4.3BSD-Reno/share/man/cat3/unsetenv.0

GETENV(3)		      1990			GETENV(3)



NNAAMMEE
     getenv, putenv, setenv, unsetenv - manipulate environmental
     variables

SSYYNNOOPPSSIISS
     ##iinncclluuddee <<ssttddlliibb..hh>>

     cchhaarr **
     ggeetteennvv((ccoonnsstt cchhaarr **nnaammee));;

     sseetteennvv((ccoonnsstt cchhaarr **nnaammee,, ccoonnsstt cchhaarr **vvaalluuee,, iinntt oovveerrwwrriittee));;

     ppuutteennvv((ccoonnsstt cchhaarr **ssttrriinngg));;

     vvooiidd
     uunnsseetteennvv((ccoonnsstt cchhaarr **nnaammee));;

DDEESSCCRRIIPPTTIIOONN
     _G_e_t_e_n_v searches the environment list (see _e_n_v_i_r_o_n(7)) for a
     string of the form _n_a_m_e==_v_a_l_u_e and returns a pointer to the
     string _v_a_l_u_e if such a string is present, and a NULL pointer
     if it is not.

     _S_e_t_e_n_v searches the environment list as _g_e_t_e_n_v does; if the
     string _n_a_m_e is not found, a string of the form _n_a_m_e==_v_a_l_u_e is
     added to the environment.	If it is found, and _o_v_e_r_w_r_i_t_e is
     non-zero, its value is changed to _v_a_l_u_e.  _S_e_t_e_n_v returns 0
     on success and -1 on failure, setting the external variable
     _e_r_r_n_o.

     _P_u_t_e_n_v takes an argument of the form ``_n_a_m_e=_v_a_l_u_e'' and is
     the equivalent of:

	  setenv(name, value, 1);

     _U_n_s_e_t_e_n_v removes all occurrences of the string _n_a_m_e 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 _n_a_m_e or a leading equals sign on
     _v_a_l_u_e.

EERRRROORRSS
     [ENOMEM]
	  _S_e_t_e_n_v or _p_u_t_e_n_v failed because they were unable to
	  allocate memory for the environment.



Printed 7/27/90                May				1






GETENV(3)		      1990			GETENV(3)



SSEEEE AALLSSOO
     csh(1), sh(1), execve(2), environ(7)

SSTTAANNDDAARRDDSS
     GGeetteennvv conforms to ANSI X3.159-1989 (``ANSI C'').


















































Printed 7/27/90                May				2