2.11BSD#431 - /usr/man/cat3/unsetenv.0

GETENV(3)	    UNIX Programmer's Manual		GETENV(3)


NAME
     getenv, setenv, unsetenv - manipulate environmental vari-
     ables

SYNOPSIS
     char *getenv(name)
     char *name;

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

     void unsetenv(name)
     char *name;

DESCRIPTION
     Getenv searches the environment list (see environ(7)) for a
     string of the form name=value and returns a pointer to the
     string value if such a string is present, and 0 (NULL) if it
     is not.

     Setenv searches the environment list as getenv does; 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.  Setenv returns 0
     on success and -1 on failure, where failure is caused by an
     inability to allocate space for the environment.

     Unsetenv 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), environ(7)


Printed 11/26/99	 March 20, 1987                         1