]>
Commit | Line | Data |
---|---|---|
fea681da MK |
1 | .\" Copyright 2001 John Levon <moz@compsoc.man.ac.uk> |
2 | .\" | |
3 | .\" Permission is granted to make and distribute verbatim copies of this | |
4 | .\" manual provided the copyright notice and this permission notice are | |
5 | .\" preserved on all copies. | |
6 | .\" | |
7 | .\" Permission is granted to copy and distribute modified versions of this | |
8 | .\" manual under the conditions for verbatim copying, provided that the | |
9 | .\" entire resulting derived work is distributed under the terms of a | |
10 | .\" permission notice identical to this one. | |
c13182ef | 11 | .\" |
fea681da MK |
12 | .\" Since the Linux kernel and libraries are constantly changing, this |
13 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
14 | .\" responsibility for errors or omissions, or for damages resulting from | |
15 | .\" the use of the information contained herein. The author(s) may not | |
16 | .\" have taken the same level of care in the production of this manual, | |
17 | .\" which is licensed free of charge, as they might when working | |
18 | .\" professionally. | |
c13182ef | 19 | .\" |
fea681da MK |
20 | .\" Formatted or processed versions of this manual, if unaccompanied by |
21 | .\" the source, must acknowledge the copyright and authors of this work. | |
22 | .\" | |
23 | .\" Additions, aeb, 2001-10-17. | |
cc4615cc | 24 | .TH CLEARENV 3 2007-07-26 "Linux" "Linux Programmer's Manual" |
fea681da MK |
25 | .SH NAME |
26 | clearenv \- clear the environment | |
27 | .SH SYNOPSIS | |
28 | .nf | |
29 | .B #include <stdlib.h> | |
30 | .sp | |
0daa9e92 | 31 | .B "int clearenv(void);" |
fea681da | 32 | .fi |
cc4615cc MK |
33 | .sp |
34 | .in -4n | |
35 | Feature Test Macro Requirements for glibc (see | |
36 | .BR feature_test_macros (7)): | |
37 | .in | |
38 | .sp | |
39 | .BR clearenv (): | |
40 | _SVID_SOURCE || _XOPEN_SOURCE | |
fea681da | 41 | .SH DESCRIPTION |
60a90ecd MK |
42 | The |
43 | .BR clearenv () | |
44 | function clears the environment of all name-value | |
fea681da MK |
45 | pairs and sets the value of the external variable |
46 | .I environ | |
47 | to NULL. | |
fea681da | 48 | .SH "RETURN VALUE" |
60a90ecd MK |
49 | The |
50 | .BR clearenv () | |
51 | function returns zero on success, and a non-zero | |
fea681da MK |
52 | value on failure. |
53 | .\" Most versions of Unix return -1 on error, or do not even have errors. | |
f59a3f19 | 54 | .\" Glibc info and the Watcom C library document "a non-zero value". |
a759cc87 | 55 | .SH VERSIONS |
c13182ef MK |
56 | Not in libc4, libc5. |
57 | In glibc since glibc 2.0. | |
fea681da | 58 | .SH "CONFORMING TO" |
e45a6aea | 59 | Various Unix variants (DG/UX, HP-UX, QNX, ...). |
fea681da | 60 | POSIX.9 (bindings for FORTRAN77). |
60a90ecd MK |
61 | POSIX.1-1996 did not accept |
62 | .BR clearenv () | |
d9c1ae64 MK |
63 | and |
64 | .BR putenv (3), | |
fea681da | 65 | but changed its mind and scheduled these functions for some |
c13182ef | 66 | later issue of this standard (cf. B.4.6.1). |
68e1685c | 67 | However, POSIX.1-2001 |
d9c1ae64 | 68 | only adds |
988db661 | 69 | .BR putenv (3), |
d9c1ae64 | 70 | and rejected |
60a90ecd | 71 | .BR clearenv (). |
fea681da | 72 | .SH NOTES |
c13182ef MK |
73 | Used in security-conscious applications. |
74 | If it is unavailable | |
fea681da MK |
75 | the assignment |
76 | .RS | |
77 | .nf | |
7295b7ed | 78 | environ = NULL; |
fea681da MK |
79 | .fi |
80 | .RE | |
81 | will probably do. | |
82 | .LP | |
aa496226 | 83 | The DG/UX and Tru64 man pages write: If |
fea681da MK |
84 | .I environ |
85 | has been modified by anything other than the | |
fb186734 MK |
86 | .BR putenv (3), |
87 | .BR getenv (3), | |
fea681da | 88 | or |
31e9a9ec | 89 | .BR clearenv () |
fea681da | 90 | functions, then |
63aa9df0 | 91 | .BR clearenv () |
fea681da MK |
92 | will return an error and the process environment will remain unchanged. |
93 | .\" .LP | |
68e1685c | 94 | .\" HP-UX has a ENOMEM error return. |
fea681da MK |
95 | .SH "SEE ALSO" |
96 | .BR getenv (3), | |
97 | .BR putenv (3), | |
98 | .BR setenv (3), | |
99 | .BR unsetenv (3), | |
aa949e2d | 100 | .BR environ (7) |