.\"	$OpenBSD: mount_procfs.8,v 1.24 2011/12/28 19:06:02 guenther Exp $
.\"	$NetBSD: mount_procfs.8,v 1.6 1995/03/18 14:58:10 cgd Exp $
.\"
.\" Copyright (c) 1992, 1993
.\"	The Regents of the University of California.  All rights reserved.
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.\"
.\" This code is derived from software donated to Berkeley by
.\" Jan-Simon Pendry.
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.\"	@(#)mount_procfs.8	8.2 (Berkeley) 3/27/94
.\"
.Dd $Mdocdate: December 28 2011 $
.Dt MOUNT_PROCFS 8
.Os
.Sh NAME
.Nm mount_procfs
.Nd mount the process file system
.Sh SYNOPSIS
.Nm mount_procfs
.Op Fl o Ar options
.Pa /proc
.Pa mount_point
.Sh DESCRIPTION
The
.Nm
command attaches an instance of the process
namespace to the global filesystem namespace.
The conventional mount point is
.Pa /proc .
This command is normally executed by
.Xr mount 8
at boot time.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl o Ar options
Options are specified with a
.Fl o
flag followed by a comma separated string of options.
See the
.Xr mount 8
man page for possible options and their meanings.
The following procfs specific option is also available:
.Bl -tag -width indent
.It linux
Add Linux compatibility links and nodes to procfs.
.El
.El
.Pp
The root of the process filesystem
contains an entry for each active process.
These processes are visible as a directory whose
name is the process's PID.
In addition, the special entry
.Pa curproc
references the current process.
.Pp
Each directory contains several files.
.Bl -tag -width status
.It Pa cmdline
Process command line parameters, separated by NULs.
.It Pa file
A reference to the vnode from which the process text was read.
This can be used to gain access to the process's symbol table,
or to start another copy of the process.
.It Pa mem
The complete virtual memory image of the process.
Only those address which exist in the process can be accessed.
Reads and writes to this file modify the process.
Writes to the text segment remain private to the process.
.It Pa status
The process status.
This file is read-only and returns a single line containing
multiple space-separated fields as follows:
.Pp
.Bl -bullet -compact
.It
Command name.
.It
Process ID.
.It
Parent process ID.
.It
Process group ID.
.It
Session ID.
.It
.Ar major,minor
of the controlling terminal, or
.Dv -1,-1
if there is no controlling terminal.
.It
List of process flags:
.Dv ctty
if there is a controlling terminal,
.Dv sldr
if the process is a session leader, or
.Dv noflags
if neither of the other two flags are set.
.It
Process start time in seconds and microseconds,
comma separated.
.It
User time in seconds and microseconds,
comma separated.
.It
System time in seconds and microseconds,
comma separated.
.It
Wait channel message.
.It
Process credentials consisting of
the effective user ID
and the list of groups (whose first member
is the effective group ID),
all comma separated.
.El
.El
.Pp
Statistics reported by
.Xr df 1
on a procfs filesystem will indicate virtual memory used/available instead of
.Sq disk space ,
and the number of process slots used/allocated instead of
.Sq inodes .
The block size of the filesystem is the system page size.
.Sh FILES
.Bl -tag -width /proc/curproc -compact
.It Pa /proc/#
.It Pa /proc/curproc
.It Pa /proc/curproc/cmdline
.It Pa /proc/curproc/file
.It Pa /proc/curproc/mem
.It Pa /proc/curproc/status
.El
.Sh SEE ALSO
.Xr mount 2 ,
.Xr fstab 5 ,
.Xr mount 8 ,
.Xr umount 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Bx 4.4 .
.Sh CAVEATS
This filesystem may not be NFS-exported
since most of the functionality of
.Dv procfs
requires that state be maintained.