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About linux : Where-can-I-set-environment-variables-that-crontab-will-use

Question Detail

I have a crontab running every hour. The user running it has environment variabless in the .bash_profile that work when the user runs the job from the terminal, however, obviously these don’t get picked up by crontab when it runs.

I’ve tried setting them in .profile and .bashrc but they still don’t seem to get picked up. Does anyone know where I can put environment vars that crontab can pick up?

Question Answer

You can define environment variables in the crontab itself when running crontab -e from the command line.

LANG=nb_NO.UTF-8
LC_ALL=nb_NO.UTF-8
# m h dom mon dow command

* * * * * sleep 5s && echo “yo”

This feature is only available to certain implementations of cron. Ubuntu and Debian currently use vixie-cron which allows these to be declared in the crontab file (also GNU mcron).

Archlinux and RedHat use cronie which does not allow environment variables to be declared and will throw syntax errors in the cron.log. Workaround can be done per-entry:

# m h dom mon dow command
* * * * * export LC_ALL=nb_NO.UTF-8; sleep 5s && echo “yo”

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I got one more solution for this problem:

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

In this case it will pick all the environment variable defined in your $HOME/.profile file.

Of course $HOME is also not set, you have to replace it with the full path of your $HOME.
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Setting vars in /etc/environment also worked for me in Ubuntu. As of 12.04, variables in /etc/environment are loaded for cron.
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Have ‘cron’ run a shell script that sets the environment before running the command.

Always.

# @(#)$Id: crontab,v 4.2 2007/09/17 02:41:00 jleffler Exp $
# Crontab file for Home Directory for Jonathan Leffler (JL)
#—————————————————————————–
#Min Hour Day Month Weekday Command
#—————————————————————————–
0 * * * * /usr/bin/ksh /work1/jleffler/bin/Cron/hourly
1 1 * * * /usr/bin/ksh /work1/jleffler/bin/Cron/daily
23 1 * * 1-5 /usr/bin/ksh /work1/jleffler/bin/Cron/weekday
2 3 * * 0 /usr/bin/ksh /work1/jleffler/bin/Cron/weekly
21 3 1 * * /usr/bin/ksh /work1/jleffler/bin/Cron/monthly

The scripts in ~/bin/Cron are all links to a single script, ‘runcron’, which looks like:

: “$Id: runcron.sh,v 2.1 2001/02/27 00:53:22 jleffler Exp $”
#
# Commands to be performed by Cron (no debugging options)

# Set environment — not done by cron (usually switches HOME)
. $HOME/.cronfile

base=`basename $0`
cmd=${REAL_HOME:-/real/home}/bin/$base

if [ ! -x $cmd ]
then cmd=${HOME}/bin/$base
fi

exec $cmd ${@:+”[email protected]”}

(Written using an older coding standard – nowadays, I’d use a shebang ‘#!’ at the start.)

The ‘~/.cronfile’ is a variation on my profile for use by cron – rigorously non-interactive and no echoing for the sake of being noisy. You could arrange to execute the .profile and so on instead. (The REAL_HOME stuff is an artefact of my environment – you can pretend it is the same as $HOME.)

So, this code reads the appropriate environment and then executes the non-Cron version of the command from my home directory. So, for example, my ‘weekday’ command looks like:

: “@(#)$Id: weekday.sh,v 1.10 2007/09/17 02:42:03 jleffler Exp $”
#
# Commands to be done each weekday

# Update ICSCOPE
n.updics

The ‘daily’ command is simpler:

: “@(#)$Id: daily.sh,v 1.5 1997/06/02 22:04:21 johnl Exp $”
#
# Commands to be done daily

# Nothing — most things are done on weekdays only

exit 0

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If you start the scripts you are executing through cron with:

#!/bin/bash -l

They should pick up your ~/.bash_profile environment variables
……………………………………………………
Expanding on @carestad example, 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.
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Whatever you set in crontab will be available in the cronjobs, both directly and using the variables in the scripts.

Use them in the definition of the cronjob

You can configure crontab so that it sets variables that then the can cronjob use:

$ crontab -l
myvar=”hi man”
* * * * * echo “$myvar. date is $(date)” >> /tmp/hello

Now the file /tmp/hello shows things like:

$ cat /tmp/hello
hi man. date is Thu May 12 12:10:01 CEST 2016
hi man. date is Thu May 12 12:11:01 CEST 2016

Use them in the script run by cronjob

You can configure crontab so that it sets variables that then the scripts can use:

$ crontab -l
myvar=”hi man”
* * * * * /bin/bash /tmp/myscript.sh

And say script /tmp/myscript.sh is like this:

echo “Now is $(date). myvar=$myvar” >> /tmp/myoutput.res

It generates a file /tmp/myoutput.res showing:

$ cat /tmp/myoutput.res
Now is Thu May 12 12:07:01 CEST 2016. myvar=hi man
Now is Thu May 12 12:08:01 CEST 2016. myvar=hi man

