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
Related
I'm using ack as part of a bash script to build a list of MP4 files from a mysqldump. The dump file is about 15mb.
Here's my line:
ack -o "https??://cdn.host.com\S+?\.mp4" /home/me/.dump.sql > /home/me/.mp4-matches.txt
It works fine when running bash script by hand. We get this in .mp4-matches.txt:
https://cdn.host.com/url/t_Foo/Foo.mp4
https://cdn.host.com/url/t_Bar/Bar.mp4
But when running the very same command by itself as a cronjob, it produces an empty file.
I can't figure out why it's not working in cron.
I've tried fiddling with PATH, SHELL, etc in the crontab to try ensure environment is the same as running it by hand. Nothing made a difference.
I've tried using all hard paths in crontab to ack /usr/bin/ack just to be sure. Didn't make a difference.
I've tried using bash -l to start the script. Didn't make a difference.
What am I doing wrong?
Edits for further info:
I am running Debian 7 but I also tested on Ubuntu 18.04 and same issue appears there too.
Server is running exim4, all working. Nothing is being sent to the MAILTO address about this line in the cron.
There's nothing in /var/log/syslog or /var/log/messages concerning errors from cron
Using bash #!/bin/bash
There are no percent signs (%) anywhere in the crontab.
Crontab looks like this:
MAILTO=myemail#address.com
BASH=/bin/bash
SHELL=/bin/bash
PATH=/usr/local/bin:/usr/bin:/bin
27 9 * * * /usr/bin/ack -o "https??://cdn.host.com\S+?\.mp4" /home/me/.dump.sql > /home/me/.mp4-matches.txt
Yes, it's my crontab, not root.
There is no .ackrc file being read. It does not exist anywhere on my system. find / -iname ".ackrc" returned nothing.
A simple expression "https://cdn.host.com/url/t_Foo/Foo.mp4" still returns an empty file in cron.
Both single quotes and double quotes produce empty file in cron.
STERR seems to provide nothing also. Running /usr/bin/ack -o 'https://cdn.host.com/url/t_Foo/Foo.mp4' /home/me/.dump.sql > /home/me/.mp4-matches.txt 2> /home/me/.ackerror.txt returned both .mp4-matches.txt and .ackerror.txt files as 0 bytes.
This should work:
* * * * * ack -o "https??://cdn.host.com\S+?\.mp4" /home/me/.dump.sql </dev/null > /home/me/.mp4-matches.txt
Also you probably can use your line with the the --nofilter option
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 very very rarely use Linux and so don't have any experience with bash scripts and cron jobs.
This is in fact my first attempt. So it's probably something really simple to fix.
I have the following:
/etc/cron.d/clear-mixtape-dir.sh
permissions are: 644
#!/bin/bash
# Clears the /tmp/mixtape2 directory
rm -rf "/tmp/mixtape2/"*
My crontab file looks like so:
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/
*/15 * * * * /etc/cron.d/clear-mixtape-dir.sh >/dev/null 2>&1
I'm trying to execute the .sh script every 15 minutes.
Everything i've found says this should work, but it doesn't.
Does anything like file permissions (on files within /tmp/mixtape2/) matter in this case?
Or perhaps the permissions set on the actual .sh script - maybe they need setting to executable?
Any advice appreciated.
Remove the .sh extension from the script in /etc/cron.d and it will be called.
run-parts ignores files with a period in the name, so the .sh extension is preventing your script from running.
From man cron -
Files must conform to the same naming convention as used by run-parts(8): they must consist solely of upper- and lower-case letters, digits, underscores, and hyphens.
Note: These comments refer to /etc/crontab.
Before doing anything else, which cron are you accessing crontab -e or
su -vim
<your-favorite-editor> /etc/crontab
If you are using crontab -e, then no user field exists in that form of crontab. That might be why you're not running.
In your example, your user field is *. I would make it root or a user that has proper permissions.
Before running this program, I would make a dummy crontab entry that just does
echo "Hello" and runs every minute. Get that to work on which ever crontab you're editing (crontab -e or vim /etc/crontab). Then using that as a template, get your script to run.
Next, see if cron is running:
ps -ef | grep cron
If it is not running, become root and start it by enter
/etc/init.d/cron start (Ubuntu and Red Hat).
You already have a good answer suggesting you add root as the user because of a permissions problem. I'm going to suggest more things to help you debug. I have run into a lot of cron problems over the years.
1) Set the email to a known address, unless you will continually monitor root's email
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/local/bin:/usr/bin
MAILTO=fred#somewhere.com
HOME=/
2) Until everything runs properly, take out the >/dev/null 2>&1 out of your cron entry, so you see the outputs in your email generated after the script runs.
3) Bump */15 down to an interval greater than it takes your script to run -- likr */5, so the script runs more often.
4) I do not know the exact reason, but scripts I run out of cron have to set up their own environments despite being run as that user in cron. This may include steps like cd /home/script-owner and running source .bashrc and calling other script(s) that set environment variables.
*/15 * * * * root /etc/cron.d/clear-mixtape-dir.sh >/dev/null 2>&1
Add user root because your permission seems to be only for root.
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.
I have a bash script mysql_cron.sh that runs mysqldump
#!/bin/bash
/usr/local/mysql/bin/mysqldump -ujoe -ppassword > /tmp/somefile
This works fine. I then call it from cron:
20 * * * * /home/joe/mysql_cron.sh
and this creates the file /tmp/somefile, but the file is always empty. I have tried adding a
source /home/joe/.bash_profile
to the script to make sure cron has the right env variables, but that doesn't help. I see many other people having this problem but have found no solution. I've also tried the '>' operator in the crontab to cat any cron errors to a file, but that doesn't seem to generate any errors. Any troubleshooting ideas welcomed. Thanks!
Add output of error information to file (as Damp has said), so that you can check if there is any error:
#!/bin/bash
/usr/local/mysql/bin/mysqldump -ujoe -ppassword > /tmp/somefile 2>&1
You can also take a look at MySQL's log files at /var/log in case there is some hint there.
Add this line to your script and compare the result between running it from cron versus running it directly:
env > /tmp/env.$$.out
The $$ will be replaced in the resulting filename by the PID of the parent process (cron or the shell). You should be able to diff the two files and see if anything significant is different between the two environments.