.\" Written by Garrett Wollman
.\" This file is in the public domain.
.\"
.Dd November 13, 2019
.Dt LINPROCFS 5
.Os
.Sh NAME
.Nm linprocfs
.Nd Linux process file system
.Sh SYNOPSIS
.Bd -literal
linproc		/compat/linux/proc	linprocfs	rw 0 0
.Ed
.Sh DESCRIPTION
The Linux process file system, or
.Nm ,
emulates a subset of Linux' process file system and is required for
the complete operation of some Linux binaries.
.Pp
The
.Nm
provides a two-level view of process space.
At the highest level, processes themselves are named, according to
their process ids in decimal, with no leading zeros.
There is also a special node called
.Pa self
which always refers to the process making the lookup request.
.Pp
Each node is a directory containing several files:
.Bl -tag -width status
.It Pa exe
A reference to the vnode from which the process text was read.
This can be used to gain access to the process' symbol table,
or to start another copy of the process.
.It Pa mem
The complete virtual memory image of the process.
Only those addresses 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.
.El
.Pp
Each node is owned by the process's user, and belongs to that user's
primary group, except for the
.Pa mem
node, which belongs to the
.Li kmem
group.
.Sh FILES
.Bl -tag -width /compat/linux/proc/self/XXXXXXX -compact
.It Pa /compat/linux/proc
The normal mount point for the
.Nm .
.It Pa /compat/linux/proc/cpuinfo
CPU vendor and model information in human-readable form.
.It Pa /compat/linux/proc/meminfo
System memory information in human-readable form.
.It Pa /compat/linux/proc/pid
A directory containing process information for process
.Pa pid .
.It Pa /compat/linux/proc/self
A directory containing process information for the current process.
.It Pa /compat/linux/proc/self/exe
The executable image for the current process.
.It Pa /compat/linux/proc/self/mem
The complete virtual address space of the current process.
.El
.Sh EXAMPLES
To mount a
.Nm
file system on
.Pa /compat/linux/proc :
.Pp
.Dl "mount -t linprocfs linproc /compat/linux/proc"
.Sh SEE ALSO
.Xr mount 2 ,
.Xr unmount 2 ,
.Xr linux 4 ,
.Xr procfs 5 ,
.Xr pseudofs 9
.Sh HISTORY
The
.Nm
first appeared in
.Fx 4.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
was derived from
.Nm procfs
by
.An Pierre Beyssac .
This manual page was written by
.An Dag-Erling Sm\(/orgrav ,
based on the
.Xr procfs 5
manual page by
.An Garrett Wollman .