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
263 lines
6.8 KiB
Groff
263 lines
6.8 KiB
Groff
.\" $NetBSD: exec.3,v 1.21 2010/03/22 19:30:53 joerg Exp $
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.\"
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.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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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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.\" @(#)exec.3 8.3 (Berkeley) 1/24/94
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.\"
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.Dd May 6, 2005
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.Dt EXEC 3
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.Os
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.Sh NAME
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.Nm execl ,
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.Nm execlp ,
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.Nm execle ,
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.Nm exect ,
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.Nm execv ,
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.Nm execvp
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.Nd execute a file
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Vt extern char **environ;
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.Ft int
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.Fn execl "const char *path" "const char *arg" ...
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.Ft int
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.Fn execlp "const char *file" "const char *arg" ...
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.Ft int
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.Fn execle "const char *path" "const char *arg" ... "char *const envp[]"
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.Ft int
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.Fn exect "const char *path" "char *const argv[]" "char *const envp[]"
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.Ft int
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.Fn execv "const char *path" "char *const argv[]"
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.Ft int
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.Fn execvp "const char *file" "char *const argv[]"
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.Sh DESCRIPTION
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The
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.Nm exec
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family of functions replaces the current process image with a
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new process image.
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The functions described in this manual page are front-ends for the function
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.Xr execve 2 .
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(See the manual page for
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.Xr execve 2
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for detailed information about the replacement of the current process.
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The
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.Xr script 7
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manual page provides detailed information about the execution of
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interpreter scripts.)
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.Pp
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The initial argument for these functions is the pathname of a file which
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is to be executed.
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.Pp
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The
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.Fa "const char *arg"
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and subsequent ellipses in the
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.Fn execl ,
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.Fn execlp ,
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and
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.Fn execle
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functions can be thought of as
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.Em arg0 ,
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.Em arg1 ,
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\&...,
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.Em argn .
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Together they describe a list of one or more pointers to null-terminated
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strings that represent the argument list available to the executed program.
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The first argument, by convention, should point to the file name associated
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with the file being executed.
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The list of arguments
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.Em must
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be terminated by a
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.Dv NULL
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pointer.
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.Pp
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The
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.Fn exect ,
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.Fn execv ,
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and
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.Fn execvp
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functions provide an array of pointers to null-terminated strings that
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represent the argument list available to the new program.
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The first argument, by convention, should point to the file name associated
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with the file being executed.
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The array of pointers
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.Sy must
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be terminated by a
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.Dv NULL
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pointer.
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.Pp
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The
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.Fn execle
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and
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.Fn exect
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functions also specify the environment of the executed process by following
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the
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.Dv NULL
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pointer that terminates the list of arguments in the parameter list
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or the pointer to the argv array with an additional parameter.
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This additional parameter is an array of pointers to null-terminated strings
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and
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.Em must
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be terminated by a
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.Dv NULL
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pointer.
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The other functions take the environment for the new process image from the
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external variable
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.Va environ
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in the current process.
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.Pp
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Some of these functions have special semantics.
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.Pp
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The functions
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.Fn execlp
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and
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.Fn execvp
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will duplicate the actions of the shell in searching for an executable file
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if the specified file name does not contain a slash
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.Dq Li \&/
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character.
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The search path is the path specified in the environment by the
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.Ev PATH
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variable.
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If this variable isn't specified,
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.Va _PATH_DEFPATH
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from
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.In paths.h
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is used instead, its value being:
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.Pa /usr/bin:/bin:/usr/pkg/bin:/usr/local/bin .
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In addition, certain errors are treated specially.
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.Pp
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If permission is denied for a file (the attempted
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.Xr execve 2
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returned
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.Er EACCES ) ,
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these functions will continue searching the rest of
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the search path.
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If no other file is found, however, they will return with the global variable
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.Va errno
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set to
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.Er EACCES .
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.Pp
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If the header of a file isn't recognized (the attempted
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.Xr execve 2
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returned
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.Er ENOEXEC ) ,
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these functions will execute the shell with the path of
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the file as its first argument.
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(If this attempt fails, no further searching is done.)
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.Pp
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If the file is currently busy (the attempted
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.Xr execve 2
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returned
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.Er ETXTBUSY ) ,
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these functions will sleep for several seconds,
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periodically re-attempting to execute the file.
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.Pp
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The function
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.Fn exect
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executes a file with the program tracing facilities enabled (see
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.Xr ptrace 2 ) .
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.Sh RETURN VALUES
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If any of the
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.Nm exec
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functions returns, an error will have occurred.
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The return value is \-1, and the global variable
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.Va errno
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will be set to indicate the error.
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.Sh FILES
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.Bl -tag -width /bin/sh -compact
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.It Pa /bin/sh
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The shell.
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.El
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.Sh ERRORS
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.Fn execl ,
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.Fn execle ,
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.Fn execlp
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and
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.Fn execvp
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may fail and set
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.Va errno
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for any of the errors specified for the library functions
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.Xr execve 2
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and
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.Xr malloc 3 .
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.Pp
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.Fn exect
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and
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.Fn execv
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may fail and set
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.Va errno
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for any of the errors specified for the library function
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.Xr execve 2 .
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.Sh SEE ALSO
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.Xr sh 1 ,
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.Xr execve 2 ,
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.Xr fork 2 ,
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.Xr ptrace 2 ,
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.Xr environ 7 ,
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.Xr script 7
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.Sh COMPATIBILITY
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Historically, the default path for the
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.Fn execlp
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and
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.Fn execvp
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functions was
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.Dq Pa :/bin:/usr/bin .
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This was changed to improve security and behaviour.
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.Pp
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The behavior of
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.Fn execlp
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and
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.Fn execvp
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when errors occur while attempting to execute the file is historic
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practice, but has not traditionally been documented and is not specified
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by the
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.Tn POSIX
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standard.
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.Pp
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Traditionally, the functions
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.Fn execlp
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and
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.Fn execvp
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ignored all errors except for the ones described above and
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.Er ENOMEM
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and
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.Er E2BIG ,
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upon which they returned.
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They now return if any error other than the ones described above occurs.
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.Sh STANDARDS
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.Fn execl ,
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.Fn execv ,
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.Fn execle ,
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.Fn execlp
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and
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.Fn execvp
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conform to
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.St -p1003.1-90 .
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