How can I run a cron command with existing environmental variables?

Question

How can I run a cron command with existing environmental variables?

If I am at a shell prompt I can type echo $ORACLE_HOME and get a path. This is one of my environmental variables that gets set in my ~/.profile. However, it seems that ~/.profile does not get loaded fron cron scripts and so my scripts fail because the $ORACLE_HOME variable is not set.

In this question the author mentions creating a ~/.cronfile profile which sets up variables for cron, and then he does a workaround to load all his cron commands into scripts he keeps in his ~/Cron directory. A file like ~/.cronfile sounds like a good idea, but the rest of the answer seems a little cumbersome and I was hoping someone could tell me an easier way to get the same result.

I suppose at the start of my scripts I could add something like source ~/.profile but that seems like it could be redundant.

So how can I get make my cron scripts load the variables from my interactive-shell profile?

Answer 1

In the crontab, before you command, add . $HOME/.profile. For example:

0 5 * * * . $HOME/.profile; /path/to/command/to/run

Cron knows nothing about your shell; it is started by the system, so it has a minimal environment. If you want anything, you need to have that brought in yourself.

Answer 2

Another option, which I find easier, is to run the script with cron and have the environment in the script.

In crontab -e file:

SHELL=/bin/bash

*/1 * * * * $HOME/cron_job.sh

In cron_job.sh file:

#!/bin/bash
source $HOME/.bash_profile
some_other_cmd

Any command after the source of .bash_profile will have your environment as if you logged in.

Answer 3

Another option, which I find easier, is to run the script with cron and tell bash to login (hence using /etc/profile.d/... environment definitions)

In crontab -e file:

*/1 * * * * bash -l -c './cron_job.sh'
*/1 * * * * bash -l -c 'php -f ./cron_job.php'

Any command after the source of .bash_profile will have your environment as if you logged in.

Answer 4

Q: How can I run a cron command with existing environmental variables?

The general practice is to specifically set all required environmental variables in a script that is to be run from a cron job.

Answer 5

This syntax definitely helps you. I do not understand the syntax, but it works. Oracle uses this syntax, when deploys Oracle Configuration Manager to crontab, hence, I believe that this is a right solution.

0 5 * * * SOME_ENV_VAR=some_value some_command some_parameters

Answer 6

You can put global environment variables in /etc/environment. They are loaded when a program is run by the crontab. Ex :

env | grep ORACLE_HOME >> /etc/environment
service crontab restart

The drawback is that it is not restricted to a single user. Tested under CentOS7

Answer 7

Add

BASH_ENV=/home/user/.profile

to the crontab. See How to guarantee availability of $BASH_ENV

Answer 8

I recently came across a case where I had to execute the overall cronjob as root but, at the same time, had to execute a subcommand as a different user (which required sourcing that user's environment). I went with the following approach:

# m  h  dom  mon  dow  user  command
*/5  *   *    *    *   root  (sudo -i -u <the user> command-to-be-run-as-user) && command-to-be-run-as-root

The crucial part is the argument -i that's being passed to sudo which will execute the given command in a separate login shell (which in turn means that the user's dotfiles will be sourced).

PS: Note that the user column is only available in /etc/crontab and the /etc/cron.d/* files.

Answer 9

Instead of setting profile, what helped me was setting the PATH. Some of the commands were not available in my cron scripts as the PATH is different.

ENVIRONMENT=prod
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
*/30 * * * * /opt/myscript1.sh
*/30 * * * * /opt/myscript2.sh
*/30 * * * * /opt/myscript3.sh

Setting PATH with the path of commands helped me. Even better if you can use a template and detemplatize later,

ENVIRONMENT={{ENVIRONMENT}}
PATH={{PATH}}
*/30 * * * * /opt/myscript1.sh
*/30 * * * * /opt/myscript2.sh
*/30 * * * * /opt/myscript3.sh

Passing variables to each item looks messy.

Answer 10

The solution, which worked for me, is described here.

You create a wrapper script, which calls . ~/.cronfile, and then does the things you want. This script is launched by cron.

In ~/.cronfile you specify the environment for your cron jobs.

Answer 11

This is an old Question, and it has 11 answers as of today. I'm submitting the 12th answer b/c: 1) none of the others actually worked for me, and 2) I feel this answer is different.

The OP asked:

How can I run a cron command with existing environmental variables?

The OP also stated his preference for an answer that was less cumbersome than some others he had considered. Hopefully, this answer is the least cumbersome.

A less cumbersome approach is to use the --login option of su to import the user's (nearly) complete environment. This can be done without resort to the authentication requirement that usually accompanies su - if it is run from the root crontab.

This may be illustrated with a simple example. This example uses mpg123 - an MP3 audio player. However, many other examples could be constructed from commands that (like mpg123) require various environment variables to work properly, and these environment variables are often set without user notification.

mpg123 can ordinarily be run from the CLI without much difficulty. For example, to play a file in a continuous loop (after making the Bluetooth device connection):

$ mpg123 --loop -1 ~/rainstorm.mp3

But if we try to run this as a cron job, we may run into issues :) The issues are that cron typically has an austere environment, and that mpg123 depends on environment variables that are un-specified (and unclear).

We may resolve these issues as follows (pi is user pi):

  ... open the root crontab
$ sudo crontab -e
   ... add one line:

@reboot su pi -l -c /home/pi/start-mpg123.sh > /home/pi/start-mpg123.log 2>&1

start-mpg123.sh is straightforward; it sets up the BT connection, and then starts mpg123:

#!/usr/bin/bash

sleep 5
if [ "$(/usr/bin/bluetoothctl devices Connected)" != "Device DF:45:E9:00:BE:8B OontZ Angle solo DS E8B" ]; then
    /usr/bin/bluetoothctl connect DF:45:E9:00:BE:8B
fi
/usr/bin/mpg123 --loop -1 /home/pi/rainstorm.mp3

Answer 12

I put . ~/.dbus/session-bus/* at the top of my desired script :)