Learning Crontab
 

Hi All,

I have added my first cron job like this:

user@krishnar6:~$ crontab -l | grep -v "#"

* * * * * /home/user/test.sh

user@krishnar6:~$ cat /home/user/test.sh
#!/bin/bash
echo hello!
user@krishnar6:~$

I expected this job to run every minute and print hello output. But it never did. Can you please help me to fix the prob?

Krish

The script will print to stdout, which cron sends to the configured email account.
Unless you have configured that in a sensible way you will never see it.

Try redirecting the output to a file:

Also make sure the script is executable:

It worked!!

I have modified my scrip like this:

user@krishnar6:~$ cat test.sh
#!/bin/bash
echo hello! > crontest.txt
mkdir /home/user/cron

The cron job creates the text file but NOT the folder. I am wondering why folder is not getting created.

Hmm, if all of this is happening as the same user this should actually work.

You can debug this by printing the output to a file. Change the crontab entry to

The 2>&1 redirects stderr to stdout so that everything ends up in the out file.

Please post the content of /tmp/crontab.out after an (unsuccessfull) cron execution.

user@krishnar6:~$ cat /tmp/crontab.out
/home/user/test.sh: line 3: mkdir: command not found
user@krishnar6:~$

Ok, that explains. Cron has a reduced environment. That includes the content of the PATH variable. Therefore it does not find the mkdir executable.

Run
The output will probably be /bin/mkdir or /usr/bin/mkdir.

That is the full path to mkdir. Use that in the script. So e.g.:
For this reason it is good practice to always use absolute paths to commands in cronjobs.

Thanks! That fixed the issue.