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PROC(5)			   Linux Programmer's Manual		       PROC(5)

NAME
       proc - process information pseudo-filesystem

DESCRIPTION
       The  proc filesystem is a pseudo-filesystem which provides an interface
       to kernel data structures.  It is commonly mounted at /proc.   Most  of
       it is read-only, but some files allow kernel variables to be changed.

       The  following  list  describes many of the files and directories under
       the /proc hierarchy.

       /proc/[pid]
	      There is a numerical subdirectory for each running process;  the
	      subdirectory is named by the process ID.	Each such subdirectory
	      contains the following pseudo-files and directories.

       /proc/[pid]/auxv (since 2.6.0-test7)
	      This contains the contents of the	 ELF  interpreter  information
	      passed  to the process at exec time.  The format is one unsigned
	      long ID plus one unsigned long value for each entry.   The  last
	      entry contains two zeros.

       /proc/[pid]/cgroup (since Linux 2.6.24)
	      This  file  describes  control  groups to which the process/task
	      belongs.	For each cgroup hierarchy there is one entry  contain‐
	      ing colon-separated fields of the form:

		  5:cpuacct,cpu,cpuset:/daemons

	      The colon-separated fields are, from left to right:

		  1. hierarchy ID number

		  2. set of subsystems bound to the hierarchy

		  3. control  group  in	 the  hierarchy	 to  which the process
		     belongs

	      This file is present only if the CONFIG_CGROUPS kernel  configu‐
	      ration option is enabled.

       /proc/[pid]/clear_refs (since Linux 2.6.22)

	      This  is	a  write-only  file,  writable	only  by  owner of the
	      process.

	      The following values may be written to the file:

	      1 (since Linux 2.6.22)
		     Reset the PG_Referenced and ACCESSED/YOUNG bits  for  all
		     the  pages	 associated  with the process.	(Before kernel
		     2.6.32, writing any nonzero value to this file  had  this
		     effect.)

	      2 (since Linux 2.6.32)
		     Reset  the	 PG_Referenced and ACCESSED/YOUNG bits for all
		     anonymous pages associated with the process.

	      3 (since Linux 2.6.32)
		     Reset the PG_Referenced and ACCESSED/YOUNG bits  for  all
		     file-mapped pages associated with the process.

	      Clearing	the  PG_Referenced  and ACCESSED/YOUNG bits provides a
	      method to measure approximately how much	memory	a  process  is
	      using.   One  first  inspects  the  values  in the "Referenced:"
	      fields for the VMAs shown in /proc/[pid]/smaps to get an idea of
	      the  memory  footprint  of  the  process.	  One  then clears the
	      PG_Referenced and ACCESSED/YOUNG bits and, after	some  measured
	      time  interval,  once  again  inspects the values in the "Refer‐
	      enced:" fields to get an idea of the change in memory  footprint
	      of  the  process during the measured interval.  If one is inter‐
	      ested only in inspecting the selected mapping  types,  then  the
	      value 2 or 3 can be used instead of 1.

	      A further value can be written to affect a different bit:

	      4 (since Linux 3.11)
		     Clear  the	 soft-dirty  bit  for all the pages associated
		     with the process.	This  is  used	(in  conjunction  with
		     /proc/[pid]/pagemap) by the check-point restore system to
		     discover which pages of a process have been dirtied since
		     the file /proc/[pid]/clear_refs was written to.

	      Writing  any  value  to  /proc/[pid]/clear_refs other than those
	      listed above has no effect.

	      The /proc/[pid]/clear_refs file is  present  only	 if  the  CON‐
	      FIG_PROC_PAGE_MONITOR kernel configuration option is enabled.

       /proc/[pid]/cmdline
	      This holds the complete command line for the process, unless the
	      process is a zombie.  In the latter case, there  is  nothing  in
	      this  file:  that	 is, a read on this file will return 0 charac‐
	      ters.  The command-line arguments appear in this file as	a  set
	      of  strings  separated by null bytes ('\0'), with a further null
	      byte after the last string.

       /proc/[pid]/coredump_filter (since kernel 2.6.23)
	      See core(5).

       /proc/[pid]/cpuset (since kernel 2.6.12)
	      See cpuset(7).

       /proc/[pid]/cwd
	      This is a symbolic link to the current working directory of  the
	      process.	 To  find out the current working directory of process
	      20, for instance, you can do this:

		  $ cd /proc/20/cwd; /bin/pwd

	      Note that the pwd command is often a shell built-in,  and	 might
	      not work properly.  In bash(1), you may use pwd -P.

	      In  a  multithreaded process, the contents of this symbolic link
	      are not available if the	main  thread  has  already  terminated
	      (typically by calling pthread_exit(3)).

       /proc/[pid]/environ
	      This file contains the environment for the process.  The entries
	      are separated by null bytes ('\0'), and there may be a null byte
	      at  the  end.   Thus, to print out the environment of process 1,
	      you would do:

		  $ strings /proc/1/environ

       /proc/[pid]/exe
	      Under Linux 2.2 and later, this file is a symbolic link contain‐
	      ing  the actual pathname of the executed command.	 This symbolic
	      link can be dereferenced normally; attempting to	open  it  will
	      open  the	 executable.  You can even type /proc/[pid]/exe to run
	      another copy of the same executable as is being run  by  process
	      [pid].   In  a  multithreaded process, the contents of this sym‐
	      bolic link are not available if the main thread has already ter‐
	      minated (typically by calling pthread_exit(3)).

	      Under  Linux 2.0 and earlier /proc/[pid]/exe is a pointer to the
	      binary which was executed, and appears as a  symbolic  link.   A
	      readlink(2)  call	 on this file under Linux 2.0 returns a string
	      in the format:

		  [device]:inode

	      For example, [0301]:1502 would be inode 1502 on device major  03
	      (IDE,  MFM,  etc. drives) minor 01 (first partition on the first
	      drive).

	      find(1) with the -inum option can be used to locate the file.

       /proc/[pid]/fd/
	      This is a subdirectory containing one entry for each file	 which
	      the process has open, named by its file descriptor, and which is
	      a symbolic link to the actual file.  Thus, 0 is standard	input,
	      1 standard output, 2 standard error, and so on.

	      For  file descriptors for pipes and sockets, the entries will be
	      symbolic links whose content is the file type with the inode.  A
	      readlink(2) call on this file returns a string in the format:

		  type:[inode]

	      For  example, socket:[2248868] will be a socket and its inode is
	      2248868.	For sockets, that inode	 can  be  used	to  find  more
	      information in one of the files under /proc/net/.

	      For  file	 descriptors  that  have no corresponding inode (e.g.,
	      file descriptors produced by epoll_create(2),  eventfd(2),  ino‐
	      tify_init(2),  signalfd(2), and timerfd(2)), the entry will be a
	      symbolic link with contents of the form

		  anon_inode:<file-type>

	      In some cases, the file-type is surrounded by square brackets.

	      For example, an epoll file descriptor will have a symbolic  link
	      whose content is the string anon_inode:[eventpoll].

	      In  a  multithreaded process, the contents of this directory are
	      not available if the main thread has already  terminated	(typi‐
	      cally by calling pthread_exit(3)).

	      Programs	that  will take a filename as a command-line argument,
	      but will not take input from standard input if  no  argument  is
	      supplied,	 or that write to a file named as a command-line argu‐
	      ment, but will not send their output to standard	output	if  no
	      argument	is  supplied, can nevertheless be made to use standard
	      input or standard out using /proc/[pid]/fd.  For example, assum‐
	      ing  that -i is the flag designating an input file and -o is the
	      flag designating an output file:

		  $ foobar -i /proc/self/fd/0 -o /proc/self/fd/1 ...

	      and you have a working filter.

	      /proc/self/fd/N is approximately the same as /dev/fd/N  in  some
	      UNIX and UNIX-like systems.  Most Linux MAKEDEV scripts symboli‐
	      cally link /dev/fd to /proc/self/fd, in fact.

	      Most systems provide symbolic links /dev/stdin, /dev/stdout, and
	      /dev/stderr, which respectively link to the files 0, 1, and 2 in
	      /proc/self/fd.  Thus the example command above could be  written
	      as:

		  $ foobar -i /dev/stdin -o /dev/stdout ...

       /proc/[pid]/fdinfo/ (since kernel 2.6.22)
	      This  is a subdirectory containing one entry for each file which
	      the process has open, named by its file  descriptor.   The  con‐
	      tents  of	 each file can be read to obtain information about the
	      corresponding file descriptor, for example:

		  $ cat /proc/12015/fdinfo/4
		  pos:	  1000
		  flags:  01002002

	      The pos field is a decimal number showing the current file  off‐
	      set.   The flags field is an octal number that displays the file
	      access mode and file status flags (see open(2)).

	      The files in this directory are readable only by	the  owner  of
	      the process.

       /proc/[pid]/io (since kernel 2.6.20)
	      This file contains I/O statistics for the process, for example:

		  # cat /proc/3828/io
		  rchar: 323934931
		  wchar: 323929600
		  syscr: 632687
		  syscw: 632675
		  read_bytes: 0
		  write_bytes: 323932160
		  cancelled_write_bytes: 0

	      The fields are as follows:

	      rchar: characters read
		     The number of bytes which this task has caused to be read
		     from storage.  This is simply the sum of bytes which this
		     process  passed  to read(2) and similar system calls.  It
		     includes things such as terminal I/O and is unaffected by
		     whether or not actual physical disk I/O was required (the
		     read might have been satisfied from pagecache).

	      wchar: characters written
		     The number of bytes which this task has caused, or	 shall
		     cause  to be written to disk.  Similar caveats apply here
		     as with rchar.

	      syscr: read syscalls
		     Attempt to count the number of read  I/O  operations—that
		     is, system calls such as read(2) and pread(2).

	      syscw: write syscalls
		     Attempt  to count the number of write I/O operations—that
		     is, system calls such as write(2) and pwrite(2).

	      read_bytes: bytes read
		     Attempt to count the number of bytes which	 this  process
		     really  did  cause	 to be fetched from the storage layer.
		     This is accurate for block-backed filesystems.

	      write_bytes: bytes written
		     Attempt to count the number of bytes which	 this  process
		     caused to be sent to the storage layer.

	      cancelled_write_bytes:
		     The big inaccuracy here is truncate.  If a process writes
		     1MB to a file and then deletes the file, it will in  fact
		     perform  no writeout.  But it will have been accounted as
		     having caused 1MB of write.  In other words:  this	 field
		     represents	 the number of bytes which this process caused
		     to not happen, by truncating pagecache.  A task can cause
		     "negative"	 I/O  too.   If this task truncates some dirty
		     pagecache, some I/O which another task has been accounted
		     for (in its write_bytes) will not be happening.

	      Note:  In	 the  current implementation, things are a bit racy on
	      32-bit systems: if process A reads  process  B's	/proc/[pid]/io
	      while  process  B	 is  updating  one  of	these 64-bit counters,
	      process A could see an intermediate result.

       /proc/[pid]/limits (since kernel 2.6.24)
	      This file displays the soft limit, hard limit, and units of mea‐
	      surement	for  each  of the process's resource limits (see getr‐
	      limit(2)).  Up to and including Linux 2.6.35, this file is  pro‐
	      tected  to  allow	 reading  only by the real UID of the process.
	      Since Linux 2.6.36, this file is readable by all	users  on  the
	      system.

       /proc/[pid]/map_files/ (since kernel 3.3)
	      This  subdirectory  contains  entries  corresponding  to memory-
	      mapped files (see mmap(2)).  Entries are named by memory	region
	      start  and  end address pair (expressed as hexadecimal numbers),
	      and are symbolic links to the mapped files themselves.  Here  is
	      an example, with the output wrapped and reformatted to fit on an
	      80-column display:

		  $ ls -l /proc/self/map_files/
		  lr--------. 1 root root 64 Apr 16 21:31
			      3252e00000-3252e20000 -> /usr/lib64/ld-2.15.so
		  ...

