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diff --git a/man3/clearenv.3 b/man3/clearenv.3 new file mode 100644 index 000000000..f800ff47e --- /dev/null +++ b/man3/clearenv.3 @@ -0,0 +1,83 @@ +.\" Copyright 2001 John Levon <moz@compsoc.man.ac.uk> +.\" +.\" Permission is granted to make and distribute verbatim copies of this +.\" manual provided the copyright notice and this permission notice are +.\" preserved on all copies. +.\" +.\" Permission is granted to copy and distribute modified versions of this +.\" manual under the conditions for verbatim copying, provided that the +.\" entire resulting derived work is distributed under the terms of a +.\" permission notice identical to this one. +.\" +.\" Since the Linux kernel and libraries are constantly changing, this +.\" manual page may be incorrect or out-of-date. The author(s) assume no +.\" responsibility for errors or omissions, or for damages resulting from +.\" the use of the information contained herein. The author(s) may not +.\" have taken the same level of care in the production of this manual, +.\" which is licensed free of charge, as they might when working +.\" professionally. +.\" +.\" Formatted or processed versions of this manual, if unaccompanied by +.\" the source, must acknowledge the copyright and authors of this work. +.\" +.\" Additions, aeb, 2001-10-17. +.TH CLEARENV 3 2001-10-17 "Linux Programmer's Manual" +.SH NAME +clearenv \- clear the environment +.SH SYNOPSIS +.nf +.B #include <stdlib.h> +.sp +.BI "int clearenv(void);" +.fi +.SH DESCRIPTION +The \fBclearenv()\fP function clears the environment of all name-value +pairs and sets the value of the external variable +.I environ +to NULL. + +.SH "RETURN VALUE" +The \fBclearenv()\fP function returns zero on success, and a non-zero +value on failure. +.\" Most versions of Unix return -1 on error, or do not even have errors. +.\" Glibc info and the Watcom C library document "a nonzero value". + +.SH AVAILABILITY +Not in libc4, libc5. In glibc since glibc 2.0. + +.SH "CONFORMING TO" +Various Unix variants (DGUX, HPUX, QNX, ...). +POSIX.9 (bindings for FORTRAN77). +POSIX.1-1996 did not accept \fBclearenv()\fP and \fIputenv()\fP, +but changed its mind and scheduled these functions for some +later issue of this standard (cf. B.4.6.1). However, SUSv3 +only adds \fIputenv()\fP, and rejected \fBclearenv()\fP. + +.SH NOTES +Used in security-conscious applications. If it is unavailable +the assignment +.RS +.nf + environ = NULL; +.fi +.RE +will probably do. +.LP +The DGUX and Tru64 manpages write: If +.I environ +has been modified by anything other than the +.IR putenv() , +.IR getenv() , +or +.IR clearenv() +functions, then +.BR clearenv() +will return an error and the process environment will remain unchanged. +.\" .LP +.\" HPUX has a ENOMEM error return. +.SH "SEE ALSO" +.BR getenv (3), +.BR putenv (3), +.BR setenv (3), +.BR unsetenv (3), +.BR environ (5) |