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

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How is this crontab interpreted “*/N * * * *” where N is between 31 and 59?

If I need to run jobs exactly every 50 minutes, example. 00:50 run 1 01:40 run 2 02:30 run 3 03:20 run 4 04:10 run 5 05:00 run 6 06:50 run 7 Will */50 * * * * cron work as expected?
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255 views

Difference between CRON tab 0/5 and */5?

The title says it all is there any difference between creating a CRON tab using 0/5 and */5? For example: 0/5 * * * * vs */5 * * * *
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207 views

Cron not working at startup, but works if restarted?

For some testing, I need to reboot my system every minute. I have a busybox based system, installed cron using opkg. I setup a cron job using crontab, everything looks ok: root@SL1000-1103DC:~# ...
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52 views

Send email on every change of service status

I am running a Debian server and i have setup mailutils to send an email from command line from root@localhost to an external email. I would like to slightly modify it, so it can send emails on every ...
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1answer
169 views

Loading crontab from file at startup

I'm starting machines from an AMI (Amazon Machine Image) on AWS (Amazon Web Services) and want to load the crontab dynamically from a file instead of using the AMI's crontab. One approach I thought ...
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2answers
164 views

about executing a python program in a shell script which is scheduled on crontab

i have a problem with regards on crontab. I have a script named checker.sh and i want to schedule it that would run every minute: * * * * * sh /home/pi/checker.sh so i have the script here: the ...
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3k views

How to activate Virtualenv when a Python script starts?

I want to schedule a python script to run using cron on certain dates, the problem is that in order for example.py to work, example-env has to be activated, is there a way to make example.py activate ...
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2k views

nginx logrotate error on cron job

I'm running Ubuntu 14.04 LTS and nginx on a Digital Ocean VPS and occasionally receive these emails about a failed cron job: Subject Cron test -x /usr/sbin/anacron || ( cd / && run-parts ...
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807 views

Regex for crontab validation

I need to check in bash whether an entry into the crontab file is valid. Is there a crontab command switch? I can extract individual lines and try to control individual items through regex. But I ...
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3answers
295 views

Cron job not saving

I'm trying to write a very basic cron job but it doesn't seem to be saving. Here's what I've done: 1) crontab -e This opens up a file with vim. 2) #!usr/bin/env python 0 23 * * 0 ~/Desktop/...
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935 views

tput: No value for $TERM and no -T specified

I am trying to run a bash script I have via cron, and I am getting the following error at the beginning of the execution: tput: No value for $TERM and no -T specified Here is what is in my crontab: ...
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140 views

Adding a crontab - syntax

crontab -l | { cat; echo "0 0 * * * /path/to/cron/job"; } | crontab - I took this line from the net, to add a new cron job. It works well and good. I got the doubts, 1) Why do we need the curly ...
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115 views

How to redirect tarsnapper output to /dev/null?

I use tarsnapper's make command for managing tarsnap backups like this: tarsnapper -c /usr/local/etc/tarsnapper.conf make Which works like it should and I get an output like this Creating backup ...
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1answer
421 views

How to schedule shutdown every day?

We have a server that is used for Linux thin clients in a class. The server is started when required and I want to schedule it to power off at 22:00 every day to avoid power wasting. I thought of ...
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1answer
375 views

Creating a cron job and watching its output in real time

When I look at the questions and answers on this forum, it seems like the threshold to ask a question is very high. At least for someone like me, with very little knowledge of Linux. Most of the ...
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1answer
102 views

what is the difference between cron and systemd ?

what is the difference between cron and systemd ? Why we can't use use only one of this two?
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2answers
773 views

How to set up cron job in Linux to delete all regular files?

