Cron is a job scheduler that allows users to run commands periodically.

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command for counting number of active cron jobs in crontabs

Problem statement I have 5 solaris boxes, some have Solaris 10 and some have Solaris 9. All of them have many cronjobs in their crontabs. I would like to know number of active cronjobs available, so ...
5
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3answers
1k views

Frustrating issue where neither cron nor su -c runs my job (permissions?)

Updated (and snipped) with more details below. I've set up a cron script and I'm trying to debug why it's not running. [Snipped context testing, which is all ok; see revision 2 for details] The ...
2
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2answers
422 views

changing default shell to /bin/bash of at job scheduler like in CRON

I recently switched from 2>&1 >> to &>> Is there a way to have at use /bin/bash as the shell? By default it uses /bin/sh and the man page gives no indication how anything else ...
2
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2answers
451 views

Is crontab related to server performance?

I am using Solaris 10, and I am adding many cronjobs to my server's crontab. Currently I have 30 cronjobs in my crontab. one cronjob takes 8 hours to complete ,one other cron job takes 5 hours to ...
13
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2answers
1k views

Origin of the word cron?

Trying to settle a friendly argument. Is "cron" an acronym for something? Additionally, did it's current canonical name "cron" originate from something shortened for something like chronos or ...
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2answers
2k views

Logging ALL stderr output of crontab to file

For example, I can log stderr of one script in this way: * * * * * run_script.sh > /var/log.txt 2>&1 But I want to log stderr of all scripts in my crontab. I can append > /var/log.txt ...
9
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2answers
2k views

Automatic security updates on Debian squeeze server

For a production Debian squeeze server, what are the best practices or recommendations for handling security updates? I have seen various articles on cron-apt, apticron, unattended-updates, apt cron ...
13
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1answer
3k views

How can I execute `date` inside of a cron tab job?

I want to create a log file for a cron script that has the current hour in the log file name. This is the command I tried to use: 0 * * * * echo hello >> ~/cron-logs/hourly/test`date "+%d"`.log ...
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2answers
2k views

List currently running cron tab and stop it

I created a cronjob, it runs for a very long time but now don't know how to stop it. Please help.
6
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1answer
2k views

Meaning of “* */1 * * *” cron entry?

Somehow, I am finding it difficult to understand tweaking around * parameters with cron. I wanted a job to run every hour and I used the below setting: * */1 * * * But it does not seem to do the ...
5
votes
1answer
1k views

Running cron script with lynx fails to work

I'm trying to automate a login process that can only be done through a browser. I am using the lynx browser to script the actions required to do this. Lynx does this by dumping a user's keystrokes ...
4
votes
2answers
961 views

cifs write errors in cron job

EDIT: THE SOLUTION With Tim's help I determined that larger writes of data were failing versus smaller ones. Why they didn't fail when I ran the script interactively, I don't know...But here was the ...
0
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2answers
1k views

Sending cron output to email?

I'm trying to send cron output to an email address and am struggling... I'm running the following command: 13 15 * * 1-5 root /path/to/mysql-backup.sh 2>&1 | mail -s "Daily Database Backup ...
1
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1answer
118 views

Can I filter how often cron emails me?

I have a few cronjobs and one of them is run every minute. I had to take a website down for two hours and it caused an error on that one specific cronjob and I got almost 120 emails in those two hours ...
4
votes
3answers
731 views

Crontab job not emailing on failure

I have a cron job on Debian: 1 * * * * /home/paradroid/bin/myscript.sh >/dev/null There is an installed and configured MTA, and I have received emails when the script has a syntax error, so I ...
2
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4answers
511 views

Is there any handy command line tool to manage Cron jobs?

Would someone suggest any handy command line (NOT web) tool or script which adds, enables and disables Cron jobs? I am looking, for example, for the following (or similar) behavior: sh manageCron.sh ...
4
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2answers
3k views

How can I know when a cron job was killed or it crashed?

