How to get CRON to call in the correct PATHs

Question

I used /etc/crontab. I used vi and entered in the PATHs I needed into this file and ran it as root. The normal crontab overwrites PATHs that you have set up. A good tutorial on how to do this.

The systemwide cron file looks like this:

This has the username field, as used by /etc/crontab.
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file.
# This file also has a username field, that none of the other crontabs do.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# m h dom mon dow user   command
42 6 * * *   root    run-parts --report /etc/cron.daily
47 6 * * 7   root    run-parts --report /etc/cron.weekly
52 6 1 * *   root    run-parts --report /etc/cron.monthly
01 01 * * 1-5 root python /path/to/file.py

Most likely, cron is running in a very sparse environment. Check the environment variables cron is using by appending a dummy job which dumps env to a file like this:

* * * * * env > env_dump.txt

Compare that with the output of env in a normal shell session.

You can prepend your own environment variables to the local crontab by defining them at the top of your crontab.

Here's a quick fix to prepend $PATH to the current crontab:

# echo PATH=$PATH > tmp.cron
# echo >> tmp.cron
# crontab -l >> tmp.cron
# crontab tmp.cron

The resulting crontab will look similar to chrissygormley's answer, with PATH defined before the crontab rules.

You should put full paths in your crontab. That's the safest option.
If you don't want to do that you can put a wrapper script around your programs, and set the PATH in there.

e.g.

01 01 * * * command

becomes:

01 01 * * * /full/path/to/command

Also anything called from cron should be be very careful about the programs it runs, and probably set its own choice for the PATH variable.

EDIT:

If you don't know where the command is that you want execute which <command> from your shell and it'll tell you the path.

EDIT2:

So once your program is running, the first thing it should do is set PATH and any other required variable (e.g. LD_LIBRARY_PATH) to the values that are required for the script to run.
Basically instead of thinking how to modify the cron environment to make it more suitable for your program/script - make your script handle the environment it's given, by setting an appropriate one when it starts.

Adding a PATH definition into the user crontab with correct values will help... I've filled mine with this line on top (after comments, and before cron jobs):

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

And it's enough to get all my scripts working... Include any custom path there if you need to.

Setting PATH right before the command line in my crontab worked for me:

* * * * * PATH=$PATH:/usr/local/bin:/path/to/some/thing

Make your variables work for you, this will allow access t

Define your PATH in /etc/profile.d/*.sh

System-wide environment variables

Files with the .sh extension in the /etc/profile.d directory get executed whenever a bash login shell is entered (e.g. when logging in from the console or over ssh), as well as by the DisplayManager when the desktop session loads.

You can for instance create the file /etc/profile.d/myenvvars.sh and set variables like this:

export JAVA_HOME=/usr/lib/jvm/jdk1.7.0
export PATH=$PATH:$JAVA_HOME/bin

Execute crontab with login option!

CRONTAB run script or command with Environment Variables

0 9 * * * cd /var/www/vhosts/foo/crons/; bash -l -c 'php -f ./download.php'
0 9 * * * cd /var/www/vhosts/foo/crons/; bash -l -c download.sh