I need to set up a job to delete all of the regular files in the /home/admin directory on the second day of every month at 8:30 A.M. It seems like wrong command: # crontab -e 30 08 02 * /bin/find /...
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2answers
321 views

CRON Job To Execute Command On Low Memory

I have a situation where I may need to execute an SAP command line tool hdbsql when memory gets too low (to help clean out the HANA table cache). I'm not well versed in Unix/Linux, and was wondering ...
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1answer
390 views

Task not run by crontab

crontab strangely does not execute my script, although the script is running just fine from the shell terminal. I already made sure that scripts are separated from each other by a new line space. ...
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358 views

Running a ruby cron job

I was trying to create a cron job which runs a ruby code on digital ocean, however it seems I'm making a mistake. It doesn't give any error but it doesn't also do anything. I ran this cronjob on my ...
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3answers
785 views

how to tell crontab to execute the command from now instantly

I have a command in "/etc/crontab" which runs a database program every 7 days. Now, I see that this command has been commented by another user for 2 weeks. I immediately uncommented the line, and ...
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4answers
465 views

Only allow process to run between hours x and y

I use a mobile data connection service. I only have unrestricted bandwidth between 9am and 4pm. I wonder how I can "silence" applications such as the Dropbox applet outside that schedule. I thought ...
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2answers
4k views

Run A Cron Job Task Every 30 Seconds [duplicate]

It's possible to set the cron job tool in my website cpanel 'VPS Hosting' to execute php file every 30 second I am using it to execute php file once at a minute *,*,*,*,* but I need to set it to run ...
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1answer
81 views

Checking the schedule of a cronjob and doing a conditional check on specific parts

Edit: I managed to solve this myself, I actually deleted my original question as I was over complicating the process slightly, but have since answered it in case others find it useful. RegExp is not ...
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1answer
204 views

help with remote file find/scp

I have a set of files on a remote sftp which I need to download to a server every day. sftp uses ssh keys to authenticate, so I created a ssh key and added to the remote server authorized folder. I'm ...
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266 views

Cron Job every 55 minutes [duplicate]

I want cron to be run in every 55 mins. I followed the link CronJob every 25 minutes and my crontab command is */5 * * * * [ $(( $(date +%s) / 60 % 55 )) -eq 0 ] && wget http://localhost/...
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410 views

Issue Using Crontab to Create/Restart Screen and Run Command

I want to have a certain script (rails rake task) running on my server at all times - it basically populates my DB using a live feed. I can create a screen (http://linux.die.net/man/1/screen) and run ...
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4answers
1k views

How to stop minute cron job?

I have a program written in python; my program scrapes a value from some financial website every minute and pushes that value into my DB. My program takes like 1 or maximum 1.5 seconds to do this job....
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3answers
820 views

Cron job to run every minute from 11PM to 6AM

I have a python program which I need to run every minute from 11PM (EDT) to 06AM (EDT). How can I schedule a cron job to do this? * 23-6 * * 1-5 python my_program.py will this work? or do I have to ...
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142 views

How can I make `sudo crontab -e` use my `sudoedit` environment?

I've started using sudoedit <file> instead of sudo vim <file>. One of the advantages is that it uses my local ~/.vimrc. However, when using sudo crontab -e, it uses /root/.vimrc instead. ...
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132 views

how to prevent cron job email splitting into multiple lines

CRON has emailed me the extract below : May 12 04:27:54 rpi postfix/smtpd[9343]: NOQUEUE: reject: RCPT from unknown[95.211.213.214]: 504 5.5.2 <WIN-HBAL58UG0JH>: Helo command rejected: need ...
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374 views

Skip syslog/rsyslog logging of certain cron jobs

In most GNU/Linux distributions the default is to log start (and many different events) of every cron job to syslog. It's rather convenient, but not for a very frequent jobs, which started, say, every ...
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354 views

Cron job which runs every 5 seconds

I need to create an cron job with the following functionality: The job should go to a particular directory and touch one file every 5 seconds. It should run for only 1 minute. The logic is to ...
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1answer
221 views

Does systemd timer unit skip the next run if the process hasn't finished yet?

