setenv(3) [ultrix man page]

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)

getenv(3C)						   Standard C Library Functions 						getenv(3C)

NAME

       getenv - return value for environment name

SYNOPSIS

       #include <stdlib.h>

       char *getenv(const char *name);

DESCRIPTION

       The  getenv()  function	searches  the environment list (see environ(5)) for a string of the form name=value and, if the string is present,
       returns a pointer to the value in the current environment.

RETURN VALUES

       If successful, getenv() returns a pointer to the value in the current environment; otherwise, it returns a null pointer.

USAGE

       The getenv() function can be safely called from a multithreaded	application.   Care  must  be  exercised  when	using  both  getenv()  and
       putenv(3C)  in  a multithreaded application.  These functions examine and modify the environment list, which is shared by all threads in an
       application.  The system prevents the list from being accessed simultaneously by two different threads.	It does not, however, prevent  two
       threads from successively accessing the environment list using  getenv() or putenv(3C).

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       exec(2), putenv(3C), attributes(5), environ(5), standards(5)

SunOS 5.11							    24 Jul 2002 							getenv(3C)