I have set a specific cronjob (crontab -e), but it doesn't works like I thought. I don't get what's wrong.
Here is what I do (root cron):
#reboot /path/to/my_script.sh start
25 18 * * * halt
The first line as expected is running my_script.sh, but when time comes for the server to shutdown, nothing happen. Is the #reboot option made to work alone?
There is no option in cron to run at shutdown. #reboot is meant to run the script on start
If you want to run a script at shutdown, you need to write an initd script and register it for the shutdown run level. The standard runlevel for halt is 0, the run level for restart is 6. I've verified this for Debian, Gentoo and Redhat systems but it seems to be true across *NIX systems. Check this for more info.
Related
I have a discord bot running on a raspberry pi that i need to restart every day, I'm trying to do this through crontab but with no luck.
It manages to kill the active screen processes but never starts an instance, not that I can see with "screen -ls" and I can tell that it doesn't create one that I can't see as the bot itself does not come online.
Here is the script:
#!/bin/bash
sudo pkill screen
sleep 2
screen -dmS discordBot
sleep 2
screen -S "discordBot" -X stuff "node discordBot/NEWNEWNEWN\n"
Here is also the crontab:
0 0 * * * /bin/bash /home/admin/discordBot/script.sh
Is it possible to have crontab run a screen session? And if so how?
Previously I tried putting the screen command stright into cron but now I have it in a bash script instead.
If I run the script in the terminal it works perfectly, it’s just cron where it fails. Also replacing "screen" with the full path "/usr/bin/screen" does not change anything.
So the best way of doing it, without investigating the underlying problem would be to create a systemd service and putting a restart command into cron.
/etc/systemd/system/mydiscordbot.service:
[Unit]
Description=A very simple discord bot
[Service]
Type=simple
ExecStart=node /path/to/my/discordBot.js
[Install]
WantedBy=multi-user.target
Now you can run your bot with systemctl start mydiscordbot and can view your logs with journalctl --follow -u mydiscord bot
Now you only need to put
45 2 * * * systemctl restart discordbot
into root's crontab and you should be good to go.
You probably should also write the logs into a logfile, maybe /var/log/mydiscordbot.log, but how and if you do that is up to you.
OLD/WRONG ANSWER:
cron is run with a minimal environment, and depending on your os, /usr/bin/ is probably not in the $PATH var. screen is mostlikely located at /usr/bin/screen, so cron can't run it because it can't find the screen binary. try replacing screen in your script with /usr/bin/screen
But the other question here is: Why does your discord bot need to be restarted every day. I run multiple bots with 100k+ users, and they don't need to be restarted at all. Maybe you should open a new question with the error and some code snippets.
I don't know what os your rpi is running, but I had a similar issue earlier today trying to get vms on a server to launch a terminal and run a python script with crontab. I found a very easily solution to automatically restart it on crashes, and to run something simply in the background. Don't rely on crontab or an init service. If your rpi as an x server running, or anything that can be launched on session start, there is a simple shell solution. Make a bash script like
while :; do
/my/script/to/keep/running/here -foo -bar -baz >> /var/log/myscriptlog 2>&1
done
and then you would start it on .xprofile or some similar startup operation like
/path/to/launcher.sh &
to have it run the background. It will restart automatically everytime it closes if started in something like .xprofile, .xinitrc, or anything ran at startup.
Then maybe make a cronjob to restart the raspberry pi or whatever system is running the script but this script wil restart the service whenever it's closed anyway. Maybe you can put that cronjob on a script but I don't think it would launch the GUI.
Some other things you can do to launch a GUI terminal in my research with cronjob that you can try, though they didn't work for my situation on these custom linux vms, and that I read was a security risk to do this from a cronjob, is you can specify the display.
* * * * * DISPLAY=:0 /your/gui/stuff/here
but you would would need to make sure the user has the right permissions and it's considered an unsafe hack to even do this as far as I have read.
for my issue, I had to launch a terminal that stayed open, and then changed to the directory of a python script and ran the script, so that the local files in directory would be called in the python script. here is a rough example of the "launcher.sh" I called from the startup method this strange linux distro used lol.
#!/bin/sh
while :; do
/usr/bin/urxvt -e /bin/bash -c "cd /path/to/project && python loader.py"
done
Also check this source for process management
https://mywiki.wooledge.org/ProcessManagement
I am new to setting up cronjobs and I'm trying to do it on a virtual machine in google compute engine. After a bit of research, I found this StackOverflow question: Running Python script at Regular intervals using Cron in Virtual Machine (Google Cloud Platform)
As per the answer, I managed to enter the crontab -e edit mode and set up a test cronjob like 10 8 * * * /usr/bin/python /scripts/kite-data-pull/dataPull.py. I also checked the system time, which was in UTC, and entered the time according to that.
The step I'm supposed to take, as per the answer, is to run sudo systemctl restart cron which is throwing an error for me:
sudo systemctl restart cron
System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down
Any suggestions on what I can do to set up this cronjob correctly?
Edit a cron jobs with crontab -e and inset a line:
* * * * * echo test123 > /your_homedir_path/file.log
That will write test123 every minute into file.log file.
Then do tail if and wait a couple minutes. You should see test123 lines appearing in the file (and screen).
If it runs try running your python file but first make your .py file executable with "chmod +x script.py"
Here you can find my reply to similar question.
I am trying to schedule my debian jessie machine to shutdown at 9:00 p.m. every 3 days. I currently use a cronjob:
00 21 */3 * * root bash /home/pi/scripts/reboot.sh
where reboot.sh is:
sudo reboot
The machine shuts down on schedule but what is strange is that it just keeps rebooting for several times. how am I able to get rid of this issue. is this related to maybe the RTC clock no have enough time to update itself and so the cron job still thinks the time is still 9... I really doubt this.. any help
its better to use the internal command shutdown instead of using the script. shutdown now shuts the computer and -r flag is for reboot system. you can also pass specific time instead of now like shutdown -r 11:00.
For now you can use
shutdown -r now
I have a simple script that stops and starts the services (of Oracle Hyperion)
#!bin/ksh
/path/to/dir/stop.sh
sleep 1200
/path/to/dir/start.sh
I have scheduled it for every night and it does run, however there is an issue with database connectivity afterwards. But when i run stop.sh and start.sh manually, there is no such issue. Obviously the job had not run completely.
Here's the output from crontab -l
00 02 * * * /export/home/oracle/scheduled_restart.sh
Could someone please advise on the problem? Thanks.
The usual cause for cron jobs to differ from command line during execution of the exact same code is environment, specifically the variables like ORACLE_SID, TWO_TASK, LD_LIBRARY_PATH, and so on.
Assuming the oracle user own the crontab:
When a job is run by crond it does the equivalent of su oracle, not su - oracle. Try doing something to ensure that the command sources everything the oracle user would normally source during login.
To see what is going on:
/export/home/oracle/scheduled_restart.sh && set > /tmp/my_variables.txt
You do not need the /bin/sh if the /export/home/oracle/scheduled_restart.sh file is executable.
It should have a shebang on line 1. ex: #!/bin/ksh for korn shell or whatever shell you use.
I have an embedded device running busybox. The device has crond installed and running, but has no atd daemon. I need to schedule task to run at a given time (just once, not periodically). I know, that the "kosher" way is to use at command, but I unfortunately don't have one. So, how can I use cron as a workaround?
You can set up the cron to run your script, and when it succeeds, the script should just comment out or remove the cron entry.