	      Although these entries are present for memory regions that  were
	      mapped  with  the MAP_FILE flag, the way anonymous shared memory
	      (regions created with the MAP_ANON | MAP_SHARED flags) is imple‐
	      mented  in  Linux	 means	that  such regions also appear on this
	      directory.  Here is an example where  the	 target	 file  is  the
	      deleted /dev/zero one:

		  lrw-------. 1 root root 64 Apr 16 21:33
			      7fc075d2f000-7fc075e6f000 -> /dev/zero (deleted)

	      This  directory  appears	only  if the CONFIG_CHECKPOINT_RESTORE
	      kernel configuration option is enabled.

       /proc/[pid]/maps
	      A file containing the currently mapped memory regions and	 their
	      access  permissions.   See  mmap(2) for some further information
	      about memory mappings.

	      The format of the file is:

       address		 perms offset  dev   inode	 pathname
       00400000-00452000 r-xp 00000000 08:02 173521	 /usr/bin/dbus-daemon
       00651000-00652000 r--p 00051000 08:02 173521	 /usr/bin/dbus-daemon
       00652000-00655000 rw-p 00052000 08:02 173521	 /usr/bin/dbus-daemon
       00e03000-00e24000 rw-p 00000000 00:00 0		 [heap]
       00e24000-011f7000 rw-p 00000000 00:00 0		 [heap]
       ...
       35b1800000-35b1820000 r-xp 00000000 08:02 135522	 /usr/lib64/ld-2.15.so
       35b1a1f000-35b1a20000 r--p 0001f000 08:02 135522	 /usr/lib64/ld-2.15.so
       35b1a20000-35b1a21000 rw-p 00020000 08:02 135522	 /usr/lib64/ld-2.15.so
       35b1a21000-35b1a22000 rw-p 00000000 00:00 0
       35b1c00000-35b1dac000 r-xp 00000000 08:02 135870	 /usr/lib64/libc-2.15.so
       35b1dac000-35b1fac000 ---p 001ac000 08:02 135870	 /usr/lib64/libc-2.15.so
       35b1fac000-35b1fb0000 r--p 001ac000 08:02 135870	 /usr/lib64/libc-2.15.so
       35b1fb0000-35b1fb2000 rw-p 001b0000 08:02 135870	 /usr/lib64/libc-2.15.so
       ...
       f2c6ff8c000-7f2c7078c000 rw-p 00000000 00:00 0	 [stack:986]
       ...
       7fffb2c0d000-7fffb2c2e000 rw-p 00000000 00:00 0	 [stack]
       7fffb2d48000-7fffb2d49000 r-xp 00000000 00:00 0	 [vdso]

	      The address field is the address space in the process  that  the
	      mapping occupies.	 The perms field is a set of permissions:

		   r = read
		   w = write
		   x = execute
		   s = shared
		   p = private (copy on write)

	      The  offset  field  is the offset into the file/whatever; dev is
	      the device (major:minor); inode is the inode on that device.   0
	      indicates that no inode is associated with the memory region, as
	      would be the case with BSS (uninitialized data).

	      The pathname field will usually be the file that is backing  the
	      mapping.	For ELF files, you can easily coordinate with the off‐
	      set field by looking at the Offset  field	 in  the  ELF  program
	      headers (readelf -l).

	      There are additional helpful pseudo-paths:

		   [stack]
			  The  initial	process's  (also  known	 as  the  main
			  thread's) stack.

		   [stack:<tid>] (since Linux 3.4)
			  A thread's stack (where the <tid> is a  thread  ID).
			  It corresponds to the /proc/[pid]/task/[tid]/ path.

		   [vdso] The virtual dynamically linked shared object.

		   [heap] The process's heap.

	      If  the pathname field is blank, this is an anonymous mapping as
	      obtained via the mmap(2) function.  There	 is  no	 easy  way  to
	      coordinate  this back to a process's source, short of running it
	      through gdb(1), strace(1), or similar.

	      Under Linux 2.0 there is no field giving pathname.

       /proc/[pid]/mem
	      This file can be used to access the pages of a process's	memory
	      through open(2), read(2), and lseek(2).

       /proc/[pid]/mountinfo (since Linux 2.6.26)
	      This  file contains information about mount points.  It contains
	      lines of the form:

	      36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
	      (1)(2)(3)	  (4)	(5)	 (6)	  (7)	(8) (9)	  (10)	       (11)

	      The numbers in  parentheses  are	labels	for  the  descriptions
	      below:

	      (1)  mount  ID:  unique  identifier  of the mount (may be reused
		   after umount(2)).

	      (2)  parent ID: ID of parent mount (or of self for  the  top  of
		   the mount tree).

	      (3)  major:minor:	 value	of st_dev for files on filesystem (see
		   stat(2)).

	      (4)  root: root of the mount within the filesystem.

	      (5)  mount point: mount point relative to the process's root.

	      (6)  mount options: per-mount options.

	      (7)  optional  fields:  zero  or	more  fields   of   the	  form
		   "tag[:value]".

	      (8)  separator: marks the end of the optional fields.

	      (9)  filesystem type: name of filesystem in the form "type[.sub‐
		   type]".

	      (10) mount source: filesystem-specific information or "none".

	      (11) super options: per-superblock options.

	      Parsers should ignore all unrecognized  optional	fields.	  Cur‐
	      rently the possible optional fields are:

		   shared:X	     mount is shared in peer group X

		   master:X	     mount is slave to peer group X

		   propagate_from:X  mount  is	slave and receives propagation
				     from peer group X (*)

		   unbindable	     mount is unbindable

	      (*) X is the closest dominant peer  group	 under	the  process's
	      root.  If X is the immediate master of the mount, or if there is
	      no dominant peer group under the same root, then only the	 "mas‐
	      ter:X" field is present and not the "propagate_from:X" field.

	      For  more	 information  on  mount	 propagation  see:  Documenta‐
	      tion/filesystems/sharedsubtree.txt in the	 Linux	kernel	source
	      tree.

       /proc/[pid]/mounts (since Linux 2.4.19)
	      This  is	a list of all the filesystems currently mounted in the
	      process's mount namespace.  The format of	 this  file  is	 docu‐
	      mented  in  fstab(5).  Since kernel version 2.6.15, this file is
	      pollable: after opening the file for reading, a change  in  this
	      file  (i.e.,  a filesystem mount or unmount) causes select(2) to
	      mark  the	 file  descriptor  as  readable,   and	 poll(2)   and
	      epoll_wait(2) mark the file as having an error condition.

       /proc/[pid]/mountstats (since Linux 2.6.17)
	      This  file exports information (statistics, configuration infor‐
	      mation) about the mount points  in  the  process's  name	space.
	      Lines in this file have the form:

	      device /dev/sda7 mounted on /home with fstype ext3 [statistics]
	      (	      1	     )		  ( 2 )		    (3 ) (4)

	      The fields in each line are:

	      (1)  The	name  of the mounted device (or "nodevice" if there is
		   no corresponding device).

	      (2)  The mount point within the filesystem tree.

	      (3)  The filesystem type.

	      (4)  Optional statistics and  configuration  information.	  Cur‐
		   rently  (as	at  Linux 2.6.26), only NFS filesystems export
		   information via this field.

	      This file is readable only by the owner of the process.

       /proc/[pid]/ns/ (since Linux 3.0)
	      This is a subdirectory containing one entry for  each  namespace
	      that  supports  being  manipulated by setns(2).  For information
	      about namespaces, see clone(2).

       /proc/[pid]/ns/ipc (since Linux 3.0)
	      Bind mounting this file (see mount(2)) to somewhere else in  the
	      filesystem  keeps	 the IPC namespace of the process specified by
	      pid alive even if all processes currently in the namespace  ter‐
	      minate.

	      Opening this file returns a file handle for the IPC namespace of
	      the process specified by pid.  As long as this  file  descriptor
	      remains  open,  the IPC namespace will remain alive, even if all
	      processes in the namespace terminate.  The file  descriptor  can
	      be passed to setns(2).

       /proc/[pid]/ns/net (since Linux 3.0)
	      Bind  mounting this file (see mount(2)) to somewhere else in the
	      filesystem keeps the network namespace of the process  specified
	      by pid alive even if all processes in the namespace terminate.

	      Opening  this  file returns a file handle for the network names‐
	      pace of the process specified by pid.   As  long	as  this  file
	      descriptor  remains  open,  the  network	namespace  will remain
	      alive, even if all processes in the  namespace  terminate.   The
	      file descriptor can be passed to setns(2).

       /proc/[pid]/ns/uts (since Linux 3.0)
	      Bind  mounting this file (see mount(2)) to somewhere else in the
	      filesystem keeps the UTS namespace of the process	 specified  by
	      pid  alive even if all processes currently in the namespace ter‐
	      minate.

	      Opening this file returns a file handle for the UTS namespace of
	      the  process  specified by pid.  As long as this file descriptor
	      remains open, the UTS namespace will remain alive, even  if  all
	      processes	 in  the namespace terminate.  The file descriptor can
	      be passed to setns(2).

       /proc/[pid]/numa_maps (since Linux 2.6.14)
	      See numa(7).

       /proc/[pid]/oom_adj (since Linux 2.6.11)
	      This file can be used to adjust the score used to	 select	 which
	      process  should  be  killed in an out-of-memory (OOM) situation.
	      The kernel uses this value for  a	 bit-shift  operation  of  the
	      process's	 oom_score value: valid values are in the range -16 to
	      +15, plus the special  value  -17,  which	 disables  OOM-killing
	      altogether  for  this  process.	A positive score increases the
	      likelihood of this process being killed  by  the	OOM-killer;  a
	      negative score decreases the likelihood.

	      The default value for this file is 0; a new process inherits its
	      parent's	oom_adj	 setting.   A  process	must   be   privileged
	      (CAP_SYS_RESOURCE) to update this file.

	      Since  Linux  2.6.36, use of this file is deprecated in favor of
	      /proc/[pid]/oom_score_adj.

       /proc/[pid]/oom_score (since Linux 2.6.11)
	      This file displays the current score that the  kernel  gives  to
	      this process for the purpose of selecting a process for the OOM-
	      killer.  A higher score means that the process is more likely to
	      be  selected by the OOM-killer.  The basis for this score is the
	      amount of memory used by the  process,  with  increases  (+)  or
	      decreases (-) for factors including:

	      * whether	 the  process  creates a lot of children using fork(2)
		(+);

	      * whether the process has been running a long time, or has  used
		a lot of CPU time (-);

	      * whether the process has a low nice value (i.e., > 0) (+);

	      * whether the process is privileged (-); and

	      * whether the process is making direct hardware access (-).

	      The  oom_score  also  reflects  the  adjustment specified by the
	      oom_score_adj or oom_adj setting for the process.

       /proc/[pid]/oom_score_adj (since Linux 2.6.36)
	      This file can be used to adjust the badness  heuristic  used  to
	      select which process gets killed in out-of-memory conditions.

	      The  badness  heuristic  assigns	a value to each candidate task
	      ranging from 0 (never kill) to 1000 (always kill)	 to  determine
	      which  process  is targeted.  The units are roughly a proportion
	      along that range of allowed  memory  the	process	 may  allocate
	      from, based on an estimation of its current memory and swap use.
	      For example, if a task is using all allowed memory, its  badness
	      score  will be 1000.  If it is using half of its allowed memory,
	      its score will be 500.

