LINPROCFS(4) FreeBSD Kernel Interfaces Manual LINPROCFS(4)
NAME
linprocfs - Linux process file system
SYNOPSIS
linprocfs /compat/linux/proc linprocfs rw 0 0
DESCRIPTION
The Linux process file system, or linprocfs, emulates a subset of Linux'
process file system and is required for the complete operation of some
Linux binaries.
The linprocfs 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 self
which always refers to the process making the lookup request.
Each process node is a directory containing several files:
auxv The auxiliary vector passed to the program.
cmdline The command line used to execute the process.
cwd A symbolic link pointing to the current work directory of
the process.
environ The list of environment variables and values of the
process. Every variable and pair value is separated from
the next by a NULL byte.
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.
limits The soft and hard limits for the process along with the
units used.
maps Memory map of the process.
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.
mountinfo Information about mount points.
mounts Similar to the above.
oom_score_adj Score adjustment for the Out Of Memory killer.
root Symbolic link to the root directory for this process.
stat Process statistics. It includes user, nice, system, idle,
iowait, irq, softirq, steal, guest and guest_nice.
statm Process size statistics. It includes total program size,
resident set size, number of resident shared pages
(unused), text size, library size (unused), data + stack
and dirty pages (unused).
status Process statistics in human readable form. It includes
process name, state, PID, etc.
task Dummy directory to avoid problems in specific software
such as Chromium.
Each node is owned by the process's user, and belongs to that user's
primary group, except for the mem node, which belongs to the kmem group.
FILES
/compat/linux/proc The normal mount point for linprocfs.
/compat/linux/proc/cmdline Contains the path of the kernel image
used to boot the system.
/compat/linux/proc/cpuinfo CPU vendor and model information in
human-readable form.
/compat/linux/proc/devices List of character and block devices. The
later is usually empty on FreeBSD.
/compat/linux/proc/filesystems List of supported filesystems. For
pseudo filesystems, the first column
contains nodev.
/compat/linux/proc/meminfo System memory information in human-
readable form.
/compat/linux/proc/modules Loaded kernel modules. Empty for now.
/compat/linux/proc/mounts Devices corresponding mount points.
/compat/linux/proc/mtab Same as above.
/compat/linux/proc/partitions Partition information including major and
minor numbers, number of blocks and name.
The rest of the fields are set to zero.
/compat/linux/proc/stat System statistics. For each cpu it
includes at most user time, nice time,
system time and idle time, iowait (time
waiting for I/O to complete), times
serving irqs and softirq, steal, guest
and guest_nice times that represent times
spent in different modes in a virtualized
environment. The last columns are set to
zero. This file also contains brief
statistics for disks, context switches
and more.
/compat/linux/proc/swap Information about the swap device if any.
/compat/linux/proc/uptime Time since the last boot and time spent
in idle state.
/compat/linux/proc/version Version of the emulated linux system.
/compat/linux/proc/<pid> A directory containing process
information for process pid.
/compat/linux/proc/self A symlink to a directory containing
process information for the current
process.
EXAMPLES
To mount a linprocfs file system on /compat/linux/proc:
mount -t linprocfs linprocfs /compat/linux/proc
SEE ALSO
mount(2), unmount(2), auxv(3), linux(4), procfs(5), pseudofs(9)
HISTORY
The linprocfs first appeared in FreeBSD 4.0.
AUTHORS
The linprocfs was derived from procfs by Pierre Beyssac. This manual
page was written by Dag-Erling Smorgrav, based on the procfs(5) manual
page by Garrett Wollman.
FreeBSD 15.1-STABLE-HBSD December 26, 2025 LINPROCFS(4)