Environment Variable for good

Jerry Mcguire · 09-09-2011, 05:14 AM

Hello,

I have installed my application to a path, let's say /usr/myapp and defined an environment variable in /etc/bashrc so that everyone knows where myapp is installed to.

Code:

export MYAPP_HOME=/usr/myapp

As long as my pals login interactively, everything looks good. Yet when it comes to scheduled jobs in the crontab, the /etc/bashrc doesn't get sourced and therefore no such variable defined.

At first my solution was to include the line at the top of the `crontab -e` as:

Code:

MYAPP_HOME=/usr/myapp
0 18 * * 1-5  sh $MYAPP_HOME/scripts/some-script

It worked, but it didn't seem right to do so because any further modification of the variable in /etc/bashrc would not be effective in the user's cron job list, which was difficult to maintain and created confusion.

I wonder if there is any way to make an environment variable globally effective in any login or any user's cron job. e.g. like $TOMCAT_HOME.

Any ideas? Thanks.

J.

John VV · 09-09-2011, 05:35 AM

then do not add it to a SHELL start-up
that file is read when a user logs in or bash is ran

for a red hat based system set that at boot
set it in a script in "/etc/profile.d"

Jerry Mcguire · 09-09-2011, 10:16 AM

Code:

$ cat /etc/profile.d/myapp.sh 
#!/bin/bash
export MYAPP_HOME=/usr/myapp

$ crontab -l
* * * * *   echo "printng \$MYAPP_HOME as \"${MYAPP_HOME}\" ." >~/out.log

$ cat ~/out.log
printng $MYAPP_HOME as "" .

$

Have I missed something?

John VV · 09-09-2011, 02:34 PM

a bit yes - a very basic with no checks

Code:

#!/bin/bash

MYAPP_HOME=/usr/myapp

export MYAPP_HOME

colucix · 09-09-2011, 04:37 PM

Basically you want the shell to act as a login shell. This is achieved using option -l either in the sha-bang at the beginning of the script or by executing the script itself using bash -l. In both cases the file .bash_profile is sourced.

Anyway, your case is a bit different since you want to set an environment variable and use it inside the same command line (so that using bash -l $MYAPP_HOME/scripts/some-script will fail because the variable is substituted with a null string before the .bash_profile is sourced). A workaround can be to explicitly source .bash_profile in the same command line, e.g.

Code:

0 18 * * 1-5  . $HOME/.bash_profile && $MYAPP_HOME/scripts/some-script

Jerry Mcguire · 09-10-2011, 09:42 AM

I guess I'll have to combine the suggestions of both of yours. Thanks.

Any further suggestions welcomed.

tredegar · 09-10-2011, 10:29 AM

Quote:

Any further suggestions welcomed.

OK.

Why don't you just put your app at a location that is on everyone's $PATH, like /usr/local/bin/ ?

Then they don't care where it is, and they can run it just by typing its name.

Jerry Mcguire · 09-10-2011, 11:34 PM

umm.. It's not a couple of tools/scripts that I am looking at. It's more like an installation of a tree structure, with a app home directory, it's own bin,dat,rpt and stuff. Anyway, it's not designed as everybody's tool.