I've a file called /root/run.sh in which following code has been wrote
/usr/bin/watch -n1 "echo hello >> /root/out.txt"
If I launch manually in terminal it in the following manner
bash /root/run.sh
all works fine.
Now I want that this file is called every time I start my os, so I modified the cronjob file through crontab -e and added the following line:
#reboot bash /root/run.sh
Unfortunately, it doesn't work, that means that after the reboot it doesn't write 'hello' in the out.txt file.
If I modify the run.sh script in the following manner:
echo hello >> /root/out.txt
then all works fine, that means after the reboot it writes one time the word 'hello' in the out.txt file.
How can I use the cronjob to execute a watch command?
I solved the problem writing bash /root/run.sh in the file located in /etc/rc.local. Now all works fine but I wonder why I can't put it in the cronjob list through #reboot
Related
I want to make a simple cron job that moves all the files on my desktop to a temp folder at the end of the day. for debugging
I wrote this bash script that works when I run it using bash:
#!/bin/bash
/bin/mv ~/Desktop/* ~/Temp
saved the script and I am using the following cron job:
59 23 * * * /bin/mv /Users/username/Desktop/* /Users/username/Temp
The cron job executes when I tested printing something to a file. but somehow it will not move files? Is there something I am missing?
Suggesting to fix your bash script with correct user context.
Since ~ is defined by user's context.
It is possible to replace each ~ with $HOME path:
sed -i "s|~|$HOME|g" your-script.sh
And/Or include users context in your script:
sed -i "2i source $HOME/.bash_profile" your-script.sh
I'm novice to running bash script. (you can suggest me, if title I've given is incorrect.)
I want to run a jar file using bash script in loop. Then it should write the output of jar command into some file.
Bash file datagenerate.sh
#!/bin/bash
echo Total iterations are 500
for i in {1..500}
do
the_output="$(java -jar data-generator.jar 10 1 mockData.csv data_200GB.csv)"
echo $the_output
echo Iteration $i processed
done
no_of_lines="$(wc -l data_200GB.csv)"
echo "${no_of_lines}"
I'm running above script using command nohup sh datagenerate.sh > datagenerate.log &. As I want to run this script in background, so that even I log out from ssh it should keep running & output should go into datagenerate.log.
But when I ran above command and hit enter or close the terminal it ends the process. Only Total iterations are 500 is getting logged into output file.
Let me know what I'm missing. I followed following two links to create above shell script: link-1 & link2.
nohup sh datagenerate.sh > datagenerate.log &
nohup should work this way without using screen program, but depending on your distro your sh shell might be linked to dash.
Just make your script executable:
chmod +x datagenerate.sh
and run your command like this:
nohup ./datagenerate.sh > datagenerate.log &
You should check this out:
https://linux.die.net/man/1/screen
With this programm you can close your shell while a command or script is still running. They will not be aborted and you can pick the session up again later.
I'm currently trying to run script that will run in the background when my AWS instance boots for the duration of the instance life. I'm testing it with a simple script to see if it works, before I test with my more complicated one:
#!/bin/bash
while [true]; do
sleep 1
echo "Hello World" >> "tempStorage.json"
done
And my sudo crontab -l returns:
# All the comment stuff
#reboot sh /home/ubuntu/test/testScript/test.sh
Which is the path to the script. I've also obviously run chmod +x test.sh to make sure its an executable.
The problem is when I stop and then start the AWS instance there's nothing in the tempStorage.json file. I've checked other threads and they all suggest this is what I should be doing, so I'm very confused and advice would be appreciated. Thanks.
As Mark B mentioned, the issue is the execution directory of the cron script. There are two solutions then.
A) Change the path to file as Mark B recommended so the script would look something like:
#!/bin/bash
while [true]; do
sleep 1
echo "Hello World" >> "/home/ubuntu/test/testScript/tempStorage.json"
done
B) Change the directory of the cron execution and keep the script as it was. This works better if you need to put the script in any directory. It would look like this for the crontab:
# All the comment stuff
#reboot cd /home/ubuntu/test/testScript && sh test.sh
That should work fine. I think the issue is that you aren't giving the full path to the tempSTorage.json file within your script. So it is being written to in a different folder than the one you are looking in, specifically whatever folder cron starts processes in by default. Try changing it to something like /tmp/tempSTorage.json and then rebooting the server again.
Note that if you are wanting something that starts on boot and runs forever, this probably isn't the best method. In that case I would look into running your process as a service.
I have a bash script start.sh which calls another run.sh, which takes me to another prompt where I have to delete a file file.txt and then exit out of that prompt.
When I call run.sh from inside start.sh, I see the prompt and I believe that it deletes the file.txt but the inner/new prompt waits for me to exit out of it while the script is running - meaning it needs intervention to proceed. How do I avoid it in bash?
In Python I can use Popen and get it going but not sure about bash.
EDIT: I would rather like to know what command to provide to exit out of the shell (generated from running run.sh") so I can go back to the prompt where "start.sh" was started.
Etan: To answer your question
VirtualBox:~/Desktop/ > ./start
company#4d6z74d:~$ ->this is the new shell
company#4d6z74d:~$ logout ---> I did a "Control D here" so the script could continue.
Relevant part of start.sh which:
/../../../../run.sh (this is the one that takes us to the new $ prompt)
echo "Delete file.txt "
rm -f abc/def/file.txt
You can run run.sh in the background using &. In start.sh, you would invoke the script via /path/run.sh &. Now, start.sh will exit without waiting for run.sh to finish (which is running in the background).
I know this has been asked many times, but I can find a suitable answer in my case.
I croned a backup script using rsync and would like to see all output, errors or not, from the all script commands. I must write the command inside the script itself, and do not want to see output in my shell.
I have been trying with no success. Below part of the script.
#!/bin/bash
.....
BKLOG=/mnt/backup_error_$now.txt
# Log everything to log file
# something like
exec 2>&1 | tee $BKLOG
# OR
exec &> $BKLOG
I have been adding at the script beginig all kinds of exec | tee $BKLOG with adding &>, 2>&1at various part of the command line, but all failed. I either get an empty log file or incomplete. I need to see on log file what rsync has done, and the error if script failed before syncing.
Thank you for help. My shell is zsh, so any solution in zsh is welcomed.
To redirect all the stdout/stderr to a file place this line on top of your script:
BKLOG=/mnt/backup_error_$now.txt
exec &> "$BKLOG"