at is usually for non-regular, one-time-only jobs while cron is usually for regular, perpetual jobs ...
at samples:
Code:
# harass the console user at 7:05 pm
at 1905
echo "This is my console!" > /dev/console
# reboot the box 1 hour from now
at now + 1 hour
sync; sync; reboot
cron samples:
Code:
# reboot host every weekday @ 8:30 pm
30 20 * * 0-5 (sync; sync; init 6) > /dev/null 2>&1
# annoy the console user every weekday @ 8:00 am
00 08 * * 0-5 echo "This is my concole!" > /dev/console
however, you can also get a job to go regularly with an at command by adding something like this in your script ...
Code:
at now + 1 week << GO
/path/to/this/script > /dev/null 2>&1
GO
... and a "one-time" job in cron ... (will only run when all time conditions are met) ...
Code:
# run the job at 1:01 am Monday, January 1
01 01 01 01 1 echo "This is my console!" > /dev/console
btw, it would be best if you get into checking the man pages while you're just starting ... see "man at" and "man crontab" ...
Hi all,
I dont know if its the right place to ask it,
but can someone please explaine me the differnce between sun 220R server to a sun netra 1125?
any recommendation on which one is better?
Dori (2 Replies)
Hi all,
I would like to know the difference between these commands
/usr/lib/fs/hsfs/mount -F /dev/lofi/1 /usr
and
mount -F hsfs /dev/lofi/1 /usr
In the first case absolute path is specified and in the next the cmd with options ,whats the differnce.
PS:am sorry ,coz this had been... (1 Reply)
Dear all
We have SunOS 5.10 Generic_127127-11 sun4u sparc SUNW,Sun-Fire-V250
i have scheduled cronjob but its not working
Crontab details
15 15 * * * /d5/oratest/testdb/hotbackup_new.sh TEST247
15 15 * * * mkdir -p rajesh /d4/appltest
Crontab log details
> CMD: mkdir... (4 Replies)
Greetings everybody,
I have an IBM P520 AIX 5.3 server machine and trying to use crontab to periodically excute a script that contains a command belongs to my software (Fast/Tools SCADA software)
I added the following line after using crontab -e
01 * * * * /mypath/myscript
I have two... (3 Replies)
Hi,
I had setup crontab to execute my script every day midnight 00:00
Below are the current settings.
crontab -l
0 0 * * * /apps/bin/compress.ksh_moht > /dev/null 2>&1
Should it not work?
I need help fix this? (8 Replies)
I can run manually script of ntopdump.sh but crontab can't run this script very five minutes.
# crontab -l
*/3 * * * * root sh /root/ping.sh
*/5 * * * * root sh /root/ntopdump.sh
#
# pwd
/root
# ls -l
total 88
-rwxrwxr-x 1 root root 1645 Jun 14 19:01 anaconda-ks.cfg
drwxrwxr-x 2 root... (14 Replies)
Shell = ksh
Hi all,
I scheduled an automated job on my application server like below,
30 13 * * 1-5 $HOME/my_script.sh
However the script was not executed as expected. Any reason that may cause this to happen? (6 Replies)
Hi,
When I set the crontab to run every minute, every hour, it works fine.
* * * * * env > /tmp/env.output
However I want to run it every day at 8:00 AM and it does not run.
* 8 * * * env > /tmp/env.output
I ran the 'date' command which says it's 8AM PST and also the 'TZ'... (0 Replies)
Hi,
I know this is a common topic. I'm trying to launch a perl script using a contab -e entry. I've been trying diff options but nothing seems to work:
My cron is running:
UID PID PPID C STIME TTY TIME CMD
root 3755 1 0 Nov27 ? 00:00:00 crond
This... (4 Replies)
Dear Friends,
I have Red Hat Linux Enterprise version 6.3. running SAP and oracle.
I have created one crontab for user orasid to execute one job periodically.
