[SOLVED] bash cronjob script to kill openvpn and run client.ovpn

toxine · 06-08-2018, 03:43 PM

Hello,

I am trying to write a script to kill openvpn and and start a new openvpn instance every hour. the script runs fine if I run it in terminal but cant get crontab to work.

my current settings:

Code:

#!/bin/sh
killall openvpn
openvpn /home/user/nyc.ovpn

things I have done:

Quote:

systemctl enable crond
Edited /etc/crontab
inserted:
0 */1 * * * /home/user/killallopenvpn.sh
chmod +x /home/user/killallopenvpn.sh

what am i doing wrong?

username_11011 · 06-08-2018, 04:06 PM

I'm trying to understand the "/1" part? This is a sample from *my* crontab file:

Code:

# Run hourly cron jobs at 47 minutes after the hour:
47 * * * * /usr/bin/run-parts /etc/cron.hourly 1> /dev/null

So, my assumption would be that all you need is "0 * * * *".

toxine · 06-08-2018, 04:10 PM

Quote:

Originally Posted by username_11011

I'm trying to understand the "/1" part? This is a sample from *my* crontab file:

Code:

# Run hourly cron jobs at 47 minutes after the hour:
47 * * * * /usr/bin/run-parts /etc/cron.hourly 1> /dev/null

So, my assumption would be that all you need is "0 * * * *".

I have fixed it. I also included @reboot for testing but still will not run at reboot.

michaelk · 06-08-2018, 04:26 PM

Code:

* = */1

/etc/crontab is a system wide crontab which has an addition column for "run as user"

Code:

# m h dom mon dow user	command
  0 *  *   *   *  user  /home/user/killallopenvpn.sh

Replace user with the actual username.

username_11011 · 06-08-2018, 04:36 PM

Also, make sure your cron daemon is running. I usually kill mine, first (otherwise, you could start multiple daemons):

Code:

killall crond
crond

toxine · 06-08-2018, 06:33 PM

still cannot get it to work

Code:

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name  command to be executed
45 * * * *	omar    /home/omar/killallopenvpn.sh
@reboot         omar    /home/omar/killallopenvpn.sh
# m h dom mon dow user  command
  28 *  *   *   *  omar  /home/omar/killallopenvpn.sh

scasey · 06-08-2018, 06:47 PM

While you haven't specifically said what you mean by "can't get it to work," please note that scripts run from cron have no environment defined, so some specific issues could be:
the location of killall is unknown
the location of openvpn is unknown

When writing a script, best practice is to use absolute paths to all commands.
Alternatively, define the PATH variable in the script.

username_11011 · 06-08-2018, 06:58 PM

Quote:

While you haven't specifically said what you mean by "can't get it to work," please note that scripts run from cron have no environment defined, so some specific issues could be:
the location of killall is unknown
the location of openvpn is unknown

When writing a script, best practice is to use absolute paths to all commands.
Alternatively, define the PATH variable in the script.

Yes!!! This is correct. Change all commands in your script to absolute paths. Or, define the PATH variable manually at the beginning of the script:

Code:

PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin

toxine · 06-09-2018, 04:43 PM

Hello,

Thank you everyone for the replies. Unfortunately still cannot get to to run. I have edited the paths, Script runs fine from bash so the updated defined paths are correct.

My etc/crontab with different parameters.

Code:

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name  command to be executed
15 * * * *	omar    /home/omar/killallopenvpn.sh
@reboot         omar    /home/omar/killallopenvpn.sh
# m h dom mon dow user  command
  12 *  *   *   *  omar  /home/omar/killallopenvpn.sh
15 * * * *	/home/omar/killallopenvpn.sh
@reboot         /home/omar/killallopenvpn.sh

my killallopenvpn.sh script

Code:

#!/bin/bash
/usr/bin/killall openvpn
/usr/sbin/openvpn --config /home/omar/nyc.ovpn

username_11011 · 06-09-2018, 05:08 PM

When you test your script manually, you run it as omar-- right? You don't su to root? Or, run the script with sudo? Ex:

Code:

sudo /home/omar/killallopenvpn.sh

If not, I would suggest trying something simpler for cron to run. Possibly:

Code:

15 * * * * echo "text" > ~/out.txt

Obviously, "15" can be "12" or "16" or whatever time is coming up, so cron will run this right away. Then of course, restart your cron daemon to make the change:

Code:

killall crond
crond

After the time has passed when the job should run, check out.txt and verify cron wrote "text" to ~/out.txt. If this works, we know there's an issue with your script. If cron won't even echo (which is shell builtin), then something more bizarre is going on. If you *are* running your script as root or sudo when it works, you may need to tell cron to run it as root or sudo.

scasey · 06-09-2018, 05:33 PM

I'm sorry, I'm still not clear about "cannot get it to run"
Are you saying that cron is not executing the script?
Or that the script is not doing what you expect?
How do you know?
What does the cron log say? It should report if the job was executed. (mine is at /var/log/cron)
Please clarify which you think the problem is...

username_11011 has a good point about the user. In the crontab you've posted you are running the job at 12 with user omar, and at 15 with no user (so root, I think). Can a non-root user kill and restart openvpn? I don't know.

username_11011's idea about a test is also good, except the '~' means 'this user's home directory'...and there's no user, exactly. Suggest defining an absolute path there as well:

Code:

15 * * * * echo "text" > /home/omar/out.txt

Edit: Why do you need to kill and restart openvpn at boot?

Edit2: Is openvpn a service (guessing from your posted syntax re: cron)? Should it be?

toxine · 06-10-2018, 12:42 AM

Quote:

Originally Posted by username_11011

When you test your script manually, you run it as omar-- right? You don't su to root? Or, run the script with sudo? Ex:

Code:

sudo /home/omar/killallopenvpn.sh

If not, I would suggest trying something simpler for cron to run. Possibly:

Code:

15 * * * * echo "text" > ~/out.txt

Obviously, "15" can be "12" or "16" or whatever time is coming up, so cron will run this right away. Then of course, restart your cron daemon to make the change:

Code:

killall crond
crond

After the time has passed when the job should run, check out.txt and verify cron wrote "text" to ~/out.txt. If this works, we know there's an issue with your script. If cron won't even echo (which is shell builtin), then something more bizarre is going on. If you *are* running your script as root or sudo when it works, you may need to tell cron to run it as root or sudo.

i run the script i created as root.
I tried to test echo but cron failed to create out.txt

pan64 · 06-10-2018, 04:54 AM

Code:

15 * * * * echo "text" > ~/out.txt

probably echo not found too - use full path, and you ought to use explicit path instead of ~

michaelk · 06-10-2018, 06:39 AM

What distribution/version are you running?

Have you checked the logs to see if the cron job was started?

If you added the echo test to /etc/crontab then you need to use the full path to out.txt and you still to specify a user.

toxine · 06-10-2018, 08:34 AM

Thanks everyone! got it to work.

Fixed it by temp disabling selinux. chmod +x the script. Defining absolute paths. running command as root if required (do not leave it blank).