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
-nosplit The linprocfs was derived from procfs by Pierre Beyssac. This manual page was written by Dag-Erling Smørgrav, based on the procfs(5) manual page by Garrett Wollman.