Cronjobs and Environmental Variables - cron

I have 2 versions of a site: Production and Dev. The file system is:
/public_html
production files.php
more_production_files.php
/dev
dev_file.php
etc...
Im setting up cron jobs, and I have environmental variables in the crontab to keep the paths correct for some of the PHP require() functions that are happening.
My question is, if I wanted to set up separate Dev and Production variables in the contab, can I do something like this?:
CRONTAB
# Dev Variables
ENVIRONMENT=/dev/
FULL_PATH=/home/username/public_html/dev/
# Dev Cron Jobs
0 0 1 1 1 php /home/username/public_html/dev/cronjob.php
0 0 1 2 2 php /home/username/public_html/dev/cronjob_2.php
# Production Variables
ENVIRONMENT=/
FULL_PATH=/home/username/public_html/
# Production Cron Jobs
0 0 1 1 1 php /home/username/public_html/cronjob.php
0 0 1 2 2 php /home/username/public_html/cronjob_2.php
When executing a Production cron job, would the 'Production Variables' above, replace the Dev ones? Similarly, when executing a Dev cron job, would the 'Dev Variables' be used as opposed to the Production ones?

As you seem to be running Linux, yes this works on most (at least recent) Linux distributions. For example, from the Ubuntu crontab(5) manual;
An active line in a crontab will be either an environment setting or a cron command. The crontab file is parsed from top to bottom, so any environment settings will affect only the cron commands below them in the file.

Related

Crontab not launching script

I'm trying to run the following script through crontab every day at 12 :
#!/bin/sh
mount -t nfs 10.1.25.7:gadal /mnt/NAS_DFG
echo >> ~/Documents/Crontab_logs/logs.txt
date >> ~/Documents/Crontab_logs/logs.txt
rsync -ar /home /mnt/NAS_DFG/ >> ~/Documents/Crontab_logs/logs.txt 2>&1
unmout /mnt/NAS_DFG
As it needs to run in sudo, I added the following line to 'sudo crontab' such that I have :
someone#something:~$ sudo crontab -l
# Edit this file to introduce tasks to be run by cron.
#
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
#
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').#
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
#
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
#
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
#
# For more information see the manual pages of crontab(5) and cron(8)
#
# m h dom mon dow command
0 12 * * * ~/Documents/Crontab_logs/Making_save.sh
But it does not run. I mention that just executing the script thourgh :
sudo ~/Documents/Crontab_logs/Making_save.sh
works well, except that no output of the rsync command is written in the log file.
Any ideas what's going wrong ? I think I checked the main source of mistakes, i.e. using shell, leaving an empty line at the end, etc ...
sudo crontab creates a job which runs out of the crontab of root (if you manage to configure it correctly; the syntax in root crontabs is different). When cron runs the job, $HOME (and ~ if you use a shell or scripting language with tilde expansion) will refer to the home of root etc.
You should probably simply add
0 12 * * * sudo ./Documents/Crontab_logs/Making_save.sh
to your own crontab instead.
Notice that crontab does not have tilde expansion at all (but we can rely on the fact that cron will always run out of your home directory).
... Though this will still have issues, because if the script runs under sudo and it creates new files, those files will be owned by root, and cannot be changed by your regular user account. A better solution still is to only run the actual mount and umount commands with sudo, and minimize the amount of code which runs on the privileged account, i.e. remove the sudo from your crontab and instead add it within the script to the individual commands which require it.

Cron job not running automatically for a non-root user

I am running SUSE Linux as a non-root user (getting root access also will not be a possibility). I would like to have a .sh script I created be run daily.
My crontab looks like:
0 0 * * * * /path/to/file.sh
I also have a line return after this as per many troubleshooting suggestions. My script deletes files older than 14 days. I also added a means to log output to check whether the script runs.
However, the job does not run automatically. I also am not able to check /var/log/messages for any notifications on whether cron can run or not.
What am I doing wrong? How can I check if cron itself is running/can run for my user? Do I have to supply cron with any paths or environment variables?
The correct approach to run your cron every midnight is:
00 00 * * * /bin/bash path/to/your/script.sh >> /path/to/log/file.log

running a script in crontab

I have a very simple script in my crontab that I want to run every day. It is located in /home:
-rwxr-xr-x 1 root root 40 Apr 15 08:01 kill_slony_stop_sql.sh
It has execute permission and here is the content:
#!/bin/bash
slon_kill;rcpostgresql stop
and here is the cron line for it to run daily:
56 12 * * * /home/kill_slony_stop_sql.sh
But it is not working for some reason. When I type /home/kill_slony_stop_sql.sh in the command line, it works good but it is not working in the crontab.
Any thoughts?
It is most likely a PATH issue. Have a look at Why is my crontab not running and be sure to set a PATH so that it can call your slon_kill command.
Also, add some debug to your cron
56 12 * * * /home/kill_slony_stop_sql.sh &>/tmp/errorcron.log
And also look at the logs; cron logs its actions via syslog, which (depending on your setup) often go to /var/log/cron or /var/log/syslog.
I had the same problem with a daily cron job, I used the #daily but this will run at 00:00 every day.
#daily /usr/local/bin/msa70_check.sh
was the cron tab line i added, below is the script i run.
#!/bin/bash
# msa70 disk check
/sbin/mdadm --detail /dev/md0 /dev/md1|
/bin/mailx -s"Disk check on server123 please check" person#domain.com
I also had to edit my script and add /sbin/ and /bin in front of mdadm and mailx for the cron job to run

