ba174a5e38
Not because I admit they are technically wrong and not because of bug reports (I receive nothing). But because I surprisingly meets so strong opposition and resistance so lost any desire to continue that. Anyone who interested in POSIX can dig out what changes and how through cvs diffs.
174 lines
4.3 KiB
Groff
174 lines
4.3 KiB
Groff
.\" Copyright (c) 1988, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to Berkeley by
|
|
.\" the American National Standards Committee X3, on Information
|
|
.\" Processing Systems.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)getenv.3 8.2 (Berkeley) 12/11/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd October 12, 2006
|
|
.Dt GETENV 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm getenv ,
|
|
.Nm putenv ,
|
|
.Nm setenv ,
|
|
.Nm unsetenv
|
|
.Nd environment variable functions
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In stdlib.h
|
|
.Ft char *
|
|
.Fn getenv "const char *name"
|
|
.Ft int
|
|
.Fn setenv "const char *name" "const char *value" "int overwrite"
|
|
.Ft int
|
|
.Fn putenv "const char *string"
|
|
.Ft void
|
|
.Fn unsetenv "const char *name"
|
|
.Sh DESCRIPTION
|
|
These functions set, unset and fetch environment variables from the
|
|
host
|
|
.Em environment list .
|
|
For compatibility with differing environment conventions,
|
|
the given arguments
|
|
.Fa name
|
|
and
|
|
.Fa value
|
|
may be appended and prepended,
|
|
respectively,
|
|
with an equal sign
|
|
.Dq Li \&= .
|
|
.Pp
|
|
The
|
|
.Fn getenv
|
|
function obtains the current value of the environment variable,
|
|
.Fa name .
|
|
The application should not modify the string pointed
|
|
to by the
|
|
.Fn getenv
|
|
function.
|
|
.Pp
|
|
The
|
|
.Fn setenv
|
|
function inserts or resets the environment variable
|
|
.Fa name
|
|
in the current environment list.
|
|
If the variable
|
|
.Fa name
|
|
does not exist in the list,
|
|
it is inserted with the given
|
|
.Fa value .
|
|
If the variable does exist, the argument
|
|
.Fa overwrite
|
|
is tested; if
|
|
.Fa overwrite
|
|
is zero, the
|
|
variable is not reset, otherwise it is reset
|
|
to the given
|
|
.Fa value .
|
|
.Pp
|
|
The
|
|
.Fn putenv
|
|
function takes an argument of the form ``name=value'' and is
|
|
equivalent to:
|
|
.Bd -literal -offset indent
|
|
setenv(name, value, 1);
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Fn unsetenv
|
|
function
|
|
deletes all instances of the variable name pointed to by
|
|
.Fa name
|
|
from the list.
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn getenv
|
|
function returns the value of the environment variable as a
|
|
.Dv NUL Ns
|
|
-terminated string.
|
|
If the variable
|
|
.Fa name
|
|
is not in the current environment,
|
|
.Dv NULL
|
|
is returned.
|
|
.Pp
|
|
.Rv -std setenv putenv
|
|
.Sh ERRORS
|
|
.Bl -tag -width Er
|
|
.It Bq Er ENOMEM
|
|
The function
|
|
.Fn setenv
|
|
or
|
|
.Fn putenv
|
|
failed because they were unable to allocate memory for the environment.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr csh 1 ,
|
|
.Xr sh 1 ,
|
|
.Xr execve 2 ,
|
|
.Xr environ 7
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn getenv
|
|
function conforms to
|
|
.St -isoC .
|
|
.Sh HISTORY
|
|
The functions
|
|
.Fn setenv
|
|
and
|
|
.Fn unsetenv
|
|
appeared in
|
|
.At v7 .
|
|
The
|
|
.Fn putenv
|
|
function appeared in
|
|
.Bx 4.3 Reno .
|
|
.Sh BUGS
|
|
Successive calls to
|
|
.Fn setenv
|
|
or
|
|
.Fn putenv
|
|
assigning a differently sized
|
|
.Fa value
|
|
to the same
|
|
.Fa name
|
|
will result in a memory leak.
|
|
The
|
|
.Fx
|
|
semantics for these functions
|
|
(namely, that the contents of
|
|
.Fa value
|
|
are copied and that old values remain accessible indefinitely) make this
|
|
bug unavoidable.
|
|
Future versions may eliminate one or both of these
|
|
semantic guarantees in order to fix the bug.
|