Usually when a cron job crash, it will leave some error messages in the log. We run shell script and some java program with cron job. Recently we found some weird thing out from the log. Obviously ...
14
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6answers
22k views

How can I run a cron command with existing environmental variables?

How can I run a cron command with existing environmental variables? If I am at a shell prompt I can type echo $ORACLE_HOME and get a path. This is one of my environmental variables that gets set in ...
5
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2answers
4k views

Can I change the default mail recipient on cron jobs?

I believe that if there is any output from a cronjob it is mailed to the user who the job belongs to. I think you can also add something like MAILTO=vivek@nixcraft.in at the top of the cron file to ...
0
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1answer
524 views

grep searchstring /etc/crontab strange behavior in BASH script

I am working on a BASH script which creates automated backups via the crontab. I am trying to use myVARIABLE=`grep backup /etc/crontab` to return lines containing "backup" if an entry has already ...
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vote
2answers
1k views

Using rsync in a cronjob when a password is needed

Basically I have a bash script that fetches data from my server to perform a backup. As it is now I have to start that script manually, enter the password, and then wait for it to finish. I would ...
7
votes
1answer
2k views

List of modified files of the past 24 hours

Is there a reliable way to have a system that mails me the list of files that were modified in the past 24 hours inside a set of directories? (like /home/*/public_html/* and /home/*/*domains/*)
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1answer
68 views

App which can execute arbitrary code on different events

I've been looking for a simple activator which can execute some code when stuff happens, I haven't found anything yet. Maybe, I am not using the right keywords. It would be great if someone pointed me ...
6
votes
1answer
2k views

How do I enable locate and queue the database to be built?

On a new Ubuntu 10.4 instance, I tried to use the locate command only to receive the error locate: can not stat () `/var/lib/mlocate/mlocate.db': No such file or directory from using this command ...
14
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3answers
3k views

Are multiple @daily crontab entries processed in order, serially?

I want two jobs to run sometime every day, serially, in exactly the order I specify. Will this crontab reliably do what I want? @daily job1 @daily job2 I'm assuming they run one after the other, ...
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vote
2answers
383 views

Crontab not triggered

I have a program written in C with OpenCV. It captures an image from the webcam and saves on the disk with the name given as an argument. I want to trigger it every minute, thus I inserted the ...
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3answers
2k views

/etc/crontab what does “test -x” stand for

In my /etc/crontab file I have: # m h dom mon dow user command 17 * * * * root cd / && run-parts --report /etc/cron.hourly 25 6 * * * root test -x /usr/sbin/anacron || ( cd / ...
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2answers
2k views

How to access X display from a cron job when using gdm3? [duplicate]

Possible Duplicate: Open a window on a remote X display (why “Cannot open display”)? I'm trying to run a cron job that needs access to my X session. I know my X session will ...
5
votes
2answers
285 views

cron every X exact meaning

In cron you can specify */n where n means every n times period, for instance in the first column is minute. */5 means every 5 minutes, but which minutes? 0, 5, 10, ...? What happens if the number ...
3
votes
1answer
401 views

Using rsync + cron to sync a machine behind a firewall with my dropbox

I have a machine (A) behind a firewall with no access to the Internet, on this machine I can NFS mount directories on another machine (B) which can access internet, and is accessible from Internet, ...
0
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2answers
1k views

Running Python script via cron with sudo?

Im using Linux Mint. I have written a python script that is designed to not be accessible to the logged in standard user but is still be executed while they are logged in. It is to run and log them ...
2
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1answer
676 views

crontab “0/15” minutes + “11-15” hour field: when does that end?

Given a crontab expression like "0 0/15 11-15 ? * MON-FRI", how is that parsed? I am correct in assuming the 11-15 does not mean "between 11 and 15" but "when the hour is 11-15, inclusive" - i.e. ...
6
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5answers
4k views

Run script in a non interactive shell?

I have a cron job that is running a script. When I run the script via an interactive shell (ssh'ed to bash) it works fine. When the script runs by itself via cron it fails. My guess is that it is ...
1
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1answer
2k views

How to remove obsoleted logs with logrotate?