I want to use systemd to run a command every 5 minutes. However, there is a risk that occasionally the task may take longer than 5 minutes to run. At that point, will systemd start a second instance ...
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1answer
100 views

A generic cron wrapper that records all output

I am hoping to write a cron wrapper that records all output in a folder $CRON_LOG_DIR. It would be used as, e.g., follows: * * * * * $CRON_WRAPPER "<job name>" "command" which would record ...
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3answers
361 views

Cron job working, but crontab -l says no jobs

I am running Raspbian on a Pi and installed cron to schedule a job. I wrote a Python script and I set it to run every 5 minutes. The job is happening every 5 minutes, no problems, but when I run ...
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104 views

problem with cron job for every 2 minutes

I have a cron job for very 2 min and somebody told me that some servers do not allow 2 min cron jobs. basically from 30 min. it is true?
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303 views

Upgrading packages automatically

I'm fairly new to using servers (debian 7) and I'm currently running cron-apt to e-mail me when there are new upgrades available. Is the following command safe to run when new upgrades are shown? ...
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186 views

How to overcome this error when running a script in crontab?

This is basically my script. #!/bin/sh #set -x PATH=/usr/jdk/instances/current/bin:/usr/bin:/bin:/opt/ss7/access/bin:/opt/ss7/sgc/bin:/opt/ss7/access/install:/opt/ss7/sgc/install:/usr/jdk/instances/...
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1answer
193 views

Usage of '%' in the crontab [duplicate]

I am trying to add a cron job to perform an rsync from a remote server to a (Ubuntu12) local machine & create a log file. Below is the crontab-l 00 18 * * * rsync -a -v --delete -e ssh user@...
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91 views

Crontab giving no result

I have set up a cronjob on my server which is supposed to run every minute and store the output in the given file. I have been trying a lot and saw a lot of links but nothing seems to work. Following ...
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2answers
93 views

how to get the run results of the cron job

I wrote a simple Hello World Java Program and created a jar file of it. Now to test the cron job, wrote a crontab.txt file with the line 50 12 27 4 1 java -jar HelloWorld.jar and saved it. At the ...
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0answers
40 views

How do I process new additions to logs

I know that I can use a few tools like tail and less to view the newest additions to a growing log file. What I want to do, though, is run some sort of script at regular intervals (like cron) on the ...
2
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1answer
302 views

Script not run with cron [closed]

i have a python script when i launch my script all it's ok but when i lauchn my scrypt under crontab i have this errors: .. 2015-04-24 14:36:02,163 ERROR Problème dans le module importData[...
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2answers
106 views

Cron job is writing the error to error log but fails to write outputs to output log file

I have 2 python codes which i schedule using cron. My codes actually runs from 10:30am to 4:20pm everyday. from 10:30am to 11:00am my codes outputs 2-3 lines every minute and after that they start ...
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1answer
137 views

What could be happening between pidof and kill to cause “no such process”?

I've inherited quite a bit of code and am looking at a cron job that restarts a service once an hour, no other scripts touch this process and this code is ran. #The name of the process has been ...
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1answer
1k views

Default umask for cron jobs

How to set default umask for cron jobs, please? (On RHEL 6.) Jobs are started under non-interactive (obviously) no-login (?) shell. Not only I prefer dash over bash. But consider also bash called as /...
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176 views

Schedule backup with notification?

To avoid editing files at the same time of backup scheduled by cron, I figure out a way: Before backup, send a desktop notification such as notify-send -t 0 "Ready for backup", to let me prepare (...
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3answers
265 views

My cron job doesn't run

I set up to run notify-send every minute, $ crontab -l 1 * * * * /usr/bin/notify-send -t 0 "hello" Why does it not work? Do I need to restart OS after editing the crontab file? Does the following ...
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1answer
375 views

Why cron jobs' output keeps getting written to ~/dead.letter?

I have a job scheduled by cron running every day, and the job is about compressing a folder using tar; and I found that the standard output of tar keeps getting written into ~/dead.letter everyday. ...