Questions tagged [cron]

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

16
votes
8answers
15k views

cron Vs. sleep - which is the better one in terms of efficient cpu/memory utilization?

The Case: I need to run some commands/script at certain intervals of time and for this I have two options: set up a cron-job implement a loop with sleep in the script itself. Question: Which is ...
11
votes
4answers
11k views

Is setting a higher nice level for a process an effective way to reduce its impact on system load/CPU time?

I have an rsync cron job which is pushing the server load and triggering monitor alerts. If I set the job to be run with a high nice level, would that effectively reduce the impact it has on system ...
11
votes
5answers
18k views

Not able to ssh in to remote machine using shell script in Crontab

Below is the script which i am trying to run, which runs without any issue for i in `seq 200 2100` do usr=(`ssh -t -t -o ConnectTimeout=60 machine$1 finger | tail -1 | awk '{print$1}'`) echo $...
9
votes
4answers
27k views

Installing crontab using bash script

I have created a script to install two scripts on to the crontab. #!/bin/bash sudo crontab -l > mycron #echo new cron into cron file echo "*/05 * * * * bash /mnt/md0/capture/delete_old_pcap....
3
votes
3answers
914 views

Automating tasks on a website on a headless server

I want to automate a task which can only be done on a website (with prior login) on my debian server. There is no public API available, so I can't use one. Is there a way to do so? I thought about a ...
13
votes
2answers
22k 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 ...
7
votes
5answers
6k 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? EDIT:...
6
votes
3answers
29k views

Using nohup to keep a script running indefinitely

I am very new to Linux and I've only been using it to SSH to my web server using Putty. The issue I am having is this: Basically I've got 2 php scripts. One get_tweets.php constantly listens for ...
2
votes
2answers
4k views

Pimp rsyslogd to have less i/o (cron, pam,…) and less logging

On my raspberry I really don't need crons and pam logging and I want to have less i/o to make the SD card life a little longer.. I have already removed cron with the second line cron.none, I'm ...
2
votes
3answers
4k views

Not all shell scripts working with crontab

I have a little VPS I run apache and a Minecraft server on. I don't ever turn it off, but should I restart it for some reason, IPTables blocks most of my ports, including port 80. I've tried so many ...
2
votes
1answer
1k views

Check for process already running in webfaction?

I use Django framework on webfaction and have 5 different cron jobs. One of them lasts much longer than others and sometimes gets stuck (30-120 seconds or more). I have already set that cron job to ...
1
vote
2answers
10k views

sh script will not execute as root (cron)

I have the following script added to cron. If I add touch thisisatest.file to the first line it will create a file named thisisatest.file, but not execute the rest of the code. If I manually type ./...
0
votes
1answer
372 views

How would you edit `/etc/crontab` and files under `/etc/cron.d/?

In my /etc/crontab # /etc/crontab: system-wide crontab # Unlike any other crontab you don't have to run the `crontab' # command to install the new version when you edit this file # and files in /etc/...
-1
votes
5answers
4k views

Use a password in shell-script

I want to create a cron script to interact with mysql, for example #!/bin/bash mysql -uroot -p echo root echo "CREATE DATABASE example" But it doesn't work, it only prompts: Enter password: and ...
6
votes
3answers
3k views

Shebang does not set SHELL in cron

I have a script containing: #!/bin/bash printenv When I run it from the command line: env testscript.sh bash testscript.sh sh testscript.sh every time, it outputs SHELL=/bin/bash. However, when it ...
5
votes
3answers
3k views

Who starts unattended-upgrades?

I'm wondering who starts unattended-upgrades in my debian-jessie: my man page DESCRIPTION This program can download and install security upgrades automatically and unattended,...
5
votes
2answers
377 views

Upgrading packages automatically

I'm am 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? sudo apt-get ...
4
votes
1answer
2k views

sudo source: command not found

I want to run this program as root. It activates a virtual environment and runs a python program in that virtual environment. The program looks like this $cat myfile.sh source /pathto/venv/bin/...
3
votes
1answer
3k 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: ...
3
votes
1answer
5k views

Cron does not print to syslog

I have following crontab file - # /etc/crontab: system-wide crontab # Unlike any other crontab you don't have to run the `crontab' # command to install the new version when you edit this file # and ...
2
votes
3answers
459 views

Cron job doesn't run once per week

We have a job that is set to run Monday thru Friday. Up until two weeks ago, it ran fine 5 days a week. For the last two weeks it has failed on Monday. I am unable to locate where to find the point of ...
2
votes
3answers
19k views

Watchdog script to keep an application running

I currently use an application called MxEasy on my linux servers to display video from a couple of IP cameras. The software is rather buggy and crashes occasionally. I've wrote a script that checks to ...
1
vote
1answer
55 views

Are cron tasks in `/etc/cron.d/` files supposed to not contain `sudo`?

In /etc/cron.d/myjob, I create a cron task of running a bash script and redirect its stdout and stderr to a log file. The script contains a line of sudo running a command. In the log file: sudo: no ...
1
vote
1answer
640 views

Environment variables are not passed to sub scripts while running on crontab

I was trying to run one of the scripts (for example, wrapper.sh) which internally executes other scripts using crontab. It works fine without any issues. When I have created a environment file (which ...
1
vote
2answers
694 views

Whose PATH value is the default PATH value in a crontab file? [duplicate]

root's default PATH is $ sudo su # echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games After creating /etc/cron.d/myjob 35 * * * * tim ( date &&...
1
vote
4answers
22k views

Cronjob doesn't execute shell script, but when I am executing it standalone it works. Why?

