C library function - getenv()

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Description

The C library function char *getenv(const char *name) searches for the environment string pointed to by name and returns the associated value to the string.

Declaration

Following is the declaration for getenv() function.

char *getenv(const char *name)

Parameters

• name − This is the C string containing the name of the requested variable.

Return Value

This function returns a null-terminated string with the value of the requested environment variable, or NULL if that environment variable does not exist.

Example

The following example shows the usage of getenv() function.

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

int main () {
   printf("PATH : %s\n", getenv("PATH"));
   printf("HOME : %s\n", getenv("HOME"));
   printf("ROOT : %s\n", getenv("ROOT"));

   return(0);
}

Let us compile and run the above program that will produce the following result −

PATH : /sbin:/usr/sbin:/bin:/usr/bin:/usr/local/bin
HOME : /
ROOT : (null)