# 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

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