projects / thirdparty / man-pages.git / blame
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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. | |
| 11 | .\" | |
| 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| 13 | .\" manual page may be incorrect or out-of-date.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. | |
| 19 | .\" | |
| 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. | |
| 24 | .TH CLEARENV 3 2001-10-17 "Linux Programmer's Manual" | |
| 25 | .SH NAME | |
| 26 | clearenv \- clear the environment | |
| 27 | .SH SYNOPSIS | |
| 28 | .nf | |
| 29 | .B #include <stdlib.h> | |
| 30 | .sp | |
| 31 | .BI "int clearenv(void);" | |
| 32 | .fi | |
| 33 | .SH DESCRIPTION | |
| 63aa9df0 | 34 | The \fBclearenv\fP() function clears the environment of all name-value |
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35 | pairs and sets the value of the external variable |
| 36 | .I environ | |
| 37 | to NULL. | |
| 38 | ||
| 39 | .SH "RETURN VALUE" | |
| 63aa9df0 | 40 | The \fBclearenv\fP() function returns zero on success, and a non-zero |
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41 | value on failure. |
| 42 | .\" Most versions of Unix return -1 on error, or do not even have errors. | |
| f59a3f19 | 43 | .\" Glibc info and the Watcom C library document "a non-zero value". |
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44 | |
| 45 | .SH AVAILABILITY | |
| 46 | Not in libc4, libc5. In glibc since glibc 2.0. | |
| 47 | ||
| 48 | .SH "CONFORMING TO" | |
| 49 | Various Unix variants (DGUX, HPUX, QNX, ...). | |
| 50 | POSIX.9 (bindings for FORTRAN77). | |
| 63aa9df0 | 51 | POSIX.1-1996 did not accept \fBclearenv\fP() and \fIputenv\fP(), |
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52 | but changed its mind and scheduled these functions for some |
| 53 | later issue of this standard (cf. B.4.6.1). However, SUSv3 | |
| 63aa9df0 | 54 | only adds \fIputenv\fP(), and rejected \fBclearenv\fP(). |
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55 | |
| 56 | .SH NOTES | |
| 57 | Used in security-conscious applications. If it is unavailable | |
| 58 | the assignment | |
| 59 | .RS | |
| 60 | .nf | |
| 61 | environ = NULL; | |
| 62 | .fi | |
| 63 | .RE | |
| 64 | will probably do. | |
| 65 | .LP | |
| 66 | The DGUX and Tru64 manpages write: If | |
| 67 | .I environ | |
| 68 | has been modified by anything other than the | |
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69 | .BR putenv (), |
| 70 | .BR getenv (), | |
| fea681da | 71 | or |
| 31e9a9ec | 72 | .BR clearenv () |
| fea681da | 73 | functions, then |
| 63aa9df0 | 74 | .BR clearenv () |
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75 | will return an error and the process environment will remain unchanged. |
| 76 | .\" .LP | |
| 77 | .\" HPUX has a ENOMEM error return. | |
| 78 | .SH "SEE ALSO" | |
| 79 | .BR getenv (3), | |
| 80 | .BR putenv (3), | |
| 81 | .BR setenv (3), | |
| 82 | .BR unsetenv (3), | |
| 83 | .BR environ (5) |