Problems running a rails script using cron

Question

Here's my cron task:

0,30 * * /home/USERNAME/webapps/APPNAME/RAILS-FOLDER/script/rails runner -e production /home/USERNAME/webapps/APPNAME/RAILS-FOLDER/script-name.rb

It fails with the following error:

/usr/bin/env: ruby: No such file or directory

OK, so ruby does not exist in the environment. I suspect my path. A quick search of StackOverflow suggests adding the path to the ruby executable to $PATH. So I modified ~/.profile by adding this line:

export PATH=/usr/local/bin:$PATH

Now nothing is happening. I was getting error messages by email (using MAILTO=[redacted]@gmail.com at the head of my crontab) but I'm no longer getting them. I cannot tell if cron is even running after my changes. BTW, the email messages I did receive lacked a valid "From", which makes me wonder if gmail is just deleting them. How else can I log what happens when my cron task exectues?

Answer 1

This is indeed a PATH-related issue. However, rather than using a ~/.profile file, we normally recommend simply using the full path to the executable; for example:

0 * * * * /usr/local/bin/ruby /home/USERNAME/webapps/APPNAME/RAILS-FOLDER/script/rails

For reference, here is cron's entire environment:

# cron's environment:
USER=<username>
SHELL=/bin/sh
PATH=/usr/bin:/bin
PWD=/home/<username>
SHLVL=1
HOME=/home/<username>
LOGNAME=<username>

Another thing we notice is that your cron job does not appear to use the correct number of time specifiers at the beginning; i.e, you are using:

0,30 * *

But this should probably be:

0,30 * * * *

As for logging, sending emails will general work if the crontab fails, but won't have an effect in the case of a syntax error. You can also submit a support ticket and we can provide some relevant lines from the cron log file.

Problems running a rails script using cron

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