getenv() -- General Function (libc)

Read environmental variable
#include <stdlib.h>
char *getenv(VARIABLE) char *VARIABLE;

A program may read variables  from its environment. This allows the program
to accept information that is  specific to it.  The environment consists of
an array of strings, each  having the form VARIABLE=VALUE. When called with
the string VARIABLE, getenv()  reads the environment, and returns a pointer
to the string VALUE.

Example

This example prints the environmental variable PATH.

#include <stdio.h>
#include <stdlib.h>

main()
{
    char *env;
    extern char *getenv();

    if ((env = getenv("PATH")) == NULL) {
        printf("Sorry, cannot find PATH\n");
        exit(1);
    }
    printf("PATH = %s\n", env);
}

See Also

environmental variables,
envp,
exec,
libc,
putenv(),
sh,
stdlib.h
ANSI Standard, §7.10.4.4
POSIX Standard, §4.6.1

Diagnostics

When VARIABLE is not found or has no value, getenv() returns NULL.

© 2012 by Stephen A. Ness