	      There is an additional factor included  in  the  badness	score:
	      root processes are given 3% extra memory over other tasks.

	      The  amount  of "allowed" memory depends on the context in which
	      the OOM-killer was called.  If it is due to the memory  assigned
	      to  the  allocating  task's  cpuset being exhausted, the allowed
	      memory represents the set of mems assigned to that  cpuset  (see
	      cpuset(7)).   If	it  is	due  to	 a  mempolicy's	 node(s) being
	      exhausted, the allowed memory represents the  set	 of  mempolicy
	      nodes.   If  it  is  due to a memory limit (or swap limit) being
	      reached, the allowed memory is that configured limit.   Finally,
	      if  it  is  due  to  the	entire system being out of memory, the
	      allowed memory represents all allocatable resources.

	      The value of oom_score_adj is added to the badness score	before
	      it  is  used to determine which task to kill.  Acceptable values
	      range    from	-1000	  (OOM_SCORE_ADJ_MIN)	  to	 +1000
	      (OOM_SCORE_ADJ_MAX).   This  allows  user	 space	to control the
	      preference for OOM-killing, ranging  from	 always	 preferring  a
	      certain  task  or completely disabling it from OOM-killing.  The
	      lowest possible value, -1000, is equivalent  to  disabling  OOM-
	      killing  entirely	 for  that task, since it will always report a
	      badness score of 0.

	      Consequently, it is very simple for user	space  to  define  the
	      amount   of  memory  to  consider	 for  each  task.   Setting  a
	      oom_score_adj value of +500, for example, is roughly  equivalent
	      to  allowing  the	 remainder  of	tasks sharing the same system,
	      cpuset, mempolicy, or memory  controller	resources  to  use  at
	      least  50%  more	memory.	  A  value of -500, on the other hand,
	      would be roughly equivalent to discounting  50%  of  the	task's
	      allowed  memory  from  being  considered	as scoring against the
	      task.

	      For    backward	 compatibility	  with	  previous    kernels,
	      /proc/[pid]/oom_adj can still be used to tune the badness score.
	      Its value is scaled linearly with oom_score_adj.

	      Writing to /proc/[pid]/oom_score_adj or /proc/[pid]/oom_adj will
	      change the other with its scaled value.

       /proc/[pid]/root
	      UNIX  and	 Linux	support	 the idea of a per-process root of the
	      filesystem, set by the chroot(2) system call.  This  file	 is  a
	      symbolic	link  that points to the process's root directory, and
	      behaves in the same way as exe, and fd/*.

	      In a multithreaded process, the contents of this	symbolic  link
	      are  not	available  if  the  main thread has already terminated
	      (typically by calling pthread_exit(3)).

       /proc/[pid]/smaps (since Linux 2.6.14)
	      This file shows memory consumption for  each  of	the  process's
	      mappings.	  For  each mapping there is a series of lines such as
	      the following:

		  00400000-0048a000 r-xp 00000000 fd:03 960637	     /bin/bash
		  Size:		       552 kB
		  Rss:		       460 kB
		  Pss:		       100 kB
		  Shared_Clean:	       452 kB
		  Shared_Dirty:		 0 kB
		  Private_Clean:	 8 kB
		  Private_Dirty:	 0 kB
		  Referenced:	       460 kB
		  Anonymous:		 0 kB
		  AnonHugePages:	 0 kB
		  Swap:			 0 kB
		  KernelPageSize:	 4 kB
		  MMUPageSize:		 4 kB
		  Locked:		 0 kB

	      The first of these lines shows the same information as  is  dis‐
	      played for the mapping in /proc/[pid]/maps.  The remaining lines
	      show the size of the mapping, the amount of the mapping that  is
	      currently	 resident  in  RAM  ("Rss"), the process' proportional
	      share of this mapping ("Pss"), the number	 of  clean  and	 dirty
	      shared  pages  in the mapping, and the number of clean and dirty
	      private pages in the mapping.  "Referenced" indicates the amount
	      of  memory  currently marked as referenced or accessed.  "Anony‐
	      mous" shows the amount of memory that does  not  belong  to  any
	      file.   "Swap"  shows how much would-be-anonymous memory is also
	      used, but out on swap.

	      The "KernelPageSize" entry  is the page size used by the	kernel
	      to  back	a  VMA.	  This matches the size used by the MMU in the
	      majority of cases.  However, one counter-example occurs on PPC64
	      kernels whereby a kernel using 64K as a base page size may still
	      use 4K pages for the MMU on older processors.   To  distinguish,
	      this  patch  reports  "MMUPageSize" as the page size used by the
	      MMU.

	      The "Locked" indicates whether the mapping is locked  in	memory
	      or not.

	      "VmFlags"	 field represents the kernel flags associated with the
	      particular virtual memory area in	 two  letter  encoded  manner.
	      The codes are the following:

		  rd  - readable
		  wr  - writable
		  ex  - executable
		  sh  - shared
		  mr  - may read
		  mw  - may write
		  me  - may execute
		  ms  - may share
		  gd  - stack segment growns down
		  pf  - pure PFN range
		  dw  - disabled write to the mapped file
		  lo  - pages are locked in memory
		  io  - memory mapped I/O area
		  sr  - sequential read advise provided
		  rr  - random read advise provided
		  dc  - do not copy area on fork
		  de  - do not expand area on remapping
		  ac  - area is accountable
		  nr  - swap space is not reserved for the area
		  ht  - area uses huge tlb pages
		  nl  - non-linear mapping
		  ar  - architecture specific flag
		  dd  - do not include area into core dump
		  sd  - soft-dirty flag
		  mm  - mixed map area
		  hg  - huge page advise flag
		  nh  - no-huge page advise flag
		  mg  - mergable advise flag

	      The   /proc/[pid]/smaps	file  is  present  only	 if  the  CON‐
	      FIG_PROC_PAGE_MONITOR kernel configuration option is enabled.

       /proc/[pid]/stack (since Linux 2.6.29)
	      This file provides a symbolic trace of  the  function  calls  in
	      this  process's kernel stack.  This file is provided only if the
	      kernel  was  built  with	the  CONFIG_STACKTRACE	 configuration
	      option.

       /proc/[pid]/stat
	      Status  information  about  the process.	This is used by ps(1).
	      It is defined in /usr/src/linux/fs/proc/array.c.

	      The fields, in order, with their proper scanf(3)	format	speci‐
	      fiers, are:

	      pid %d	  (1) The process ID.

	      comm %s	  (2)  The filename of the executable, in parentheses.
			  This is visible whether or  not  the	executable  is
			  swapped out.

	      state %c	  (3)  One  character from the string "RSDZTW" where R
			  is running, S is sleeping in an interruptible	 wait,
			  D  is	 waiting  in  uninterruptible disk sleep, Z is
			  zombie, T is traced or stopped (on a signal), and  W
			  is paging.

	      ppid %d	  (4) The PID of the parent.

	      pgrp %d	  (5) The process group ID of the process.

	      session %d  (6) The session ID of the process.

	      tty_nr %d	  (7)  The  controlling terminal of the process.  (The
			  minor device number is contained in the  combination
			  of bits 31 to 20 and 7 to 0; the major device number
			  is in bits 15 to 8.)

	      tpgid %d	  (8) The ID of the foreground process	group  of  the
			  controlling terminal of the process.

	      flags %u (%lu before Linux 2.6.22)
			  (9)  The  kernel flags word of the process.  For bit
			  meanings, see the PF_* defines in the	 Linux	kernel
			  source  file	include/linux/sched.h.	Details depend
			  on the kernel version.

	      minflt %lu  (10) The number of minor faults the process has made
			  which	 have  not required loading a memory page from
			  disk.

	      cminflt %lu (11) The number of minor faults that	the  process's
			  waited-for children have made.

	      majflt %lu  (12) The number of major faults the process has made
			  which have required loading a memory page from disk.

	      cmajflt %lu (13) The number of major faults that	the  process's
			  waited-for children have made.

	      utime %lu	  (14)	Amount	of  time  that	this  process has been
			  scheduled in user  mode,  measured  in  clock	 ticks
			  (divide  by  sysconf(_SC_CLK_TCK)).	This  includes
			  guest time, guest_time (time spent running a virtual
			  CPU,	see  below), so that applications that are not
			  aware of the guest time field do not lose that  time
			  from their calculations.

	      stime %lu	  (15)	Amount	of  time  that	this  process has been
			  scheduled in kernel mode, measured  in  clock	 ticks
			  (divide by sysconf(_SC_CLK_TCK)).

	      cutime %ld  (16)	Amount	of time that this process's waited-for
			  children have been scheduled in user mode,  measured
			  in  clock  ticks  (divide  by sysconf(_SC_CLK_TCK)).
			  (See also  times(2).)	  This	includes  guest	 time,
			  cguest_time  (time  spent running a virtual CPU, see
			  below).

	      cstime %ld  (17) Amount of time that this	 process's  waited-for
			  children  have  been	scheduled in kernel mode, mea‐
			  sured	    in	   clock     ticks     (divide	    by
			  sysconf(_SC_CLK_TCK)).

	      priority %ld
			  (18)	(Explanation for Linux 2.6) For processes run‐
			  ning a real-time scheduling  policy  (policy	below;
			  see  sched_setscheduler(2)),	this  is  the  negated
			  scheduling priority, minus one; that is, a number in
			  the  range  -2  to  -100, corresponding to real-time
			  priorities 1 to 99.  For processes running  under  a
			  non-real-time	 scheduling  policy,  this  is the raw
			  nice value (setpriority(2)) as  represented  in  the
			  kernel.  The kernel stores nice values as numbers in
			  the range 0 (high) to 39 (low), corresponding to the
			  user-visible nice range of -20 to 19.

			  Before  Linux	 2.6, this was a scaled value based on
			  the scheduler weighting given to this process.

	      nice %ld	  (19) The nice value (see setpriority(2)), a value in
			  the range 19 (low priority) to -20 (high priority).

	      num_threads %ld
			  (20)	Number of threads in this process (since Linux
			  2.6).	 Before kernel 2.6, this field was hard	 coded
			  to 0 as a placeholder for an earlier removed field.

	      itrealvalue %ld
			  (21)	The time in jiffies before the next SIGALRM is
			  sent to the process due to an interval timer.	 Since
			  kernel  2.6.17,  this field is no longer maintained,
			  and is hard coded as 0.

	      starttime %llu (was %lu before Linux 2.6)
			  (22) The time the process started after system boot.
			  In   kernels	 before	 Linux	2.6,  this  value  was
			  expressed in jiffies.	 Since Linux 2.6, the value is
			  expressed	in     clock	ticks	 (divide    by
			  sysconf(_SC_CLK_TCK)).

	      vsize %lu	  (23) Virtual memory size in bytes.

	      rss %ld	  (24) Resident Set Size: number of pages the  process
			  has  in  real	 memory.  This is just the pages which
			  count toward text, data, or stack space.  This  does
			  not  include pages which have not been demand-loaded
			  in, or which are swapped out.

	      rsslim %lu  (25) Current soft limit in bytes on the rss  of  the
			  process;  see the description of RLIMIT_RSS in getr‐
			  limit(2).

	      startcode %lu
			  (26) The address above which program text can run.

	      endcode %lu (27) The address below which program text can run.

	      startstack %lu
			  (28) The address of the start (i.e., bottom) of  the
			  stack.

	      kstkesp %lu (29)	The  current  value of ESP (stack pointer), as
			  found in the kernel stack page for the process.

	      kstkeip %lu (30) The current EIP (instruction pointer).

	      signal %lu  (31) The bitmap of pending signals, displayed	 as  a
			  decimal  number.  Obsolete, because it does not pro‐
			  vide	 information   on   real-time	signals;   use
			  /proc/[pid]/status instead.

