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
     _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 0 (NULL) 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, where failure is caused by an
     inability to allocate space for the environment.

     _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.

SEE ALSO
     csh(1), sh(1), execve(2), environ(7)












Printed 11/26/99	 March 20, 1987                         1