Shell Type: >echo $SHELL /bin/ksh Cronjob : 15 * * * * /bin/ksh /wls_domains/resMGT/logs/bea/wlr3queuetransaction.sh > /wls_domains/resMGT/logs/bea/data/script.log The script is as below: #...
0
votes
2answers
4k views

Ubuntu crontab php not working

Yes, I have read many, many documentations but I can't get it to work. I have a simple single php file which I want to run once or twice in a minute. My php file is called: cronjob_refresh.php and I'm ...
0
votes
5answers
2k views

cron job schedule

I created a cron job using * */2 * * * schedule. Can anyone tell me what schedule this refers to? I guess it should execute every 2 hours, but it seems to execute every minute.
0
votes
1answer
129 views

Password change Script

i am having a file, which contains usernames and encrypted passwords (openssl passwd) in the format user:password. Now i want to change the password of this User with a Cronjob once a week. With the ...
26
votes
10answers
82k views

How to restart the Python script automatically if it is killed or dies

I am running my Python script in the background in my Ubuntu machine (12.04) like this - nohup python testing.py > test.out & Now, it might be possible that at some stage my above Python ...
20
votes
5answers
148k views

How do I create a service for a shell script so I can start and stop it like a daemon?

I'm using CentOS 7 what my aim is to create a cron for every five seconds but as I researched we can use cron only for a minute so what I am doing now is I have created a shell file. hit.sh while ...
36
votes
3answers
112k views

As root, how can I list the crontabs for all users?

I have a script being run automatically that I can't find in the crontab for the expected users, so I'd like to search all users' crontabs for it. Essentially I want to run a crontab -l for all users....
28
votes
8answers
92k views

Why did my crontab not trigger?

I used crontab -e to add the following line to my crontab: * * * * * echo hi >> /home/myusername/test Yet, I don't see that the test file is written to. Is this a permission problem, or is ...
17
votes
6answers
18k 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 ...
31
votes
1answer
130k views

Where to find the Crontab logs in CentOS

First of all I'm using CentOS [root@a etc]# cat system-release CentOS release 6.5 (Final) [root@a cron.daily]# ps -ef | grep cron root 982 1 0 Jun14 ? 00:01:15 crond root ...
19
votes
3answers
20k views

Crontab entry with hour range going over midnight

Is this valid crontab time specification, doing what is expected: 0 22-4 * * * Or is it necessary to do something like 0 22,23,0,1,2,3,4 * * *
17
votes
1answer
4k 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 ...
15
votes
4answers
52k views

mail: cannot send message: process exited with a non-zero status

I've had a cronjob working for about a fortnight without any problems. Then last night I checked I didn't get the email that I usually get. I went to the terminal to try send myself an email, I got ...
7
votes
2answers
9k 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 ...
14
votes
5answers
147k views

crontab -e , then 0 * * * * = every hour… Where is stored

After sudo crontab -e (it wrote "/tmp/crontab.XXXX70pN9h" 1L, 19C 1,1 All Then I saved the file. And to check..? (how? i don't know) And to check I ps -e | grep cron 29818 ? ...
11
votes
3answers
10k 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 2&...
11
votes
2answers
2k views

systemd - Timer units that mimic anacron behaviour

I need to write a timer unit for a machine which is turned of frequently (e.g. classical desktop setup). This timer unit needs to be activated regularly but not very often (e.g. weekly, monthly). I ...
10
votes
2answers
24k views

How come crontab -e is different from less /etc/crontab?

Im pretty new to unix and crons, I was currently about to try to add crons to an existing cron file. I read you could do this with crontab -e. The confusing thing to me is just that crontab -e shows ...
7
votes
3answers
16k views

Shall I save my crontab file in /tmp?

I ssh to a server, and want to add some daily jobs (specifially to renew Kerberos tickets even when I log out and I still want my programs in screen or tmux continue to run) to cron. So I run crontab -...
7
votes
2answers
11k 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 ...
7
votes
1answer
12k views

Automatically detect when a file has reached a size limit

I would like to send an email when a file reach a certain size limit. The only way I thought of doing this is by doing a cronjob which will check the file size and send the email if the file is ...
4
votes
3answers
15k 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 ...
3
votes
4answers
11k views

Running `screen` through a @reboot cron job

I want to have a script running in screen at startup. This doesn't work: @reboot pi screen -d -m /home/pi/db_update.py however running this manually as user pi works: screen -d -m /home/pi/...
-2
votes
2answers
707 views

CRON job that run every 130 seconds

Is it possible to create a CRON job that can run every 130 secs or 2 min and 10 secs.
18
votes
2answers
4k views

Suppress output unless non-zero exit code

What's the best way to suppress output (stdout and stderr) unless the program exits with a non-zero code? I'm thinking: quiet_success() { file=$(mktemp) if ! "$@" > "$file" 2>&1; then ...