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getenv.0
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1992-08-10
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GETENV(3) UNIX Programmer's Manual GETENV(3)
NNAAMMEE
ggeetteennvv, ppuutteennvv, sseetteennvv, uunnsseetteennvv - environment variable functions
SSYYNNOOPPSSIISS
##iinncclluuddee <<ssttddlliibb..hh>>
_c_h_a_r _*
ggeetteennvv(_c_o_n_s_t _c_h_a_r _*_n_a_m_e)
_i_n_t
sseetteennvv(_c_o_n_s_t _c_h_a_r _*_n_a_m_e, _c_o_n_s_t _c_h_a_r _*_v_a_l_u_e, _i_n_t _o_v_e_r_w_r_i_t_e)
_i_n_t
ppuutteennvv(_c_o_n_s_t _c_h_a_r _*_s_t_r_i_n_g)
_v_o_i_d
uunnsseetteennvv(_c_o_n_s_t _c_h_a_r _*_n_a_m_e)
DDEESSCCRRIIPPTTIIOONN
These functions set, unset and fetch environment variables from the host
_e_n_v_i_r_o_n_m_e_n_t _l_i_s_t. For compatibility with differing environment conven¡
tions, the given arguments _n_a_m_e and _v_a_l_u_e may be appended and prepended,
respectively, with an equal sign ``=''.
The ggeetteennvv() function obtains the current value of the environment vari¡
able, _n_a_m_e. If the variable _n_a_m_e is not in the current environment , a
null pointer is returned.
The sseetteennvv() function inserts or resets the environment variable _n_a_m_e in
the current environment list. If the variable _n_a_m_e does not exist in the
list, it is inserted with the given _v_a_l_u_e_. If the variable does exist,
the argument _o_v_e_r_w_r_i_t_e is tested; if _o_v_e_r_w_r_i_t_e _i_s zero, the variable is
not reset, otherwise it is reset to the given _v_a_l_u_e.
The ppuutteennvv() function performs the equivalent of:
setenv(name, value, 1);
The uunnsseetteennvv() function deletes all instances of the variable name point¡
ed to by _n_a_m_e from the list.
RREETTUURRNN VVAALLUUEESS
The functions sseetteennvv() and ppuutteennvv() return zero if successful; otherwise
the global variable _e_r_r_n_o is set to indicate the error and a -1 is re¡
turned.
EERRRROORRSS
[ENOMEM] The function sseetteennvv() or ppuutteennvv() failed because they were un¡
able to allocate memory for the environment.
SSEEEE AALLSSOO
csh(1), sh(1), execve(2), environ(7)
SSTTAANNDDAARRDDSS
The ggeetteennvv() function conforms to ANSI C3.159¡1989 (``ANSI C'').
HHIISSTTOORRYY
The functions sseetteennvv() and uunnsseetteennvv() appeared in Version 7 AT&T UNIX.
The ppuutteennvv() function appeared in 4.3BSD-Reno.
BSD Experimental June 29, 1991 1