ultrix man page for getenv

getenv(3)						     Library Functions Manual							 getenv(3)

Name
       getenv, setenv, unsetenv  - manipulate environment variables

Syntax
       char *getenv(name)
       char *name;

       setenv(name, value, overwrite)
       char *name, value;
       int overwrite;

       void unsetenv(name)
       char *name;

Description
       The  subroutine	searches  the  environment  list for a string of the form name = value and returns a pointer to the string value if such a
       string is present, otherwise returns the value 0 (NULL).  For further information, see

       The subroutine searches the environment list in the same manner as If the string name is not found, a string  of  the  form  name=value	is
       added  to  the environment.  If it is found, and overwrite is non-zero, its value is changed to value.  The subroutine returns 0 on success
       and -1 on failure, where failure is caused by an inability to allocate space for the environment.

       The subroutine removes all occurrences of the string name from the environment.	There is no library provision for completely removing  the
       current environment.  It is suggested that the following code be used to do so.
       static char     *envinit[1];
       extern char     **environ;
       environ = envinit;
       All of these routines permit, but do not require, a trailing equals sign (=) on name or a leading equals sign on value.

See Also
	csh(1), sh(1), execve(2), putenv(3), environ(7)

																	 getenv(3)