[ILUG] environment variables

[Harry Moreau]

On 25 May, hrishy samant wrote:
> hi linux gurus
> 
> i wanna know where environmental variables are stored
> the file name.i am running redhat 6.2.i have installed
> xine but every time it starts it asks me to set the
> display variable.which i do by keying in 
> export DISPLAY=ursula:0.0
> echo $DISPLAY
> ursula:0.0
> 

Environment variables are not stored anywhere.
To get the variable set every time you log in add the export command
to your .bash_profile

general sh syntax...
DISPLAY=ursula:0.0 ; export DISPLAY

or bash specific syntax...

export DISPLAY=ursula:0.0

The export command causes a shell variable to be put in the environment
and it becomes visible to all child processes.  It's passed to child processes
in an infrequently used  third argument to main()
Here's a code snippet to print it out.
However don't try to modify the environment using this pointer, the whole thing is packed tight.
putenv(3), setenv(3) or equivalent must be used to modify the environment in C

#include <stdio.h>

int main (int argc, char** argv, char** envp)
{
    char** ep;
    if (envp != 0) {
	for (ep = envp; *ep; ep++) {
	    printf ("%s\n", *ep);
	}
    }
    return 0;
}
-- 
--Harry Moreau----------------