In my crontab file I execute a script like so (I edit the crontab using sudo crontab -e):
01 * * * * bash /etc/m/start.sh
The script runs some other scripts like so:
sudo bash -c "/etc/m/abc.sh --option=1" &
sleep 2
sudo bash -c "/etc/m/abc.sh --option=2" &
When cron runs the script start.sh, I do ps aux | grep abc.sh and I see the abc.sh script running.
After a couple of seconds, the script is no longer running, even though abc.sh should take hours to finish.
If I do sudo bash /etc/m/start.sh & from the command line, everything works fine (the abc.sh scripts run for hours in the background until they complete).
How do I debug this?
Is there something I'm doing that is preventing these scripts from running in the background until they are done?
The program(s) you're starting might be expecting a terminal to send their output to, or receive input from.
If you set the MAILTO= variable, and you have a sendmail(-like) daemon installed, you will get an email with the error message(s) it prints, if there are any:
MAILTO=your#email.address.here.com
01 * * * * bash /path/to/something.sh
Another way to debug would be to run the script from the command line, while redirecting all inputs and outputs:
$ sudo bash -c "foo.sh" > output_file 2>&1 < /dev/null
Also, the system log files (usually found in /var/log) might contain useful hints.
Related
Working in Debian 8.5.
The installed cronjob looks like this:
SHELL=/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
*/1 * * * * /usr/local/bin/MySript.sh
#---------------------------------------------------------------
The bash script looks like this:
#!/bin/bash
cd /home/Path/to/executable/C/program
sh -c "xterm -e ./Cprogram" &
exit
When I execute the C program with ./MyScript.sh, the bash window pops up and the C program runs.
Cron won't run the script. The Daemon is running and cron is executing, as I see in /var/log/syslog
I overviewed all priviliges and I do everything as root.
I'd be very happy for any advice. Thanks in advance, JS
I read the other related topics but they didn't help me.
I have a shell script which checks if my python script is not running,it will run it. Otherwise it will just skip and do nothing.
It totally works when I use:
bash myshellscrip.sh
And I get the result that I want which is doing some tasks and sending emails to some correspondents. However, when I try to run this particular shell script on crontab, it doesn't send out the emails and doesn't do the other tasks.
I tried the following on crontab and none of them worked.
* * * * * /bin/bash /path/to/my/script/myshellscrip.sh
* * * * * /bin/bash /path/to/my/script/myshellscrip.sh >> /some/other/path/output.txt
When I save the changes into 'output.txt' file, it creates the file but it doesn't send the emails or doing other tasks.
I also tried the option of reboot because I need this program to run at start up too, and this didn't work:
#reboot /bin/bash /path/to/my/script/myshellscrip.sh
Does anyone know how to fix it?
EDIT:
As I was checking with the simplest shell scrip like:
#!/bin/sh
/usr/bin/python /home/pi/DCA/code.py
My crontab wouldn't have any output in my output.txt file although my code.py have something printing out, too.
However, when I use a very simple python code for example only a 'print' statement it will run and save the output into output.txt.
Seems like your shell script crashes / stops before it can do something (possibly due to the environment being different or permission issues). You can check /var/log/syslog to find out.
You could try removing /bin/bash, I don't think that's necessary?
Run the cron job in debug mode. for that, Add -x to the bash command on the cronjob and save their output in the file.
bash -x /path/to/script.sh >> /path/to/the/output.txt
You can find the problem.
Apparently crontab was running my script several times. So I tried to use different locking mechanisms to put a lock around my scrip but only using flock worked for me. In my crontab I added this line:
* * * * * /usr/bin/flock -n /tmp/ms.lockfile /bin/bash /path/to/my/script/myShellScript.sh
I want to simulate a wallpapers slideshow (pictures are fetched from unsplash.com) almost the same as on Windows 7 but on Ubuntu. So for this purpose I decide to use unsplash-wallpaper.
I created a bash script .refresh-wallpaper.sh and placed it to home direcotry:
#!/bin/bash
unsplash-wallpaper -r --dir "~/Pictures/wallpapers"
Then I install a crontab:
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
* * * * * sh ~/.refresh-wallpaper.sh >/dev/null 2>&1
The script runs by crond but nothing happened:
Dec 17 22:12:01 pcname CRON[11933]: (username) CMD (sh ~/.refresh-wallpaper.sh >/dev/null 2>&1)
..but it works when it launched manually via terminal:
username#pcname:~$ sh .refresh-wallpaper.sh
Request https://source.unsplash.com/random
Downloading [==================================================================]
✔︎ Image saved to /home/username/Pictures/wallpapers/wallpaper-photo-1511620356826-e2ed21a61991.jpg
Check it out.
What I do wrong? Thanks for any interaction!
EDIT1: It works because new images are saved and output redirects to the log but wallpapers doesn't check out on desktop.
I assume that the quotation marks in your script prevent the expansion of ~ in this line:
unsplash-wallpaper -r --dir "~/Pictures/wallpapers"
I suggest to use:
unsplash-wallpaper -r --dir "$HOME/Pictures/wallpapers"
Following is the entry in the crontab:
MAILTO=abc#gmail.com
45 14 * * * /home/user/simple.sh
I've also done chmod +x on the simple.sh But the crontab does not run, it doesn't even send an email.
pgrep cron shows an Id. I also tried bouncing crond. But no luck!
Could someone please point out the mistake here
The simple.sh script is:
#! /bin/bash
echo hello
Thanks
Since you are doing a echo within the cron job script, you need to capture its output somewhere.
Your shebang and file mode (using chmod +x) are all right, so those aren't the issue here and running without /bin/sh should work fine.
Try using the following to see the output in cron.log file (This runs every minute)
* * * * * /home/user/simple.sh >> /home/user/cron.log
Note that cron jobs run in separate subprocess shell, with reduced environment, so its output won't be visible on your terminal.
Regarding sending of email - you need to have some mail package (like postman, mutt etc) configured for the cron daemon to send out error mails.
Do not use relative paths, but absolute ones. Also, indicate the binary running the script, that is /bin/sh (or whatever coming from which sh):
45 14 * * * /bin/sh /path/to/script/simple.sh
Maybe there shouldn't be a space in line 1 of your .sh script:
#! /bin/bash
to
#!/bin/bash
Although I could see why it would still seem to work from when invoked in an interactive shell (# could merely comment out the rest of the line).
Still, I'd guess at worst it'd merely ignore that line and inherit cron's interpreter of /bin/sh
Asterisk check script is not running only when run by crontab, but runs by ./script.sh and sh script.sh. Here is the script:
date
asterisk -rx "show channels"
asterisk -rx "zap show channels"
Then I >> into a log file. When I run manually via ./ or sh with >> log.log it works, just not as a crontab listed as
* * * * * /root/script.sh
I have tried adding #!/bash/sh at the top of the script and only the date is shown no matter what I try. I am a noob to bash scripts and I'm trying to learn.
Since feature requests to mark a comment as an answer remain declined, I copy the above solution here.
Have you checked your path? It's almost certainly different when run under cron. (You can set PATH=... in your crontab. From the command line, type "echo $PATH" to see what you're expecting.) It might be more standard to provide full paths to date, asterisk and your log file inside script.sh (e.g., "/bin/date /path/to/asterisk ....") – mjk