies the
specified file, or the standard input if no file is speci-
fied, into a directory that holds all users' crontabs.
If crontab is invoked with filename, this overwrites an
existing crontab entry for the user that invokes it.
crontab Access Control
Users: Access to crontab is allowed:
o if the user's name appears in /etc/cron.d/cron.allow.
o if /etc/cron.d/cron.allow does not exist and the user's
name is not in /etc/cron.d/cron.deny.
Users: Access to crontab is denied:
o if /etc/cron.d/cron.allow exists and the user's name is
not in it.
o if /etc/cron.d/cron.allow does not exist and user's
name is in /etc/cron.d/cron.deny.
o if neither file exists, only a user with the
solaris.jobs.user authorization is allowed to submit a
job.
o if BSM audit is enabled, the user's shell is not
audited and the user is not the crontab owner. This can
occur if the user logs in by way of a program, such as
some versions of SSH, which does not set audit parame-
ters.
The rules for allow and deny apply to root only if the
allow/deny files exist.
SunOS 5.10 Last change: 10 Nov 2005 1
User Commands crontab(1)
The allow/deny files consist of one user name per line.
crontab Entry Format
A crontab file consists of lines of six fields each. The
fields are separated by spaces or tabs. The first five are
integer patterns that specify the following:
minute (0-59),
hour (0-23),
day of the month (1-31),
month of the year (1-12),
day of the week (0-6 with 0=Sunday).
Each of these patterns can be either an asterisk (meaning
all legal values) or a list of elements separated by commas.
An element is either a number or two numbers separated by a
minus sign (meaning an inclusive range). Time specified here
is interpreted in the timezone of the cron(1M) daemon, which
is set system-wide in /etc/default/init. Entries do not use
the invoking user's timezone. The specification of days can
be made by two fields (day of the month and day of the
week). Both are adhered to if specified as a list of ele-
ments. See EXAMPLES.
The sixth field of a line in a crontab file is a string that
is executed by the shell at the specified times. A percent
character in this field (unless escaped by \) is translated
to a NEWLINE character.
Only the first line (up to a `%' or end of line) of the com-
mand field is executed by the shell. Other lines are made
available to the command as standard input. Any blank line
or line beginning with a `#' is a comment and is ignored.
The shell is invoked from your $HOME directory with an arg0
of sh. Users who desire to have their .profile executed must
explicitly do so in the crontab file. cron supplies a
default environment for every shell, defining HOME, LOGNAME,
SHELL(=/bin/sh), TZ, and PATH. The default PATH for user
cron jobs is /usr/bin; while root cron jobs default to
/usr/sbin:/usr/bin. The default PATH can be set in
/etc/default/cron (see cron(1M)).
If you do not redirect the standard output and standard
error of your commands, any generated output or errors are
mailed to you.
Setting cron Jobs Across Timezones
The timezone of the cron daemon sets the system-wide
timezone for cron entries. This, in turn, is by set by
default system-wide using /etc/default/init.
SunOS 5.10 Last change: 10 Nov 2005 2
User Commands crontab(1)
If some form of daylight savings or summer/winter time is in
effect, then jobs scheduled during the switchover period
could be executed once, twice, or not at all.
OPTIONS
The following options are supported:
-e Edits a copy of the current user's crontab file, or
creates an empty file to edit if crontab does not
exist. When editing is complete, the file is
installed as the user's crontab file. If a username
is given, the specified user's crontab file is
edited, rather than the current user's crontab
file; this can only be done by a user with the
solaris.jobs.admin authorization. The environment
variable EDITOR determines which editor is invoked
with the -e option. The default editor is ed(1).
All crontab jobs should be submitted using crontab.
Do not add jobs by just editing the crontab file,
because cron is not aware of changes made this way.
If all lines in the crontab file are deleted, the
old crontab file is restored. The correct way to
delete all lines is to remove the crontab file
using the -r option.
If username is specified, the specified user's
crontab file is edited, rather than the current
user's crontab file. This can only be done by root
or by a user with the solaris.jobs.admin authoriza-
tion.
-l Lists the crontab file for the invoking user. Only
a user with the solaris.jobs.admin authorization
can specify a username following the -r or -l
options to remove or list the crontab file of the
specified user.
-r Removes a user's crontab from the crontab direc-
tory.
EXAMPLES
Example 1: Cleaning up Core Files
This example cleans up core files every weekday morning at
3:15 am:
SunOS 5.10 Last change: 10 Nov 2005 3
User Commands crontab(1)
15 3 * * 1-5 find $HOME -name core 2>/dev/null | xargs rm -f
Example 2: Mailing a Birthday Greeting
This example mails a birthday greeting:
0 12 14 2 * mailx john%Happy Birthday!%Time for lunch.
Example 3: Specifying Days of the Month and Week
This example runs a command on the first and fifteenth of
each month, as well as on every Monday:
0 0 1,15 * 1
To specify days by only one field, the other field should be
set to *. For example:
0 0 * * 1
would run a command only on Mondays.
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment
variables that affect the execution of crontab: LANG,
LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.
EDITOR Determine the editor to be invoked when the
-e option is specified. This is overriden by
the VISUAL environmental variable. The
default editor is ed(1).
VISUAL Determine the visual editor to be invoked
when the -e option is specified. If VISUAL
is not specified, then the environment vari-
able EDITOR is used. If that is not set, the
default is ed(1).
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
SunOS 5.10 Last change: 10 Nov 2005 4
User Commands crontab(1)
FILES
/etc/cron.d main cron directory
/etc/cron.d/cron.allow list of allowed users
/etc/default/cron contains cron default set-
tings
/etc/cron.d/cron.deny list of denied users
/var/cron/log accounting information
/var/spool/cron/crontabs spool area for crontab
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcsu |
|_____________________________|_____________________________|
| Interface Stability | Standard |
|_____________________________|_____________________________|
SEE ALSO
atq(1), atrm(1), auths(1), ed(1), sh(1), vi(1), cron(1M),
su(1M), auth_attr(4), attributes(5), environ(5), stan-
dards(5)
NOTES
If you inadvertently enter the crontab command with no argu-
ments, do not attempt to get out with Control-d. This
removes all entries in your crontab file. Instead, exit with
Control-c.
If an authorized user modifies another user's crontab file,
resulting behavior can be unpredictable. Instead, the
SunOS 5.10 Last change: 10 Nov 2005 5
User Commands crontab(1)
super-user should first use su(1M) to become super-user to
the other user's login before making any changes to the
crontab file.
When updating cron, check first for existing crontab entries
that can be scheduled close to the time of the update. Such
entries can be lost if the update process completes after
the scheduled event. This can happen because, when cron is
notified by crontab to update the internal view of a user's
crontab file, it first removes the user's existing internal
crontab and any internal scheduled events. Then it reads the
new crontab file and rebuilds the internal crontab and
events. This last step takes time, especially with a large
crontab file, and can complete after an existing crontab
entry is scheduled to run if it is scheduled too close to
the update. To be safe, start a new job at least 60 seconds
after the current date and time.
If an authorized user other than root modifies another
user's crontab file, the resulting behavior can be
unpredictable. Instead, the authorized user should first use
su(1M) to become super-user to the other user's login before
making any changes to the crontab file.
SunOS 5.10 Last change: 10 Nov 2005 6
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This page was generated on Wed Sep 12 11:24:32 GMT 2007
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