	      blocked %lu (32)	The  bitmap of blocked signals, displayed as a
			  decimal number.  Obsolete, because it does not  pro‐
			  vide	 information   on   real-time	signals;   use
			  /proc/[pid]/status instead.

	      sigignore %lu
			  (33) The bitmap of ignored signals, displayed	 as  a
			  decimal  number.  Obsolete, because it does not pro‐
			  vide	 information   on   real-time	signals;   use
			  /proc/[pid]/status instead.

	      sigcatch %lu
			  (34)	The  bitmap  of caught signals, displayed as a
			  decimal number.  Obsolete, because it does not  pro‐
			  vide	 information   on   real-time	signals;   use
			  /proc/[pid]/status instead.

	      wchan %lu	  (35) This is the "channel" in which the  process  is
			  waiting.   It	 is  the  address of a location in the
			  kernel where the process is  sleeping.   The	corre‐
			  sponding    symbolic	  name	 can   be   found   in
			  /proc/[pid]/wchan.

	      nswap %lu	  (36) Number of pages swapped (not maintained).

	      cnswap %lu  (37) Cumulative nswap for child processes (not main‐
			  tained).

	      exit_signal %d (since Linux 2.1.22)
			  (38) Signal to be sent to parent when we die.

	      processor %d (since Linux 2.2.8)
			  (39) CPU number last executed on.

	      rt_priority %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
			  (40)	Real-time scheduling priority, a number in the
			  range 1 to 99 for processes scheduled under a	 real-
			  time	policy, or 0, for non-real-time processes (see
			  sched_setscheduler(2)).

	      policy %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
			  (41) Scheduling policy (see  sched_setscheduler(2)).
			  Decode using the SCHED_* constants in linux/sched.h.

	      delayacct_blkio_ticks %llu (since Linux 2.6.18)
			  (42)	Aggregated block I/O delays, measured in clock
			  ticks (centiseconds).

	      guest_time %lu (since Linux 2.6.24)
			  (43) Guest time of the process (time spent running a
			  virtual  CPU for a guest operating system), measured
			  in clock ticks (divide by sysconf(_SC_CLK_TCK)).

	      cguest_time %ld (since Linux 2.6.24)
			  (44) Guest time of the process's children,  measured
			  in clock ticks (divide by sysconf(_SC_CLK_TCK)).

       /proc/[pid]/statm
	      Provides information about memory usage, measured in pages.  The
	      columns are:

		  size	     (1) total program size
			     (same as VmSize in /proc/[pid]/status)
		  resident   (2) resident set size
			     (same as VmRSS in /proc/[pid]/status)
		  share	     (3) shared pages (i.e., backed by a file)
		  text	     (4) text (code)
		  lib	     (5) library (unused in Linux 2.6)
		  data	     (6) data + stack
		  dt	     (7) dirty pages (unused in Linux 2.6)

       /proc/[pid]/status
	      Provides	much  of  the  information  in	/proc/[pid]/stat   and
	      /proc/[pid]/statm in a format that's easier for humans to parse.
	      Here's an example:

		  $ cat /proc/$$/status
		  Name:	  bash
		  State:  S (sleeping)
		  Tgid:	  3515
		  Pid:	  3515
		  PPid:	  3452
		  TracerPid:	  0
		  Uid:	  1000	  1000	  1000	  1000
		  Gid:	  100	  100	  100	  100
		  FDSize: 256
		  Groups: 16 33 100
		  VmPeak:     9136 kB
		  VmSize:     7896 kB
		  VmLck:	 0 kB
		  VmHWM:      7572 kB
		  VmRSS:      6316 kB
		  VmData:     5224 kB
		  VmStk:	88 kB
		  VmExe:       572 kB
		  VmLib:      1708 kB
		  VmPTE:	20 kB
		  Threads:	  1
		  SigQ:	  0/3067
		  SigPnd: 0000000000000000
		  ShdPnd: 0000000000000000
		  SigBlk: 0000000000010000
		  SigIgn: 0000000000384004
		  SigCgt: 000000004b813efb
		  CapInh: 0000000000000000
		  CapPrm: 0000000000000000
		  CapEff: 0000000000000000
		  CapBnd: ffffffffffffffff
		  Cpus_allowed:	  00000001
		  Cpus_allowed_list:	  0
		  Mems_allowed:	  1
		  Mems_allowed_list:	  0
		  voluntary_ctxt_switches:	  150
		  nonvoluntary_ctxt_switches:	  545

	      The fields are as follows:

	      * Name: Command run by this process.

	      * State: Current state of the process.  One of "R (running)", "S
		(sleeping)",  "D  (disk	 sleep)",  "T  (stopped)", "T (tracing
		stop)", "Z (zombie)", or "X (dead)".

	      * Tgid: Thread group ID (i.e., Process ID).

	      * Pid: Thread ID (see gettid(2)).

	      * PPid: PID of parent process.

	      * TracerPid: PID of process tracing this process (0 if not being
		traced).

	      * Uid,  Gid:  Real,  effective,  saved  set, and filesystem UIDs
		(GIDs).

	      * FDSize: Number of file descriptor slots currently allocated.

	      * Groups: Supplementary group list.

	      * VmPeak: Peak virtual memory size.

	      * VmSize: Virtual memory size.

	      * VmLck: Locked memory size (see mlock(3)).

	      * VmHWM: Peak resident set size ("high water mark").

	      * VmRSS: Resident set size.

	      * VmData, VmStk, VmExe: Size of data, stack, and text segments.

	      * VmLib: Shared library code size.

	      * VmPTE: Page table entries size (since Linux 2.6.10).

	      * Threads: Number of threads in process containing this thread.

	      * SigQ: This field contains  two	slash-separated	 numbers  that
		relate to queued signals for the real user ID of this process.
		The first of these is the number of currently  queued  signals
		for this real user ID, and the second is the resource limit on
		the number  of	queued	signals	 for  this  process  (see  the
		description of RLIMIT_SIGPENDING in getrlimit(2)).

	      * SigPnd,	 ShdPnd:  Number of signals pending for thread and for
		process as a whole (see pthreads(7) and signal(7)).

	      * SigBlk,	 SigIgn,  SigCgt:  Masks  indicating   signals	 being
		blocked, ignored, and caught (see signal(7)).

	      * CapInh,	 CapPrm,  CapEff:  Masks  of  capabilities  enabled in
		inheritable, permitted,	 and  effective	 sets  (see  capabili‐
		ties(7)).

	      * CapBnd:	 Capability  Bounding  set  (since  kernel 2.6.26, see
		capabilities(7)).

	      * Cpus_allowed: Mask of CPUs  on	which  this  process  may  run
		(since Linux 2.6.24, see cpuset(7)).

	      * Cpus_allowed_list:  Same  as  previous,	 but  in "list format"
		(since Linux 2.6.26, see cpuset(7)).

	      * Mems_allowed: Mask of memory nodes  allowed  to	 this  process
		(since Linux 2.6.24, see cpuset(7)).

	      * Mems_allowed_list:  Same  as  previous,	 but  in "list format"
		(since Linux 2.6.26, see cpuset(7)).

	      * voluntary_context_switches,	nonvoluntary_context_switches:
		Number	of  voluntary  and involuntary context switches (since
		Linux 2.6.23).

       /proc/[pid]/task (since Linux 2.6.0-test6)
	      This is a directory that	contains  one  subdirectory  for  each
	      thread  in  the  process.	  The name of each subdirectory is the
	      numerical thread ID  ([tid])  of	the  thread  (see  gettid(2)).
	      Within  each  of	these  subdirectories, there is a set of files
	      with the same names and contents as under the /proc/[pid] direc‐
	      tories.  For attributes that are shared by all threads, the con‐
	      tents for each of the files under the task/[tid]	subdirectories
	      will  be	the  same  as  in the corresponding file in the parent
	      /proc/[pid] directory (e.g., in a multithreaded process, all  of
	      the  task/[tid]/cwd  files  will	have  the  same	 value	as the
	      /proc/[pid]/cwd file in the parent directory, since all  of  the
	      threads in a process share a working directory).	For attributes
	      that are distinct for each thread, the corresponding files under
	      task/[tid]  may  have  different values (e.g., various fields in
	      each of the task/[tid]/status files may be  different  for  each
	      thread).

	      In a multithreaded process, the contents of the /proc/[pid]/task
	      directory are not available if the main thread has already  ter‐
	      minated (typically by calling pthread_exit(3)).

       /proc/[pid]/wchan (since Linux 2.6.0)
	      The  symbolic  name  corresponding to the location in the kernel
	      where the process is sleeping.

       /proc/apm
	      Advanced power management version and battery  information  when
	      CONFIG_APM is defined at kernel compilation time.

       /proc/bus
	      Contains subdirectories for installed busses.

       /proc/bus/pccard
	      Subdirectory  for	 PCMCIA	 devices  when CONFIG_PCMCIA is set at
	      kernel compilation time.

       /proc/[pid]/timers (since Linux 3.10)
	      A list of the POSIX timers for  this  process.   Each  timer  is
	      listed  with  a  line  that  started with the string "ID:".  For
	      example:

		  ID: 1
		  signal: 60/00007fff86e452a8
		  notify: signal/pid.2634
		  ClockID: 0
		  ID: 0
		  signal: 60/00007fff86e452a8
		  notify: signal/pid.2634
		  ClockID: 1

	      The lines shown for each timer have the following meanings:

	      ID     The ID for this timer.  This is not the same as the timer
		     ID	 returned  by  timer_create(2); rather, it is the same
		     kernel-internal ID that is available via  the  si_timerid
		     field of the siginfo_t structure (see sigaction(2)).

	      signal This is the signal number that this timer uses to deliver
		     notifications  followed  by  a  slash,   and   then   the
		     sigev_value.sival_ptr  value  supplied to the signal han‐
		     dler.  Valid only for timers that notify via a signal.

	      notify The part before the slash specifies  the  mechanism  that
		     this  timer  uses to deliver notifications, and is one of
		     "thread", "signal", or "none".  Immediately following the
		     slash   is	 either	 the  string  "tid"  for  timers  with
		     SIGEV_THREAD_ID notification, or "pid"  for  timers  that
		     notify by other mechanisms.  Following the "." is the PID
		     of the process that will be delivered  a  signal  if  the
		     timer delivers notifications via a signal.

	      ClockID
		     This  field  identifies the clock that the timer uses for
		     measuring time.  For most clocks, this is a  number  that
		     matches  one  of the user-space CLOCK_* constants exposed
		     via <time.h>.   CLOCK_PROCESS_CPUTIME_ID  timers  display
		     with     a	    value     of    -6	  in	this	field.
		     CLOCK_THREAD_CPUTIME_ID timers display with a value of -2
		     in this field.

       /proc/bus/pccard/drivers

       /proc/bus/pci
	      Contains	various bus subdirectories and pseudo-files containing
	      information about PCI  busses,  installed	 devices,  and	device
	      drivers.	Some of these files are not ASCII.

       /proc/bus/pci/devices
	      Information  about  PCI  devices.	  They may be accessed through
	      lspci(8) and setpci(8).

       /proc/cmdline
	      Arguments passed to the Linux kernel at boot time.   Often  done
	      via a boot manager such as lilo(8) or grub(8).

       /proc/config.gz (since Linux 2.6)
	      This  file  exposes  the configuration options that were used to
	      build the currently running kernel, in the same format  as  they
	      would  be shown in the .config file that resulted when configur‐
	      ing the kernel (using make xconfig, make	config,	 or  similar).
	      The  file	 contents  are	compressed;  view or search them using
	      zcat(1) and zgrep(1).  As long as no changes have been  made  to
	      the following file, the contents of /proc/config.gz are the same
	      as those provided by :

		  cat /lib/modules/$(uname -r)/build/.config

	      /proc/config.gz is provided only if  the	kernel	is  configured
	      with CONFIG_IKCONFIG_PROC.