I wanted to remove unnecessary logs automatically , like Xorg.log.0 , and other packed *.gz files , i really don't need that on a laptop system. However , i checked man logrotate , but only an entry ...
26
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9answers
11k views

Correct locking in shell scripts?

Sometimes you have to make sure that only one instance of a shell script is running at the same time. For example a cron job which is executed via crond that does not provide locking on its own (e.g. ...
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1answer
307 views

vixie-cron.x86_64 doesn't seem to execute jobs on crontab

I have installed crontab on CentOS 5.6 x64 via yum install vixie-cron.x86_64 Here is my crontab -e SHELL=/bin/sh 0 0 * * * cat /root/mysql-backup.txt | xargs ...
6
votes
2answers
3k views

Can I automate tar's multi-volume-feature?

Ok, so I've just had a read through this page after a way to improve my current backup solution on my Debian server. Tar seems to be offering a quite nice multi-volume feature, although when I try it ...
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2answers
651 views

How to start the cron daemon

I am using RHEL 5.4 I killed the cron daemon accidentally. I wanted to stop a cron task, didn't know how to do it, ended up killing the cron daemon itself. How do I start it again?
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votes
3answers
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How do I add an entry to my crontab?

I am using crontab for the first time. Want to write a few very simple test cron tasks, and run them. $crontab * * * * * echo "Hi" doesn't produce anything. crontab */1 * * * * echo "hi" says ...
4
votes
2answers
2k views

How to run a cronjob in my regular environment?

Both the shell and environment variables that cronjobs are run in is completely different from the ones presented to me in gnome-terminal. How can I run a cronjob under the same circumstances as if I ...
2
votes
1answer
135 views

Need to find a cronjob

I have a problem, some user ,and I'm not sure who, on one of my servers wrote a cronjob that executes every night at midnight. The cronjob creates a sql dump of a database which is then grabbed by ...
0
votes
1answer
151 views

Is there a way to combine a file with crontab?

I'm trying to create an interface that will show a message on the screen every set time. Cron is an ideal tool for this case only it doesn't read data from a file during it's run (as far as I could ...
3
votes
3answers
1k views

How can I use cron to display messages on the screen via notify-send

I am toying around with notify-send and cron (on an Arch machine) and I can't figure out a way to combine them: I tried the solution given here and here, but neither worked. How can I use them? ...
3
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3answers
715 views

Is crontab multithread?

I don't know where I can find more information about crontab, so I ask here. Crontab is it multithread? How does it work?
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1answer
2k views

Cron job not executing

I'm trying to use cron for the first time, and I'm stuck. I'm using Ubuntu 10.10, and the following is my /etc/crontab file. The only modification that I've made is appending the last line. I've ...
3
votes
1answer
667 views

How to use cron + python to regularly adjust screen brightness?

I want to use cron and this script (http://askubuntu.com/questions/23593/use-webcam-to-sense-lighting-condition-and-adjust-screen-brightness): import opencv import opencv.highgui import time import ...
3
votes
1answer
493 views

Scheduled task on reboot

How can I schedule a task to run on next reboot? I understand that we have tools like cron and at to help with scheduling. But they seem to allow scheduling at a specific time and not on specific ...
0
votes
3answers
689 views

How to use gnome-session-save from cron?

I am trying to issue the gnome-session-save --kill command via crontab. I used the command sudo crontab -e. In the file is this: PATH=/usr/bin 00 00 * * * gnome-session-save --kill The command does ...
2
votes
1answer
258 views

Cron & Gnu Screen - Trouble with detached screen [duplicate]

Possible Duplicate: sending text input to a detached screen I have a script for my Minecraft server that runs automatically every 15 minutes. The problem is that after a server reboot, ...
5
votes
2answers
969 views

Open emacs in a terminal when editing crontab

I have setup emacs as my default editor in /etc/profile. When I want to use emacs in a terminal. I open it with the -nw option. How can I have the same behavior when doing a crontab -e preventing it ...