I am setting up a cron job using crontab -e on a machine where I do not have a root privilege.
The initial command in crontab is like this:
0 10 * * * /bin/bash /path/myscript.sh >/path/log
I found the script did not run, since the system created an empty log file. Then I add 2>&1 at the end of the above command:
0 10 * * * /bin/bash /path/myscript.sh >/path/log 2>&1
And try to find errors of whatsoever. Strangely, with adding the 2>&1, cron did not even create an empty log file. Nothing.
Any idea on what's going on here when adding the 2>&1?
The default behaviour of cron is to send stderr via email to the user running the cronjob.
From man cron:
When executing commands, any output is mailed to the owner of the
crontab (or to the user specified in the MAILTO environment
variable in the crontab, if such exists).
To circunvent this behaviour, you can indeed redirect the stderr like you are trying. However, it needs some extra tuning.
As seen in Redirect stderr with date to log file from Cron, you can use a subshell to redirect stderr to stdin and then redirect everything normally: (cron expression 2>&1) > /your/log/file. In your case:
0 10 * * * (/bin/bash /path/myscript.sh 2>&1) >/path/log
Related
By default crontab jobs stdout is sent to the email of the crontab user like the crontab file says in the description:
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
I want to use slacktee same as using (tee) to post a message to slack inside the script run by crontab.
In other scripts (daily scheduled by putting them in /etc/cron.daily/ directory) I do this:
echo "New message!" | slacktee -i "tada" -c "messages"
And when they run, there are no issues. But in my custom scheduled script I see no message on slack though they run correctly.
My job starts every four hours with this scheduling:
* */4 * * * /scripts/mysql_backup.sh
I've tried many redirecting (inside the script, inside the cron command) but anything seems working.
How can I use slacktee inside my custom sheduled script?
EDIT:
I'm a bit late sorry for that and thanks for all your time.
#PhilDenfer no, slacktee does not log anything on /tmp.
#Gedge i've tried sudo echo "test" | slacktee.sh and it works. Also using su and then doing echo "test" | slacktee.sh works.
#isp-zax cron jobs runs successfully because the script makes the backup of the database.
Redirecting the stderr I got slacktee.sh command not found. So using slacktee.hs as root works but not when root uses it in crontab scheduled job (in a daily scheduled script i use slacktee successfully). Why?
Redirecting the stderr I got slacktee.sh command not found. So using slacktee.hs as root works but not when root uses it in crontab scheduled job (in a daily scheduled script i use slacktee successfully). Why?
Because the PATH variable for user root and for user cron are different.
Instead of just 'slacktee' use a full path, i.e. /usr/local/bin/slacktee and it should work OK.
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
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
I'm trying to setup a crontab I have this in my current job in the current user I'm logged into
* * * * * /CS/day/get_info.sh
get_info.sh is supposed to output a text file every minute and I suspected that it would output a file in the same directory as the script is located but it doesn't.
I've also checked the syslogs to see if I could figure this out.
(user) CMD (/CS/day/get_info.sh)
(user) MAIL (mailed 46 bytes of output but got status 0x0001#012)
Can someone explain to me why this is happening?
Thanks
man cron tells you:
When executing commands, any output is mailed to the owner of the
crontab (or to the user named in the MAILTO environment variable in the
crontab, if such exists). The children copies of cron running these
processes have their name coerced to uppercase, as will be seen in the
syslog and ps output.
So you have to
cd into the appropriate directory yourself (cron will use $HOME)
redirect ANY output to a file of your choice
You can do both things in the crontab. But I recommend to do it in the first lines of the script itself:
#!/bin/bash
cd WHEREEVER_YOU_WANT
exec > YOUR_LOG_FILE 2&>1
The script is run in the home directory of the user and the file should be there as well. If you want it in the same directory as the script, either do a cd in your script or modify your crontab entry:
*/1 19-20 * * * cd /CS/day; /CS/day/get_info.sh
Another common problem with crontab entries is the environment. If the script works correctly in your terminal, try debugging it, when it is run from cron:
40 11 * * * bash -x /CS/day/get_info.sh >/tmp/get_info.sh.log 2>&1
Run it once only with current time, because otherwise you will overwrite your log file every minute.
On my case, I just had to install and configure an smtp client.
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.