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For me I had to set the environment variable for a php application. I resolved it by adding the following code to my crontab.
$ sudo crontab -e

crontab:
ENVIRONMENT_VAR=production

* * * * * /home/deploy/my_app/cron/cron.doSomethingWonderful.php

and inside doSomethingWonderful.php I could get the environment value with:
“production”

I hope this helps!
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Instead of

0 * * * * sh /my/script.sh

Use bash -l -c

0 * * * * bash -l -c ‘sh /my/script.sh’

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You can also prepend your command with env to inject Environment variables like so:

0 * * * * env VARIABLE=VALUE /usr/bin/mycommand

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Expanding on @Robert Brisita has just expand , also if you don’t want to set up all the variables of the profile in the script, you can select the variables to export on the top of the script

In crontab -e file:

SHELL=/bin/bash

*/1 * * * * /Path/to/script/script.sh

In script.sh

#!/bin/bash
export JAVA_HOME=/path/to/jdk

some-other-command

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I’m using Oh-my-zsh in my macbook so I’ve tried many things to get the crontab task runs but finally, my solution was prepending the .zshrc before the command to run.

*/30 * * * * . $HOME/.zshrc; node /path/for/my_script.js

This task runs every 30 minutes and uses .zshrc profile to execute my node command.

Don’t forget to use the dot before the $HOME var.
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I tried most of the provided solutions, but nothing worked at first. It turns out, though, that it wasn’t the solutions that failed to work. Apparently, my ~/.bashrc file starts with the following block of code:

case $- in
*i*) ;;
*) return;;
esac

This basically is a case statement that checks the current set of options in the current shell to determine that the shell is running interactively.
If the shell happens to be running interactively, then it moves on to sourcing the ~/.bashrc file.
However, in a shell invoked by cron, the $- variable doesn’t contain the i value which indicates interactivity.
Therefore, the ~/.bashrc file never gets sourced fully. As a result, the environment variables never got set.
If this happens to be your issue, feel free to comment out the block of code as follows and try again:

# case $- in
# *i*) ;;
# *) return;;
# esac

I hope this turns out useful
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Another way – inspired by this this answer – to “inject” variables is the following (fcron example):
%daily 00 12 \
set -a; \
. /path/to/file/containing/vars; \
set +a; \
/path/to/script/using/vars

From help set:

-a Mark variables which are modified or created for export.
Using + rather than – causes these flags to be turned off.

So everything in between set – and set + gets exported to env and is then available for other scripts, etc. Without using set the variables get sourced but live in set only.
Aside from that it’s also useful to pass variables when a program requires a non-root account to run but you’d need some variables inside that other user’s environment. Below is an example passing in nullmailer vars to format the e-mail header:
su -s /bin/bash -c “set -a; \
. /path/to/nullmailer-vars; \
set +a; \
/usr/sbin/logcheck” logcheck

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Unfortunately, crontabs have a very limited environment variables scope, thus you need to export them every time the corntab runs.
An easy approach would be the following example, suppose you’ve your env vars in a file called env, then:
* * * * * . ./env && /path/to_your/command
this part . ./env will export them and then they’re used within the same scope of your command
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All the above solutions work fine.
It will create issues when there are any special characters in your environment variable.
I have found the solution:
eval $(printenv | awk -F= ‘{print “export ” “\””$1″\”””=””\””$2″\”” }’ >> /etc/profile)
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For me I had to specify path in my NodeJS file.
// did not work!!!!!
require(‘dotenv’).config()

instead
// DID WORK!!
require(‘dotenv’).config({ path: ‘/full/custom/path/to/your/.env’ })

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I found this issue while looking at a similar problem that matched the title, but I am stuck with the environment file syntax that systemd or docker use:
FOO=bar
BAZ=qux

This won’t work for Vishal’s excellent answer because they aren’t bash scripts (note the lack of export).
The solution I’ve used is to read each line into xargs and export them before running the command:
0 5 * * * export $(xargs < $HOME/.env); /path/to/command/to/run ............................................................ Set Globally env sudo sh -c "echo MY_GLOBAL_ENV_TO_MY_CURRENT_DIR=$(pwd)" >> /etc/environment”

Add scheduled job to start a script

crontab -e

*/5 * * * * sh -c “$MY_GLOBAL_ENV_TO_MY_CURRENT_DIR/start.sh”

=)
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what worked for me (debian based):

create a file with all the needed env var :
#!/bin/bash
env | grep VAR1= > /etc/environment
env | grep VAR2= >> /etc/environment
env | grep VAR3= >> /etc/environment

then build the crontab content, by calling the env file before calling the script that needs it, therefore start the cron service
(crontab -l ; echo ‘* * * * * . /etc/environment; /usr/local/bin/python /mycode.py >> /var/log/cron-1.log 2>&1’) | crontab
service cron start

nb : for python use case, be sure to call the whole python path, else wrong python could be invocated, generating non-sense syntax error

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