       /proc/cpuinfo
	      This  is	a  collection of CPU and system architecture dependent
	      items, for each supported architecture a	different  list.   Two
	      common   entries	are  processor	which  gives  CPU  number  and
	      bogomips; a system constant that	is  calculated	during	kernel
	      initialization.	SMP  machines  have  information for each CPU.
	      The lscpu(1) command gathers its information from this file.

       /proc/devices
	      Text listing of major numbers and device groups.	 This  can  be
	      used by MAKEDEV scripts for consistency with the kernel.

       /proc/diskstats (since Linux 2.5.69)
	      This  file  contains  disk  I/O statistics for each disk device.
	      See the Linux kernel source file	Documentation/iostats.txt  for
	      further information.

       /proc/dma
	      This  is a list of the registered ISA DMA (direct memory access)
	      channels in use.

       /proc/driver
	      Empty subdirectory.

       /proc/execdomains
	      List of the execution domains (ABI personalities).

       /proc/fb
	      Frame buffer information when CONFIG_FB is defined during kernel
	      compilation.

       /proc/filesystems
	      A	 text  listing	of  the filesystems which are supported by the
	      kernel, namely filesystems which were compiled into  the	kernel
	      or  whose	 kernel	 modules  are  currently  loaded.   (See  also
	      filesystems(5).)	If a filesystem is marked with	"nodev",  this
	      means  that  it  does  not  require a block device to be mounted
	      (e.g., virtual filesystem, network filesystem).

	      Incidentally, this file may be used by mount(8) when no filesys‐
	      tem  is specified and it didn't manage to determine the filesys‐
	      tem type.	 Then filesystems contained in	this  file  are	 tried
	      (excepted those that are marked with "nodev").

       /proc/fs
	      Empty subdirectory.

       /proc/ide
	      This  directory  exists  on systems with the IDE bus.  There are
	      directories for each IDE channel	and  attached  device.	 Files
	      include:

		  cache		     buffer size in KB
		  capacity	     number of sectors
		  driver	     driver version
		  geometry	     physical and logical geometry
		  identify	     in hexadecimal
		  media		     media type
		  model		     manufacturer's model number
		  settings	     drive settings
		  smart_thresholds   in hexadecimal
		  smart_values	     in hexadecimal

	      The  hdparm(8)  utility provides access to this information in a
	      friendly format.

       /proc/interrupts
	      This is used to record the number of interrupts per CPU  per  IO
	      device.	Since  Linux 2.6.24, for the i386 and x86_64 architec‐
	      tures, at least, this also includes interrupts internal  to  the
	      system  (that is, not associated with a device as such), such as
	      NMI (nonmaskable interrupt), LOC (local  timer  interrupt),  and
	      for  SMP	systems,  TLB (TLB flush interrupt), RES (rescheduling
	      interrupt), CAL (remote function call interrupt),	 and  possibly
	      others.  Very easy to read formatting, done in ASCII.

       /proc/iomem
	      I/O memory map in Linux 2.4.

       /proc/ioports
	      This is a list of currently registered Input-Output port regions
	      that are in use.

       /proc/kallsyms (since Linux 2.5.71)
	      This holds the kernel exported symbol definitions	 used  by  the
	      modules(X)  tools to dynamically link and bind loadable modules.
	      In Linux 2.5.47 and earlier, a similar file with	slightly  dif‐
	      ferent syntax was named ksyms.

       /proc/kcore
	      This  file  represents  the physical memory of the system and is
	      stored in the ELF core file format.  With this pseudo-file,  and
	      an unstripped kernel (/usr/src/linux/vmlinux) binary, GDB can be
	      used to examine the current state of any kernel data structures.

	      The total length of the file is  the  size  of  physical	memory
	      (RAM) plus 4KB.

       /proc/kmsg
	      This  file  can  be used instead of the syslog(2) system call to
	      read kernel messages.  A process must have superuser  privileges
	      to  read	this file, and only one process should read this file.
	      This file should not be read if  a  syslog  process  is  running
	      which uses the syslog(2) system call facility to log kernel mes‐
	      sages.

	      Information in this file is retrieved with the dmesg(1) program.

       /proc/ksyms (Linux 1.1.23-2.5.47)
	      See /proc/kallsyms.

       /proc/loadavg
	      The first three fields in this file  are	load  average  figures
	      giving  the number of jobs in the run queue (state R) or waiting
	      for disk I/O (state D) averaged over 1, 5, and 15 minutes.  They
	      are  the same as the load average numbers given by uptime(1) and
	      other programs.  The fourth field consists of two numbers	 sepa‐
	      rated  by a slash (/).  The first of these is the number of cur‐
	      rently runnable kernel scheduling entities (processes, threads).
	      The  value  after	 the  slash is the number of kernel scheduling
	      entities that currently exist on the system.  The fifth field is
	      the  PID	of  the	 process that was most recently created on the
	      system.

       /proc/locks
	      This file shows current file locks (flock(2) and	fcntl(2))  and
	      leases (fcntl(2)).

       /proc/malloc (only up to and including Linux 2.2)
	      This  file  is  present  only if CONFIG_DEBUG_MALLOC was defined
	      during compilation.

       /proc/meminfo
	      This file reports statistics about memory usage on  the  system.
	      It is used by free(1) to report the amount of free and used mem‐
	      ory (both physical and swap) on the system as well as the shared
	      memory  and  buffers  used by the kernel.	 Each line of the file
	      consists of a parameter name, followed by a colon, the value  of
	      the  parameter,  and an option unit of measurement (e.g., "kB").
	      The list below describes the  parameter  names  and  the	format
	      specifier	 required  to  read  the field value.  Except as noted
	      below, all of the fields have been present since at least	 Linux
	      2.6.0.  Some fileds are displayed only if the kernel was config‐
	      ured with various options; those dependencies are noted  in  the
	      list.

	      MemTotal %lu
		     Total usable RAM (i.e., physical RAM minus a few reserved
		     bits and the kernel binary code).

	      MemFree %lu
		     The sum of LowFree+HighFree.

	      Buffers %lu
		     Relatively temporary storage for  raw  disk  blocks  that
		     shouldn't get tremendously large (20MB or so).

	      Cached %lu
		     In-memory	cache  for  files read from the disk (the page
		     cache).  Doesn't include SwapCached.

	      SwapCached %lu
		     Memory that once was swapped out, is swapped back in  but
		     still  also  is in the swap file.	(If memory pressure is
		     high, these pages don't need  to  be  swapped  out	 again
		     because  they  are	 already in the swap file.  This saves
		     I/O.)

	      Active %lu
		     Memory that has been used more recently and  usually  not
		     reclaimed unless absolutely necessary.

	      Inactive %lu
		     Memory  which  has	 been  less recently used.  It is more
		     eligible to be reclaimed for other purposes.

	      Active(anon) %lu (since Linux 2.6.28)
		     [To be documented.]

	      Inactive(anon) %lu (since Linux 2.6.28)
		     [To be documented.]

	      Active(file) %lu (since Linux 2.6.28)
		     [To be documented.]

	      Inactive(file) %lu (since Linux 2.6.28)
		     [To be documented.]

	      Unevictable %lu (since Linux 2.6.28)
		     (From Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU  was
		     required.)	 [To be documented.]

	      Mlocked %lu (since Linux 2.6.28)
		     (From  Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU was
		     required.)	 [To be documented.]

	      HighTotal %lu
		     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
		     Total  amount  of	highmem.   Highmem is all memory above
		     ~860MB of physical memory.	 Highmem areas are for use  by
		     user-space	 programs,  or for the page cache.  The kernel
		     must use tricks to access this memory, making  it	slower
		     to access than lowmem.

	      HighFree %lu
		     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
		     Amount of free highmem.

	      LowTotal %lu
		     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
		     Total  amount  of	lowmem.	 Lowmem is memory which can be
		     used for everything that highmem can be used for, but  it
		     is	 also  available for the kernel's use for its own data
		     structures.  Among many other things, it is where	every‐
		     thing  from  Slab	is  allocated.	Bad things happen when
		     you're out of lowmem.

	      LowFree %lu
		     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
		     Amount of free lowmem.

	      MmapCopy %lu (since Linux 2.6.29)
		     (CONFIG_MMU is required.)	[To be documented.]

	      SwapTotal %lu
		     Total amount of swap space available.

	      SwapFree %lu
		     Amount of swap space that is currently unused.

	      Dirty %lu
		     Memory which is waiting to get written back to the disk.

	      Writeback %lu
		     Memory which is actively being written back to the disk.

	      AnonPages %lu (since Linux 2.6.18)
		     Non-file backed pages mapped into user-space page tables.

	      Mapped %lu
		     Files which have been mmaped, such as libraries.

	      Shmem %lu (since Linux 2.6.32)
		     [To be documented.]

	      Slab %lu
		     In-kernel data structures cache.

	      SReclaimable %lu (since Linux 2.6.19)
		     Part of Slab, that might be reclaimed, such as caches.

	      SUnreclaim %lu (since Linux 2.6.19)
		     Part  of  Slab,  that cannot be reclaimed on memory pres‐
		     sure.

	      KernelStack %lu (since Linux 2.6.32)
		     Amount of memory allocated to kernel stacks.

	      PageTables %lu (since Linux 2.6.18)
		     Amount of memory dedicated to the lowest  level  of  page
		     tables.

	      Quicklists %lu (since Linux 2.6.27)
		     (CONFIG_QUICKLIST is required.)  [To be documented.]

	      NFS_Unstable %lu (since Linux 2.6.18)
		     NFS  pages	 sent  to the server, but not yet committed to
		     stable storage.

	      Bounce %lu (since Linux 2.6.18)
		     Memory used for block device "bounce buffers".

	      WritebackTmp %lu (since Linux 2.6.26)
		     Memory used by FUSE for temporary writeback buffers.

	      CommitLimit %lu (since Linux 2.6.10)
		     Based on the  overcommit  ratio  ('vm.overcommit_ratio'),
		     this  is  the total amount of  memory currently available
		     to be allocated on the system.  This limit is adhered  to
		     only  if  strict overcommit accounting is enabled (mode 2
		     in /proc/sys/vm/overcommit_ratio).	  The  CommitLimit  is
		     calculated using the following formula:

			 CommitLimit =
			     ([total RAM pages] - [total huge TLB pages]) *
			     overcommit_ratio / 100 + [total swap pages]

		     For example, on a system with 1GB of physical RAM and 7GB
		     of swap with  a  overcommit_ratio	of  30,	 this  formula
		     yields a CommitLimit of 7.3GB.  For more details, see the
		     memory overcommit documentation in the kernel source file
		     Documentation/vm/overcommit-accounting.

	      Committed_AS %lu
		     The  amount  of memory presently allocated on the system.
		     The committed memory is a sum of all of the memory	 which
		     has  been allocated by processes, even if it has not been
		     "used" by them as of yet.	A process which allocates  1GB
		     of	 memory (using malloc(3) or similar), but touches only
		     300MB of that memory will show up as using only 300MB  of
		     memory even if it has the address space allocated for the
		     entire 1GB.  This 1GB is memory which has	been  "commit‐
		     ted"  to  by  the	VM  and can be used at any time by the
		     allocating application.  With strict  overcommit  enabled
		     on	 the  system  (mode 2 /proc/sys/vm/overcommit_memory),
		     allocations which would exceed the CommitLimit  (detailed
		     above)  will  not	be  permitted.	 This is useful if one
		     needs to guarantee that processes will not	 fail  due  to
		     lack  of  memory  once  that memory has been successfully
		     allocated.

