Using Linux environmental variables as a path in Perl script

Question

I am trying to use an environmental variable to point to a file, run it through a subroutine and associate it with a variable. I managed it with Windows but I cannot get the syntax working for Linux..

This is what I have:

 my $config = read_config("$ENV{APP_HOME}/config/APP-linux.cfg");

my script dies when reaching this line with the error:

    Use of uninitialized value $ENV{"APP_HOME"} in concatenation (.) or string at ./XXXXX.pl

APP_HOME is defined as an environment variable (confirmed using set). What am I doing wrong?

does echo $APP_HOME returns the correct value from your shell? — Hunter McMillen
– Hunter McMillen, Commented Jun 5, 2014 at 16:44
@HunterMcMillen it doesnt... it gives: Name "main::APP_HOME" used only once: possible typo at ./test.pl line 8. Can't call method "echo" on an undefined value at ./test.pl line 8. — AMcNall
– AMcNall, Commented Jun 5, 2014 at 16:47
What does this display: perl -e 'print "$ENV{APP_HOME}\n";' — Hunter McMillen
– Hunter McMillen, Commented Jun 5, 2014 at 17:24
Examine your full list of environment variables: perl -MData::Dumper -e 'print Dumper \%ENV' — Miller
– Miller, Commented Jun 5, 2014 at 18:23

bobbogo · Accepted Answer · 2014-06-05 19:52:32Z

1

In bash, = simply creates a shell variable. These are not automatically exported to the environment. You need to do that explicitly.

Set a shell variable:

 $ AA=hello

Set and export another one (in a single statement):

 $ export BB=there

Start a new process:

 $ bash

Voila! Only the exported variable is inherited by the new process:

 $ echo "[$AA] [$BB]"
 [] [there]

Note that set does not set a variable. set AA=hello does not do what the Windows shell does.

answered Jun 5, 2014 at 19:52

bobbogo

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AMcNall · Accepted Answer · 2014-06-06 08:39:46Z

0

Okay, the solution was of my own stupidity. I set the variable in .bashrc using:

APP_HOME=$HOME/APP/DATA/STORAGE; export FINE_DIR

The RAPID_DIR had no right to be there. Was a remainder of a copy/paste and poor oversight... Changes FINE_DIR to APP_HOME and all is good.

Thankyou for all the guidance!

answered Jun 6, 2014 at 8:39

AMcNall

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