2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
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5.3 KiB
Groff
228 lines
5.3 KiB
Groff
.\" $NetBSD: getenv.3,v 1.25 2010/10/26 22:34:33 wiz Exp $
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.\"
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.\" Copyright (c) 1988, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the American National Standards Committee X3, on Information
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.\" Processing Systems.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)getenv.3 8.2 (Berkeley) 12/11/93
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.\"
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.Dd October 25, 2010
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.Dt GETENV 3
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.Os
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.Sh NAME
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.Nm getenv ,
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.Nm getenv_r ,
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.Nm putenv ,
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.Nm setenv ,
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.Nm unsetenv
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.Nd environment variable functions
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdlib.h
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.Ft char *
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.Fn getenv "const char *name"
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.Ft int
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.Fn getenv_r "const char *name" "char *buf" "size_t len"
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.Ft int
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.Fn setenv "const char *name" "const char *value" "int overwrite"
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.Ft int
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.Fn putenv "char *string"
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.Ft int
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.Fn unsetenv "const char *name"
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.Sh DESCRIPTION
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These functions set, unset and fetch environment variables from the
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host
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.Em environment list .
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For compatibility with differing environment conventions,
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the
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.Fn getenv
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or
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.Fn getenv_r
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given argument
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.Ar name
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may be appended with an equal sign
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.Dq Li \&= .
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.Pp
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The
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.Fn getenv
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function obtains the current value of the environment variable
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.Ar name .
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If the variable
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.Ar name
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is not in the current environment, a
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.Dv NULL
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pointer is returned.
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.Pp
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The
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.Fn getenv_r
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function obtains the current value of the environment variable
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.Fa name
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and copies it to
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.Fa buf .
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If
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.Fa name
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is not in the current environment, or the string length of the value of
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.Fa name
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is longer than
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.Fa len
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characters, then \-1 is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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The
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.Fn setenv
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function inserts or resets the environment variable
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.Ar name
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in the current environment list.
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If the variable
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.Ar name
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does not exist in the list,
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it is inserted with the given
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.Ar value .
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If the variable does exist, the argument
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.Ar overwrite
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is tested; if
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.Ar overwrite is
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zero, the
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variable is not reset, otherwise it is reset
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to the given
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.Ar value .
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.Pp
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The
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.Fn putenv
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function takes an argument of the form
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.Dq name=value
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and it will set the environment variable
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.Dq name
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equal to
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.Dq value
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by altering an existing entry, or creating a new one if an existing
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one does not exist.
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The actual string argument passed to
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.Fn putenv
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will become part of the environment.
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If one changes the string, the environment will also change.
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.Pp
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The
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.Fn unsetenv
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function
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deletes all instances of the variable name pointed to by
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.Fa name
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from the list.
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.Sh RETURN VALUES
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The functions
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.Fn getenv_r ,
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.Fn setenv ,
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.Fn putenv ,
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and
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.Fn unsetenv
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return zero if successful; otherwise the global variable
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.Va errno
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is set to indicate the error and a
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\-1 is returned.
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.Pp
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If
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.Fn getenv
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is successful, the string returned should be considered read-only.
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa name
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argument to
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.Fn setenv
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or
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.Fn unsetenv
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is a null pointer, points to an empty string, or points to a string
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containing an
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.Dq Li \&=
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character.
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The
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.Fa value
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argument to
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.Fn setenv
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is a null pointer.
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The
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.Fa string
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argument to
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.Fn putenv
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is a null pointer, or points to a string that either starts with a
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.Dq Li \&=
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character or does not contain one at all.
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.It Bq Er ENOMEM
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The function
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.Fn setenv
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or
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.Fn putenv
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failed because they were unable to allocate memory for the environment.
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.El
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.Pp
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The function
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.Fn getenv_r
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can return the following errors:
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.Bl -tag -width Er
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.It Bq Er ENOENT
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The variable
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.Fa name
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was not found in the environment.
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.It Bq Er ERANGE
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The value of the named variable is too long to fit in the supplied buffer.
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.El
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.Sh SEE ALSO
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.Xr csh 1 ,
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.Xr sh 1 ,
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.Xr execve 2 ,
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.Xr environ 7
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.Sh STANDARDS
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The
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.Fn getenv
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function conforms to
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.St -ansiC .
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The
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.Fn putenv
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function conforms to
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.St -xpg4 .
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The
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.Fn unsetenv
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function conforms to
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.St -p1003.1-2001 .
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.Sh HISTORY
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The functions
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.Fn setenv
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and
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.Fn unsetenv
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appeared in
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.At v7 .
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The
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.Fn putenv
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function appeared in
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.Bx 4.3 Reno .
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