	      VmallocTotal %lu
		     Total size of vmalloc memory area.

	      VmallocUsed %lu
		     Amount of vmalloc area which is used.

	      VmallocChunk %lu
		     Largest contiguous block of vmalloc area which is free.

	      HardwareCorrupted %lu (since Linux 2.6.32)
		     (CONFIG_MEMORY_FAILURE is required.)  [To be documented.]

	      AnonHugePages %lu (since Linux 2.6.38)
		     (CONFIG_TRANSPARENT_HUGEPAGE  is	required.)    Non-file
		     backed huge pages mapped into user-space page tables.

	      HugePages_Total %lu
		     (CONFIG_HUGETLB_PAGE  is required.)  The size of the pool
		     of huge pages.

	      HugePages_Free %lu
		     (CONFIG_HUGETLB_PAGE is required.)	 The  number  of  huge
		     pages in the pool that are not yet allocated.

	      HugePages_Rsvd %lu (since Linux 2.6.17)
		     (CONFIG_HUGETLB_PAGE is required.)	 This is the number of
		     huge pages for which a commitment to  allocate  from  the
		     pool  has been made, but no allocation has yet been made.
		     These reserved huge pages guarantee that  an  application
		     will  be  able  to	 allocate a huge page from the pool of
		     huge pages at fault time.

	      HugePages_Surp %lu (since Linux 2.6.24)
		     (CONFIG_HUGETLB_PAGE is required.)	 This is the number of
		     huge   pages   in	 the   pool   above   the   value   in
		     /proc/sys/vm/nr_hugepages.	 The maximum number of surplus
		     huge  pages  is  controlled  by  /proc/sys/vm/nr_overcom‐
		     mit_hugepages.

	      Hugepagesize %lu
		     (CONFIG_HUGETLB_PAGE is  required.)   The	size  of  huge
		     pages.

       /proc/modules
	      A	 text list of the modules that have been loaded by the system.
	      See also lsmod(8).

       /proc/mounts
	      Before kernel 2.4.19, this file was a list of all	 the  filesys‐
	      tems  currently mounted on the system.  With the introduction of
	      per-process mount namespaces in Linux 2.4.19, this file became a
	      link  to	/proc/self/mounts, which lists the mount points of the
	      process's own mount namespace.  The format of this file is docu‐
	      mented in fstab(5).

       /proc/mtrr
	      Memory  Type  Range Registers.  See the Linux kernel source file
	      Documentation/mtrr.txt for details.

       /proc/net
	      various net pseudo-files, all of which give the status  of  some
	      part  of the networking layer.  These files contain ASCII struc‐
	      tures and are, therefore, readable with  cat(1).	 However,  the
	      standard	netstat(8) suite provides much cleaner access to these
	      files.

       /proc/net/arp
	      This holds an ASCII readable dump of the kernel ARP  table  used
	      for  address resolutions.	 It will show both dynamically learned
	      and preprogrammed ARP entries.  The format is:

	IP address     HW type	 Flags	   HW address	       Mask   Device
	192.168.0.50   0x1	 0x2	   00:50:BF:25:68:F3   *      eth0
	192.168.0.250  0x1	 0xc	   00:00:00:00:00:00   *      eth0

	      Here "IP address" is the IPv4 address of the machine and the "HW
	      type"  is	 the  hardware	type of the address from RFC 826.  The
	      flags are the internal flags of the ARP structure (as defined in
	      /usr/include/linux/if_arp.h)  and	 the  "HW address" is the data
	      link layer mapping for that IP address if it is known.

       /proc/net/dev
	      The dev pseudo-file contains network device status  information.
	      This  gives  the number of received and sent packets, the number
	      of errors and collisions and other basic statistics.  These  are
	      used  by	the  ifconfig(8) program to report device status.  The
	      format is:

 Inter-|   Receive						  |  Transmit
  face |bytes	 packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
     lo: 2776770   11307    0	 0    0	    0	       0	 0  2776770   11307    0    0	 0     0       0	  0
   eth0: 1215645    2751    0	 0    0	    0	       0	 0  1782404    4324    0    0	 0   427       0	  0
   ppp0: 1622270    5552    1	 0    0	    0	       0	 0   354130    5669    0    0	 0     0       0	  0
   tap0:    7714      81    0	 0    0	    0	       0	 0     7714	 81    0    0	 0     0       0	  0

       /proc/net/dev_mcast
	      Defined in /usr/src/linux/net/core/dev_mcast.c:
		   indx interface_name	dmi_u dmi_g dmi_address
		   2	eth0		1     0	    01005e000001
		   3	eth1		1     0	    01005e000001
		   4	eth2		1     0	    01005e000001

       /proc/net/igmp
	      Internet	  Group	   Management	 Protocol.	Defined	    in
	      /usr/src/linux/net/core/igmp.c.

       /proc/net/rarp
	      This  file uses the same format as the arp file and contains the
	      current reverse mapping database used to provide rarp(8) reverse
	      address  lookup  services.   If  RARP is not configured into the
	      kernel, this file will not be present.

       /proc/net/raw
	      Holds a dump of the RAW socket table.  Much of  the  information
	      is  not of use apart from debugging.  The "sl" value is the ker‐
	      nel hash slot for the socket, the "local_address" is  the	 local
	      address  and  protocol number pair.  "St" is the internal status
	      of the socket.  The "tx_queue" and "rx_queue" are	 the  outgoing
	      and  incoming  data  queue in terms of kernel memory usage.  The
	      "tr", "tm->when", and "rexmits" fields are not used by RAW.  The
	      "uid"  field  holds  the	effective  UID	of  the creator of the
	      socket.

       /proc/net/snmp
	      This file holds the ASCII data needed for the IP, ICMP, TCP, and
	      UDP management information bases for an SNMP agent.

       /proc/net/tcp
	      Holds  a	dump of the TCP socket table.  Much of the information
	      is not of use apart from debugging.  The "sl" value is the  ker‐
	      nel  hash	 slot for the socket, the "local_address" is the local
	      address and port number pair.  The "rem_address" is  the	remote
	      address and port number pair (if connected).  "St" is the inter‐
	      nal status of the socket.	 The "tx_queue" and "rx_queue" are the
	      outgoing	and  incoming  data  queue  in	terms of kernel memory
	      usage.  The "tr", "tm->when", and "rexmits" fields hold internal
	      information  of  the kernel socket state and are only useful for
	      debugging.  The "uid" field holds the effective UID of the  cre‐
	      ator of the socket.

       /proc/net/udp
	      Holds  a	dump of the UDP socket table.  Much of the information
	      is not of use apart from debugging.  The "sl" value is the  ker‐
	      nel  hash	 slot for the socket, the "local_address" is the local
	      address and port number pair.  The "rem_address" is  the	remote
	      address  and port number pair (if connected). "St" is the inter‐
	      nal status of the socket.	 The "tx_queue" and "rx_queue" are the
	      outgoing	and  incoming  data  queue  in	terms of kernel memory
	      usage.  The "tr", "tm->when", and "rexmits" fields are not  used
	      by  UDP.	The "uid" field holds the effective UID of the creator
	      of the socket.  The format is:

 sl  local_address rem_address	 st tx_queue rx_queue tr rexmits  tm->when uid
  1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0
  1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0
  1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0

       /proc/net/unix
	      Lists the UNIX domain sockets  present  within  the  system  and
	      their status.  The format is:
	      Num RefCount Protocol Flags    Type St Path
	       0: 00000002 00000000 00000000 0001 03
	       1: 00000001 00000000 00010000 0001 01 /dev/printer

	      Here  "Num"  is  the kernel table slot number, "RefCount" is the
	      number of users of the socket, "Protocol" is currently always 0,
	      "Flags"  represent  the internal kernel flags holding the status
	      of the socket.  Currently, type is always "1" (UNIX domain data‐
	      gram  sockets are not yet supported in the kernel).  "St" is the
	      internal state of the socket and Path is the bound path (if any)
	      of the socket.

       /proc/partitions
	      Contains	the  major and minor numbers of each partition as well
	      as the number of 1024-byte blocks and the partition name.

       /proc/pci
	      This is a listing of all PCI devices found  during  kernel  ini‐
	      tialization and their configuration.

	      This  file has been deprecated in favor of a new /proc interface
	      for PCI  (/proc/bus/pci).	  It  became  optional	in  Linux  2.2
	      (available  with CONFIG_PCI_OLD_PROC set at kernel compilation).
	      It became once more nonoptionally enabled in Linux  2.4.	 Next,
	      it  was  deprecated  in  Linux  2.6  (still  available with CON‐
	      FIG_PCI_LEGACY_PROC set), and finally removed  altogether	 since
	      Linux 2.6.17.

       /proc/profile (since Linux 2.4)
	      This file is present only if the kernel was booted with the pro‐
	      file=1 command-line option.  It exposes kernel profiling	infor‐
	      mation  in  a  binary format for use by readprofile(1).  Writing
	      (e.g., an empty string) to this file resets the profiling	 coun‐
	      ters; on some architectures, writing a binary integer "profiling
	      multiplier" of size sizeof(int)  sets  the  profiling  interrupt
	      frequency.

       /proc/scsi
	      A directory with the scsi mid-level pseudo-file and various SCSI
	      low-level driver directories, which contain a file for each SCSI
	      host  in	this system, all of which give the status of some part
	      of the SCSI IO subsystem.	 These files contain ASCII  structures
	      and are, therefore, readable with cat(1).

	      You  can also write to some of the files to reconfigure the sub‐
	      system or switch certain features on or off.

       /proc/scsi/scsi
	      This is a listing of all SCSI devices known to the kernel.   The
	      listing  is  similar  to	the one seen during bootup.  scsi cur‐
	      rently supports only the add-single-device command which	allows
	      root to add a hotplugged device to the list of known devices.

	      The command

		  echo 'scsi add-single-device 1 0 5 0' > /proc/scsi/scsi

	      will  cause host scsi1 to scan on SCSI channel 0 for a device on
	      ID 5 LUN 0.  If there is already a device known on this  address
	      or the address is invalid, an error will be returned.

       /proc/scsi/[drivername]
	      [drivername]  can	 currently  be	NCR53c7xx,  aha152x,  aha1542,
	      aha1740, aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000,
	      pas16,  qlogic,  scsi_debug, seagate, t128, u15-24f, ultrastore,
	      or wd7000.  These directories show up for all drivers that  reg‐
	      istered  at  least  one  SCSI HBA.  Every directory contains one
	      file per registered host.	 Every host-file is  named  after  the
	      number the host was assigned during initialization.

	      Reading these files will usually show driver and host configura‐
	      tion, statistics, and so on.

	      Writing to these files  allows  different	 things	 on  different
	      hosts.   For  example,  with the latency and nolatency commands,
	      root can switch on and off command latency measurement  code  in
	      the  eata_dma driver.  With the lockup and unlock commands, root
	      can control bus lockups simulated by the scsi_debug driver.

       /proc/self
	      This  directory  refers  to  the	process	 accessing  the	 /proc
	      filesystem, and is identical to the /proc directory named by the
	      process ID of the same process.

       /proc/slabinfo
	      Information about kernel caches.	Since Linux 2.6.16  this  file
	      is  present  only if the CONFIG_SLAB kernel configuration option
	      is enabled.  The columns in /proc/slabinfo are:

		  cache-name
		  num-active-objs
		  total-objs
		  object-size
		  num-active-slabs
		  total-slabs
		  num-pages-per-slab

	      See slabinfo(5) for details.