Linux cronjob doesn't work (execute script)

I created a cronjob with the command crontab -e:
*/1 * * * * /var/lib/tomcat/webapps/ROOT/WEB-INF/scripts/test.sh
This file test.sh should be executed every minute. But it doesn't work.
If I run the script manually it works fine. So I think the problem is the cronjob not the script ;)
Are there any permissions or something else which block the cronjob?
Is the cronjob syntax correct?
Thx
For a start, you don't need the /1 if you want it done every minute. Just setting the minute field to * will do.
Next, you should place, as the first lines in your test script (though after the #! line if it's there):
env >/tmp/test.sh.dummy
set >>/tmp/test.sh.dummy
and see if that file shows up.
That will tell you if the script is running or not.
If it's not running, check to make sure cron itself is running:
pax> ps -ef | grep cron | grep -v grep
root 1048 1 0 08:45 ? 00:00:00 cron
(mine is).
If it is running, the most likely problem is that the environment under which cron runs your jobs is nowhere near the environment your shell gives you. Examine the differences between what was output to your /tmp/test.sh.dummy file and what your shell gives your when you execute env ; set.

Shell script to log server checks runs manually, but not from cron

I'm using a basic shell script to log the results of top, netstat, ps and free every minute.
This is the script:
/scripts/logtop:
TERM=vt100
export TERM
time=$(date)
min=${time:14:2}
top -b -n 1 > /var/log/systemCheckLogs/$min
netstat -an >> /var/log/systemCheckLogs/$min
ps aux >> /var/log/systemCheckLogs/$min
free >> /var/log/systemCheckLogs/$min
echo "Message Content: $min" | mail -s "Ran System Check script" email#domain.com
exit 0
When I run this script directly it works fine. It creates the files and puts them in /var/log/systemCheckLogs/ and then sends me an email.
I can't, however, get it to work when trying to get cron to do it every minute.
I tried putting it in /var/spool/cron/root like so:
* * * * * /scripts/logtop > /dev/null 2>&1
and it never executes
I also tried putting it in /var/spool/cron/myservername and also like so:
* * * * * /scripts/logtop > /dev/null 2>&1
it'll run every minute, but nothing gets created in systemCheckLogs.
Is there a reason it works when I run it but not when cron runs it?
Also, here's what the permissions look like:
-rwxrwxrwx 1 root root 326 Jul 21 01:53 logtop
drwxr-xr-x 2 root root 4096 Jul 21 01:51 systemCheckLogs
Normally crontabs are kept in "/var/spool/cron/crontabs/". Also, normally, you update it with the crontab command as this HUPs crond after you're done and it'll make sure the file gets in the correct place.
Are you using the crontab command to create the cron entry? crontab to import a file directly. crontab -e to edit the current crontab with $EDITOR.
All jobs run by cron need the interpreter listed at the top, so cron knows how to run them.
I can't tell if you just omitted that line or if it is not in your script.
For example,
#!/bin/bash
echo "Test cron jon"
When running from /var/spool/cron/root, it may be failing because cron is not configured to run for root. On linux, root cron jobs are typically run from /etc/crontab rather than from /var/spool/cron.
When running from /var/spool/cron/myservername, you probably have a permissions problem. Don't redirect the error to /dev/null -- capture them and examine.
Something else to be aware of, cron doesn't initialize the full run environment, which can sometimes mean you can run it just fine from a fully logged-in shell, but it doesn't behave the same from cron.
In the case of above, you don't have a "#!/bin/shell" up top in your script. If root is configured to use something like a regular bourne shell or cshell, the syntax you use to populate your variables will not work. This would explain why it would run, but not populate your files. So if you need it to be ksh, "#!/bin/ksh". It's generally best not to trust the environment to keep these things sane. If you need your profile run the do a ". ~/.profile" up front as well. Or a quick and dirty way to get your relatively full env is to do it from su as such "* * * * * su - root -c "/path/to/script" > /dev/null 2>&1
Just some things I've picked up over the years. You're definitely expecting a ksh based on your syntax, so you might want to be sure it's using it.
Thanks for the tips... used a little bit of each answer to get to the bottom of this.
I did have the interpreter at the top (wasn't shown here), but may have been wrong.
Am using #!/bin/bash now and that works.
Also had to tinker with the permissions of the directory the log files are being dumped in to get things working.

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