302 lines
8.3 KiB
Groff
302 lines
8.3 KiB
Groff
.\" $NetBSD: mount_procfs.8,v 1.30 2007/02/02 07:28:03 wiz Exp $
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.\"
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.\" Copyright (c) 1992, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software donated to Berkeley by
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.\" Jan-Simon Pendry.
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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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.\" @(#)mount_procfs.8 8.3 (Berkeley) 6/1/94
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.\"
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.\"
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.Dd February 2, 2007
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.Dt MOUNT_PROCFS 8
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.Os
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.Sh NAME
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.Nm mount_procfs
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.Nd mount the process file system
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.Sh SYNOPSIS
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.Nm
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.Op Fl o Ar options
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.Pa /proc
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.Pa mount_point
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.Sh DESCRIPTION
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The
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.Nm
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command attaches an instance of the process
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namespace to the global filesystem namespace.
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The conventional mount point is
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.Pa /proc .
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The directory specified by
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.Ar mount_point
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is converted to an absolute path before use.
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This command is normally executed by
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.Xr mount 8
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at boot time.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl o
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Options are specified with a
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.Fl o
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flag followed by a comma separated string of options.
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See the
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.Xr mount 8
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man page for possible generic options and their meanings.
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Currently, one procfs-specific option is defined, the
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.Cm linux
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option.
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This option enables a few extra features that are compatible
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with the proc filesystem as implemented in Linux.
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This option can be used if you run Linux binaries that need
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Linux-specific features in the proc filesystem (see also
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.Xr compat_linux 8 ) .
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.El
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.Pp
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The root of the process filesystem
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contains an entry for each active process.
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These processes are visible as a directory whose
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name is the process' pid.
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In addition, the special entries
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.Pa curproc
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and
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.Pa self
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reference the current process.
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The
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.Pa self
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symlink appears for compatibility with the Linux procfs implementation.
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.Pp
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Each directory contains several files.
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.Bl -tag -width status
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.It Pa cmdline
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This file is readonly and returns null-terminated strings
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corresponding to the process' command line arguments.
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For a system or zombie process, this file contains only a string
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with the name of the process.
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.It Pa ctl
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a writeonly file which supports a variety of control operations.
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Control commands are written as strings to the
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.Pa ctl
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file.
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The control commands are:
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.Bl -tag -width detach -compact
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.It attach
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stops the target process and arranges for the sending
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process to become the debug control process.
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.It detach
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continue execution of the target process and
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remove it from control by the debug process.
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.It run
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continue running the target process until
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a signal is delivered, a breakpoint is hit, or the
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target process exits.
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.It step
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single step the target process, with no signal delivery.
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.It wait
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wait for the target process to stop.
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The target process must be stopped before
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any of the run, step, or signal commands are allowed.
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.El
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.Pp
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The string can also be the name of a signal, lower case
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and without the
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.Dv SIG
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prefix,
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in which case that signal is delivered to the process
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(see
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.Xr sigaction 2 ) .
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.It Pa cwd
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A symbolic link that points to the current working directory of the
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process.
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If the target process's current working directory is not available or
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is not at or below the current process's root directory, this link
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will point to
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.Dq / .
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.It Pa fd/#
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File descriptors which can be accessed through the file system.
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See
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.Xr fd 4
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for more information.
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.It Pa file
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A reference to the vnode from which the process text was read.
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This can be used to gain access to the process' symbol table,
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or to start another copy of the process.
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.It Pa map
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A map of the process' virtual memory.
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.It Pa maps
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A map of the process' virtual memory in a form like the
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proc filesystem as implemented in Linux.
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Note that the paths corresponding to file backed mappings will
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not be present unless the kernel was built with the
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NAMECACHE_ENTER_REVERSE option.
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.It Pa mem
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The complete virtual memory image of the process.
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Only those addresses which exist in the process can be accessed.
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Writes to this file modify the process.
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Writes to the text segment normally remain private to the process,
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since the text segment is mapped with MAP_PRIVATE; however, this is
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not guaranteed.
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.It Pa note
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Not implemented.
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.It Pa notepg
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Not implemented.
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.It Pa regs
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Allows read and write access to the process' register set.
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This file contains a binary data structure
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.Dv "struct regs"
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defined in
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.Pa \*[Lt]machine/reg.h\*[Gt] .
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.Pa regs
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can only be written when the process is stopped.
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.It Pa fpregs
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The floating point registers as defined by
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.Dv "struct fpregs"
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in
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.Pa \*[Lt]machine/reg.h\*[Gt] .
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.Pa fpregs
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is only implemented on machines which have distinct general
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purpose and floating point register sets.
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.It Pa root
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A symbolic link that points to the root directory of the process.
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If the target process's root directory is not available or is not at
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or below the current process's root directory, this link will point to
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.Dq / .
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.It Pa status
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The process status.
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This file is readonly and returns a single line containing
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multiple space-separated fields as follows:
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.Pp
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.Bl -bullet -compact
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.It
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command name
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.It
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process id
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.It
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parent process id
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.It
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process group id
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.It
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session id
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.It
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.Ar major,minor
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of the controlling terminal, or
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.Dv -1,-1
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if there is no controlling terminal.
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.It
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a list of process flags:
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.Dv ctty
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if there is a controlling terminal,
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.Dv sldr
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if the process is a session leader,
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.Dv noflags
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if neither of the other two flags are set.
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.It
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the process start time in seconds and microseconds,
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comma separated.
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.It
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the user time in seconds and microseconds,
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comma separated.
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.It
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the system time in seconds and microseconds,
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comma separated.
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.It
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the wait channel message
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.It
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the process credentials consisting of
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the effective user id
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and the list of groups (whose first member
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is the effective group id)
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all comma separated.
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.El
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.El
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.Pp
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In a normal debugging environment,
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where the target is fork/exec'd by the debugger,
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the debugger should fork and the child should stop
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itself (with a self-inflicted
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.Dv SIGSTOP
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for example).
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The parent should issue a
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.Dv wait
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and then an
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.Dv attach
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command via the appropriate
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.Pa ctl
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file.
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The child process will receive a
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.Dv SIGTRAP
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immediately after the call to exec (see
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.Xr execve 2 ) .
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.Sh FILES
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.Bl -tag -width /proc/curproc -compact
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.It Pa /proc/#
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.It Pa /proc/#/cmdline
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.It Pa /proc/#/ctl
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.It Pa /proc/#/cwd
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.It Pa /proc/#/file
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.It Pa /proc/#/fpregs
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.It Pa /proc/#/map
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.It Pa /proc/#/maps
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.It Pa /proc/#/mem
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.It Pa /proc/#/note
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.It Pa /proc/#/notepg
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.It Pa /proc/#/regs
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.It Pa /proc/#/root
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.It Pa /proc/#/status
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.It Pa /proc/curproc
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.It Pa /proc/self
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.El
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.Pp
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If the
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.Cm linux
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mount option is used, the following files are also available:
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.Pp
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.Bl -tag -width /proc/meminfo -compact
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.It Pa /proc/#/exe
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.It Pa /proc/#/stat
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.It Pa /proc/cpuinfo
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.It Pa /proc/device
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.It Pa /proc/meminfo
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.It Pa /proc/mounts
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.It Pa /proc/uptime
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.El
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.Sh SEE ALSO
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.Xr mount 2 ,
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.Xr sigaction 2 ,
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.Xr unmount 2
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.Sh HISTORY
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The
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.Nm
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utility first appeared in
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.Bx 4.4 .
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.Sh BUGS
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This filesystem may not be NFS-exported
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since most of the functionality of
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.Dv procfs
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requires that state be maintained.
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