       /proc/stat
	      kernel/system statistics.	  Varies  with	architecture.	Common
	      entries include:

	      cpu  3357 0 4313 1362393
		     The   amount  of  time,  measured	in  units  of  USER_HZ
		     (1/100ths	of  a  second  on  most	  architectures,   use
		     sysconf(_SC_CLK_TCK) to obtain the right value), that the
		     system spent in various states:

		     user   (1) Time spent in user mode.

		     nice   (2) Time spent in  user  mode  with	 low  priority
			    (nice).

		     system (3) Time spent in system mode.

		     idle   (4)	 Time  spent  in  the  idle  task.  This value
			    should be USER_HZ times the second	entry  in  the
			    /proc/uptime pseudo-file.

		     iowait (since Linux 2.5.41)
			    (5) Time waiting for I/O to complete.

		     irq (since Linux 2.6.0-test4)
			    (6) Time servicing interrupts.

		     softirq (since Linux 2.6.0-test4)
			    (7) Time servicing softirqs.

		     steal (since Linux 2.6.11)
			    (8)	 Stolen time, which is the time spent in other
			    operating systems when running  in	a  virtualized
			    environment

		     guest (since Linux 2.6.24)
			    (9)	 Time  spent  running  a virtual CPU for guest
			    operating systems under the control of  the	 Linux
			    kernel.

		     guest_nice (since Linux 2.6.33)
			    (10) Time spent running a niced guest (virtual CPU
			    for guest operating systems under the  control  of
			    the Linux kernel).

	      page 5741 1808
		     The  number  of  pages the system paged in and the number
		     that were paged out (from disk).

	      swap 1 0
		     The number of swap pages that have been  brought  in  and
		     out.

	      intr 1462898
		     This  line shows counts of interrupts serviced since boot
		     time, for each of the possible  system  interrupts.   The
		     first  column  is	the  total of all interrupts serviced;
		     each subsequent column is	the  total  for	 a  particular
		     interrupt.

	      disk_io: (2,0):(31,30,5764,1,2) (3,0):...
		     (major,disk_idx):(noinfo,	   read_io_ops,	    blks_read,
		     write_io_ops, blks_written)
		     (Linux 2.4 only)

	      ctxt 115315
		     The number of context switches that the system underwent.

	      btime 769041601
		     boot  time,  in  seconds  since  the  Epoch,   1970-01-01
		     00:00:00 +0000 (UTC).

	      processes 86031
		     Number of forks since boot.

	      procs_running 6
		     Number  of	 processes  in	runnable state.	 (Linux 2.5.45
		     onward.)

	      procs_blocked 2
		     Number of processes blocked waiting for I/O to  complete.
		     (Linux 2.5.45 onward.)

       /proc/swaps
	      Swap areas in use.  See also swapon(8).

       /proc/sys
	      This directory (present since 1.3.57) contains a number of files
	      and subdirectories corresponding	to  kernel  variables.	 These
	      variables	 can  be  read	and sometimes modified using the /proc
	      filesystem, and the (deprecated) sysctl(2) system call.

       /proc/sys/abi (since Linux 2.4.10)
	      This directory may contain files with application binary	infor‐
	      mation.	 See   the   Linux   kernel   source  file  Documenta‐
	      tion/sysctl/abi.txt for more information.

       /proc/sys/debug
	      This directory may be empty.

       /proc/sys/dev
	      This  directory  contains	 device-specific  information	(e.g.,
	      dev/cdrom/info).	On some systems, it may be empty.

       /proc/sys/fs
	      This  directory contains the files and subdirectories for kernel
	      variables related to filesystems.

       /proc/sys/fs/binfmt_misc
	      Documentation for files in this directory can be	found  in  the
	      Linux kernel sources in Documentation/binfmt_misc.txt.

       /proc/sys/fs/dentry-state (since Linux 2.2)
	      This file contains information about the status of the directory
	      cache (dcache).	The  file  contains  six  numbers,  nr_dentry,
	      nr_unused,   age_limit   (age  in	 seconds),  want_pages	(pages
	      requested by system) and two dummy values.

	      * nr_dentry  is  the  number  of	allocated   dentries   (dcache
		entries).  This field is unused in Linux 2.2.

	      * nr_unused is the number of unused dentries.

	      * age_limit is the age in seconds after which dcache entries can
		be reclaimed when memory is short.

	      * want_pages   is	  nonzero   when   the	 kernel	  has	called
		shrink_dcache_pages() and the dcache isn't pruned yet.

       /proc/sys/fs/dir-notify-enable
	      This file can be used to disable or enable the dnotify interface
	      described in fcntl(2) on a system-wide basis.  A value of	 0  in
	      this file disables the interface, and a value of 1 enables it.

       /proc/sys/fs/dquot-max
	      This file shows the maximum number of cached disk quota entries.
	      On some (2.4) systems, it is not present.	 If the number of free
	      cached  disk quota entries is very low and you have some awesome
	      number of simultaneous system users, you might want to raise the
	      limit.

       /proc/sys/fs/dquot-nr
	      This  file  shows the number of allocated disk quota entries and
	      the number of free disk quota entries.

       /proc/sys/fs/epoll (since Linux 2.6.28)
	      This directory contains the file max_user_watches, which can  be
	      used  to limit the amount of kernel memory consumed by the epoll
	      interface.  For further details, see epoll(7).

       /proc/sys/fs/file-max
	      This file defines a system-wide limit  on	 the  number  of  open
	      files  for  all processes.  (See also setrlimit(2), which can be
	      used by a process to set the per-process	limit,	RLIMIT_NOFILE,
	      on  the  number of files it may open.)  If you get lots of error
	      messages in the kernel log about running	out  of	 file  handles
	      (look  for "VFS: file-max limit <number> reached"), try increas‐
	      ing this value:

		  echo 100000 > /proc/sys/fs/file-max

	      The kernel constant NR_OPEN imposes an upper limit on the	 value
	      that may be placed in file-max.

	      Privileged  processes  (CAP_SYS_ADMIN) can override the file-max
	      limit.

       /proc/sys/fs/file-nr
	      This (read-only) file contains  three  numbers:  the  number  of
	      allocated	 file  handles	(i.e.,	the  number of files presently
	      opened); the number of free file handles; and the maximum number
	      of file handles (i.e., the same value as /proc/sys/fs/file-max).
	      If the number of allocated file handles is close to the maximum,
	      you  should  consider increasing the maximum.  Before Linux 2.6,
	      the kernel allocated file handles	 dynamically,  but  it	didn't
	      free  them  again.  Instead the free file handles were kept in a
	      list for reallocation; the "free file handles"  value  indicates
	      the  size	 of  that  list.   A large number of free file handles
	      indicates that there was a past peak in the usage of  open  file
	      handles.	Since Linux 2.6, the kernel does deallocate freed file
	      handles, and the "free file handles" value is always zero.

       /proc/sys/fs/inode-max (only present until Linux 2.2)
	      This file contains the maximum number of in-memory inodes.  This
	      value  should  be	 3-4  times larger than the value in file-max,
	      since stdin, stdout and network sockets also need	 an  inode  to
	      handle  them.  When you regularly run out of inodes, you need to
	      increase this value.

	      Starting with Linux 2.4, there is no longer a  static  limit  on
	      the number of inodes, and this file is removed.

       /proc/sys/fs/inode-nr
	      This file contains the first two values from inode-state.

       /proc/sys/fs/inode-state
	      This  file  contains  seven  numbers: nr_inodes, nr_free_inodes,
	      preshrink, and four dummy values (always zero).

	      nr_inodes is the number of  inodes  the  system  has  allocated.
	      nr_free_inodes represents the number of free inodes.

	      preshrink is nonzero when the nr_inodes > inode-max and the sys‐
	      tem needs to prune the inode list instead	 of  allocating	 more;
	      since Linux 2.4, this field is a dummy value (always zero).

       /proc/sys/fs/inotify (since Linux 2.6.13)
	      This     directory     contains	  files	    max_queued_events,
	      max_user_instances, and max_user_watches, that can  be  used  to
	      limit the amount of kernel memory consumed by the inotify inter‐
	      face.  For further details, see inotify(7).

       /proc/sys/fs/lease-break-time
	      This file specifies the grace period that the kernel grants to a
	      process holding a file lease (fcntl(2)) after it has sent a sig‐
	      nal to that process notifying it that another process is waiting
	      to  open the file.  If the lease holder does not remove or down‐
	      grade the lease within this grace period,	 the  kernel  forcibly
	      breaks the lease.

       /proc/sys/fs/leases-enable
	      This  file  can  be  used	 to  enable  or	 disable  file	leases
	      (fcntl(2)) on a system-wide basis.  If this  file	 contains  the
	      value 0, leases are disabled.  A nonzero value enables leases.

       /proc/sys/fs/mqueue (since Linux 2.6.6)
	      This   directory	 contains   files  msg_max,  msgsize_max,  and
	      queues_max, controlling the  resources  used  by	POSIX  message
	      queues.  See mq_overview(7) for details.

       /proc/sys/fs/overflowgid and /proc/sys/fs/overflowuid
	      These  files  allow you to change the value of the fixed UID and
	      GID.  The default	 is  65534.   Some  filesystems	 support  only
	      16-bit  UIDs  and	 GIDs,	although in Linux UIDs and GIDs are 32
	      bits.  When one of these	filesystems  is	 mounted  with	writes
	      enabled, any UID or GID that would exceed 65535 is translated to
	      the overflow value before being written to disk.

       /proc/sys/fs/pipe-max-size (since Linux 2.6.35)
	      The value in this file defines an upper limit  for  raising  the
	      capacity	of  a  pipe using the fcntl(2) F_SETPIPE_SZ operation.
	      This limit applies only to unprivileged processes.  The  default
	      value  for  this	file is 1,048,576.  The value assigned to this
	      file may be  rounded  upward,  to	 reflect  the  value  actually
	      employed	for  a	convenient  implementation.   To determine the
	      rounded-up value,	 display  the  contents	 of  this  file	 after
	      assigning a value to it.	The minimum value that can be assigned
	      to this file is the system page size.

       /proc/sys/fs/protected_hardlinks (since Linux 3.6)
	      When the value in this file is 0, no restrictions are placed  on
	      the  creation of hard links (i.e., this is the historical behav‐
	      iour before Linux 3.6).  When the value in this  file  is	 1,  a
	      hard  link  can  be  created to a target file only if one of the
	      following conditions is true:

	      *	 The caller has the CAP_FOWNER capability.

	      *	 The filesystem UID of the process creating the	 link  matches
		 the  owner  (UID) of the target file (as described in creden‐
		 tials(7), a process's filesystem UID is normally the same  as
		 its effective UID).

	      *	 All of the following conditions are true:

		  ·  the target is a regular file;

		  ·  the  target file does not have its set-user-ID permission
		     bit enabled;

		  ·  the target file does not have both its  set-group-ID  and
		     group-executable permission bits enabled; and

		  ·  the  caller  has  permission to read and write the target
		     file (either via the file's permissions mask  or  because
		     it has suitable capabilities).

	      The  default  value  in  this file is 0.	Setting the value to 1
	      prevents a longstanding class of security issues caused by hard-
	      link-based  time-of-check, time-of-use races, most commonly seen
	      in world-writable directories such as /tmp.  The	common	method
	      of  exploiting  this  flaw is to cross privilege boundaries when
	      following a given hard link (i.e., a root process follows a hard
	      link created by another user).  Additionally, on systems without
	      separated partitions, this stops unauthorized users  from	 "pin‐
	      ning"  vulnerable	 set-user-ID  and  set-group-ID	 files against
	      being upgraded by	 the  administrator,  or  linking  to  special
	      files.