But it is not executing. I have checked crontab service is running.
Please help in the matter.
Regards,
Bhagawati Pandey (5 Replies)
Discussion started by: BPANDEY
5 Replies
LEARN ABOUT CENTOS
crontab
CRONTAB(1) User Commands CRONTAB(1)NAME
crontab - maintains crontab files for individual users
SYNOPSIS
crontab [-u user] file
crontab [-u user] [-l | -r | -e] [-i] [-s]
crontab -n [ hostname ]
crontab -c
DESCRIPTION
Crontab is the program used to install, remove or list the tables used to serve the cron(8) daemon. Each user can have their own crontab,
and though these are files in /var/spool/, they are not intended to be edited directly. For SELinux in MLS mode, you can define more
crontabs for each range. For more information, see selinux(8).
In this version of Cron it is possible to use a network-mounted shared /var/spool/cron across a cluster of hosts and specify that only one
of the hosts should run the crontab jobs in the particular directory at any one time. You may also use crontab(1) from any of these hosts
to edit the same shared set of crontab files, and to set and query which host should run the crontab jobs.
Running cron jobs can be allowed or disallowed for different users. For this purpose, use the cron.allow and cron.deny files. If the
cron.allow file exists, a user must be listed in it to be allowed to use cron If the cron.allow file does not exist but the cron.deny file
does exist, then a user must not be listed in the cron.deny file in order to use cron. If neither of these files exists, only the super
user is allowed to use cron. Another way to restrict access to cron is to use PAM authentication in /etc/security/access.conf to set up
users, which are allowed or disallowed to use crontab or modify system cron jobs in the /etc/cron.d/ directory.
The temporary directory can be set in an environment variable. If it is not set by the user, the /tmp directory is used.
OPTIONS -u Appends the name of the user whose crontab is to be modified. If this option is not used, crontab examines "your" crontab, i.e.,
the crontab of the person executing the command. Note that su(8) may confuse crontab, thus, when executing commands under su(8) you
should always use the -u option. If no crontab exists for a particular user, it is created for him the first time the crontab -u
command is used under his username.
-l Displays the current crontab on standard output.
-r Removes the current crontab.
-e Edits 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.
-i This option modifies the -r option to prompt the user for a 'y/Y' response before actually removing the crontab.
-s Appends the current SELinux security context string as an MLS_LEVEL setting to the crontab file before editing / replacement occurs
- see the documentation of MLS_LEVEL in crontab(5).
-n This option is relevant only if cron(8) was started with the -c option, to enable clustering support. It is used to set the host in
the cluster which should run the jobs specified in the crontab files in the /var/spool/cron directory. If a hostname is supplied,
the host whose hostname returned by gethostname(2) matches the supplied hostname, will be selected to run the selected cron jobs
subsequently. If there is no host in the cluster matching the supplied hostname, or you explicitly specify an empty hostname, then
the selected jobs will not be run at all. If the hostname is omitted, the name of the local host returned by gethostname(2) is
used. Using this option has no effect on the /etc/crontab file and the files in the /etc/cron.d directory, which are always run,
and considered host-specific. For more information on clustering support, see cron(8).
-c This option is only relevant if cron(8) was started with the -c option, to enable clustering support. It is used to query which
host in the cluster is currently set to run the jobs specified in the crontab files in the directory /var/spool/cron , as set using
the -n option.
SEE ALSO crontab(5), cron(8)FILES
/etc/cron.allow
/etc/cron.deny
STANDARDS
The crontab command conforms to IEEE Std1003.2-1992 (``POSIX''). This new command syntax differs from previous versions of Vixie Cron, as
well as from the classic SVR3 syntax.
DIAGNOSTICS
An informative usage message appears if you run a crontab with a faulty command defined in it.
AUTHOR
Paul Vixie <vixie@isc.org>
Colin Dean <colin@colin-dean.org>
cronie 2012-11-22 CRONTAB(1)