fca6393ad4
link points to the process's current working directory, and the root link points to the process's root directory. What else would you expect? For directories that are out of reach (caller is in a chroot, target process is in a different chroot, etc), the links point to "/" instead.
291 lines
8.1 KiB
Groff
291 lines
8.1 KiB
Groff
.\" $NetBSD: mount_procfs.8,v 1.27 2005/10/01 03:17:37 atatat 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 June 1, 1994
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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 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/#/file
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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/#/fpregs
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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/cpuinfo
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.It Pa /proc/meminfo
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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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