       /proc/sys/fs/protected_symlinks (since Linux 3.6)
	      When  the value in this file is 0, no restrictions are placed on
	      following symbolic links (i.e., this is the historical behaviour
	      before  Linux  3.6).  When the value in this file is 1, symbolic
	      links are followed only in the following circumstances:

	      *	 the filesystem UID of the process following the link  matches
		 the owner (UID) of the symbolic link (as described in creden‐
		 tials(7), a process's filesystem UID is normally the same  as
		 its effective UID);

	      *	 the link is not in a sticky world-writable directory; or

	      *	 the  symbolic	link  and  its	parent directory have the same
		 owner (UID)

	      A system call that fails to follow a symbolic  link  because  of
	      the above restrictions returns the error EACCES in errno.

	      The  default  value  in  this file is 0.	Setting the value to 1
	      avoids a longstanding class of security issues based on time-of-
	      check, time-of-use races when accessing symbolic links.

       /proc/sys/fs/suid_dumpable (since Linux 2.6.13)
	      The  value  in  this file determines whether core dump files are
	      produced for set-user-ID or  otherwise  protected/tainted	 bina‐
	      ries.  Three different integer values can be specified:

	      0 (default)
		     This  provides  the traditional (pre-Linux 2.6.13) behav‐
		     ior.  A core dump will not	 be  produced  for  a  process
		     which  has	 changed  credentials  (by calling seteuid(2),
		     setgid(2), or similar, or by executing a  set-user-ID  or
		     set-group-ID  program) or whose binary does not have read
		     permission enabled.

	      1 ("debug")
		     All processes dump core when possible.  The core dump  is
		     owned  by	the  filesystem user ID of the dumping process
		     and no security is applied.  This is intended for	system
		     debugging situations only.	 Ptrace is unchecked.

	      2 ("suidsafe")
		     Any  binary  which	 normally would not be dumped (see "0"
		     above) is dumped readable by root only.  This allows  the
		     user  to  remove  the  core dump file but not to read it.
		     For security reasons core dumps in	 this  mode  will  not
		     overwrite	one  another  or  other	 files.	  This mode is
		     appropriate when administrators are attempting  to	 debug
		     problems in a normal environment.

		     Additionally, since Linux 3.6, /proc/sys/kernel/core_pat‐
		     tern must either be an absolute pathname or a  pipe  com‐
		     mand,  as	detailed in core(5).  Warnings will be written
		     to the kernel log if core_pattern does not	 follow	 these
		     rules, and no core dump will be produced.

       /proc/sys/fs/super-max
	      This  file  controls the maximum number of superblocks, and thus
	      the maximum number of mounted filesystems the kernel  can	 have.
	      You  need	 increase  only	 super-max  if	you need to mount more
	      filesystems than the current value in super-max allows you to.

       /proc/sys/fs/super-nr
	      This file contains the number of filesystems currently mounted.

       /proc/sys/kernel
	      This directory contains files  controlling  a  range  of	kernel
	      parameters, as described below.

       /proc/sys/kernel/acct
	      This  file contains three numbers: highwater, lowwater, and fre‐
	      quency.  If BSD-style process accounting is enabled, these  val‐
	      ues control its behavior.	 If free space on filesystem where the
	      log lives goes below lowwater percent, accounting suspends.   If
	      free  space  gets	 above	highwater percent, accounting resumes.
	      frequency determines how often the kernel checks the  amount  of
	      free  space  (value is in seconds).  Default values are 4, 2 and
	      30.  That is, suspend accounting if 2% or less  space  is	 free;
	      resume  it  if  4%  or  more space is free; consider information
	      about amount of free space valid for 30 seconds.

       /proc/sys/kernel/cap_last_cap (since Linux 3.2)
	      See capabilities(7).

       /proc/sys/kernel/cap-bound (from Linux 2.2 to 2.6.24)
	      This file holds the value of the kernel capability bounding  set
	      (expressed  as  a	 signed	 decimal  number).   This set is ANDed
	      against  the  capabilities  permitted  to	  a   process	during
	      execve(2).  Starting with Linux 2.6.25, the system-wide capabil‐
	      ity bounding set disappeared, and was replaced by	 a  per-thread
	      bounding set; see capabilities(7).

       /proc/sys/kernel/core_pattern
	      See core(5).

       /proc/sys/kernel/core_uses_pid
	      See core(5).

       /proc/sys/kernel/ctrl-alt-del
	      This  file  controls  the handling of Ctrl-Alt-Del from the key‐
	      board.  When the value  in  this	file  is  0,  Ctrl-Alt-Del  is
	      trapped  and  sent  to  the init(8) program to handle a graceful
	      restart.	When the value is greater than zero, Linux's  reaction
	      to  a Vulcan Nerve Pinch (tm) will be an immediate reboot, with‐
	      out even syncing its dirty buffers.  Note: when a program	 (like
	      dosemu)  has  the	 keyboard  in  "raw" mode, the ctrl-alt-del is
	      intercepted by the program before it ever reaches the kernel tty
	      layer, and it's up to the program to decide what to do with it.

       /proc/sys/kernel/dmesg_restrict (since Linux 2.6.37)
	      The value in this file determines who can see kernel syslog con‐
	      tents.  A value of 0 in this file imposes no  restrictions.   If
	      the  value  is 1, only privileged users can read the kernel sys‐
	      log.  (See syslog(2) for more details.)  Since Linux  3.4,  only
	      users  with the CAP_SYS_ADMIN capability may change the value in
	      this file.

       /proc/sys/kernel/domainname and /proc/sys/kernel/hostname
	      can be used to set the NIS/YP domainname	and  the  hostname  of
	      your  box	 in exactly the same way as the commands domainname(1)
	      and hostname(1), that is:

		  # echo 'darkstar' > /proc/sys/kernel/hostname
		  # echo 'mydomain' > /proc/sys/kernel/domainname

	      has the same effect as

		  # hostname 'darkstar'
		  # domainname 'mydomain'

	      Note, however, that the classic darkstar.frop.org has the	 host‐
	      name "darkstar" and DNS (Internet Domain Name Server) domainname
	      "frop.org", not to be confused with the NIS (Network Information
	      Service)	or  YP	(Yellow	 Pages)	 domainname.  These two domain
	      names are in general different.  For a detailed  discussion  see
	      the hostname(1) man page.

       /proc/sys/kernel/hotplug
	      This  file  contains the path for the hotplug policy agent.  The
	      default value in this file is /sbin/hotplug.

       /proc/sys/kernel/htab-reclaim
	      (PowerPC only) If this file is set to a nonzero value, the  Pow‐
	      erPC  htab  (see kernel file Documentation/powerpc/ppc_htab.txt)
	      is pruned each time the system hits the idle loop.

       /proc/sys/kernel/kptr_restrict (since Linux 2.6.38)
	      The value in this file determines whether kernel	addresses  are
	      exposed  via  /proc files and other interfaces.  A value of 0 in
	      this file imposes no restrictions.  If the value	is  1,	kernel
	      pointers printed using the %pK format specifier will be replaced
	      with zeros unless the user has the  CAP_SYSLOG  capability.   If
	      the  value  is  2,  kernel pointers printed using the %pK format
	      specifier will be replaced with zeros regardless of  the	user's
	      capabilities.   The  initial  default value for this file was 1,
	      but the default was changed to 0 in Linux 2.6.39.	  Since	 Linux
	      3.4, only users with the CAP_SYS_ADMIN capability can change the
	      value in this file.

       /proc/sys/kernel/l2cr
	      (PowerPC only) This file contains a flag that  controls  the  L2
	      cache  of	 G3  processor	boards.	  If 0, the cache is disabled.
	      Enabled if nonzero.

       /proc/sys/kernel/modprobe
	      This file contains the path for the kernel module	 loader.   The
	      default  value  is  /sbin/modprobe.  The file is present only if
	      the kernel is built  with	 the  CONFIG_MODULES  (CONFIG_KMOD  in
	      Linux  2.6.26  and  earlier) option enabled.  It is described by
	      the Linux kernel	source	file  Documentation/kmod.txt  (present
	      only in kernel 2.4 and earlier).

       /proc/sys/kernel/modules_disabled (since Linux 2.6.31)
	      A toggle value indicating if modules are allowed to be loaded in
	      an otherwise modular kernel.  This toggle defaults to  off  (0),
	      but  can	be  set	 true  (1).  Once true, modules can be neither
	      loaded nor unloaded, and the toggle cannot be set back to false.
	      The  file	 is  present only if the kernel is built with the CON‐
	      FIG_MODULES option enabled.

       /proc/sys/kernel/msgmax (since Linux 2.2)
	      This file defines a system-wide  limit  specifying  the  maximum
	      number  of  bytes in a single message written on a System V mes‐
	      sage queue.

       /proc/sys/kernel/msgmni (since Linux 2.4)
	      This file defines the system-wide limit on the number of message
	      queue identifiers.

       /proc/sys/kernel/msgmnb (since Linux 2.2)
	      This file defines a system-wide parameter used to initialize the
	      msg_qbytes setting for subsequently created message queues.  The
	      msg_qbytes  setting  specifies  the maximum number of bytes that
	      may be written to the message queue.

       /proc/sys/kernel/ngroups_max (since Linux 2.6.4)
	      This is a read-only file that displays the upper	limit  on  the
	      number of a process's group memberships.

       /proc/sys/kernel/ostype and /proc/sys/kernel/osrelease
	      These files give substrings of /proc/version.

       /proc/sys/kernel/overflowgid and /proc/sys/kernel/overflowuid
	      These  files  duplicate  the  files /proc/sys/fs/overflowgid and
	      /proc/sys/fs/overflowuid.

       /proc/sys/kernel/panic
	      This  file  gives	 read/write  access  to	 the  kernel  variable
	      panic_timeout.   If  this	 is  zero,  the	 kernel will loop on a
	      panic; if nonzero, it indicates that the kernel  should  autore‐
	      boot  after  this	 number of seconds.  When you use the software
	      watchdog device driver, the recommended setting is 60.

       /proc/sys/kernel/panic_on_oops (since Linux 2.5.68)
	      This file controls the kernel's behavior when an oops or BUG  is
	      encountered.   If this file contains 0, then the system tries to
	      continue operation.  If it contains 1, then the system delays  a
	      few  seconds  (to give klogd time to record the oops output) and
	      then  panics.   If  the  /proc/sys/kernel/panic  file  is	  also
	      nonzero, then the machine will be rebooted.

       /proc/sys/kernel/pid_max (since Linux 2.5.34)
	      This  file  specifies the value at which PIDs wrap around (i.e.,
	      the value in this file is one greater  than  the	maximum	 PID).
	      The  default  value  for	this  file, 32768, results in the same
	      range of PIDs as on earlier kernels.  On 32-bit platforms, 32768
	      is  the  maximum	value for pid_max.  On 64-bit systems, pid_max
	      can be set to any value up to 2^22 (PID_MAX_LIMIT, approximately
	      4 million).

       /proc/sys/kernel/powersave-nap (PowerPC only)
	      This file contains a flag.  If set, Linux-PPC will use the "nap"
	      mode of powersaving, otherwise the "doze" mode will be used.

       /proc/sys/kernel/printk
	      The four values in this file are console_loglevel,  default_mes‐
	      sage_loglevel,	 minimum_console_level,	   and	  default_con‐
	      sole_loglevel.  These values influence  printk()	behavior  when
	      printing or logging error messages.  See syslog(2) for more info
	      on the different loglevels.  Messages  with  a  higher  priority
	      than  console_loglevel will be printed to the console.  Messages
	      without an explicit  priority  will  be  printed	with  priority
	      default_message_level.   minimum_console_loglevel is the minimum
	      (highest)	 value	to  which   console_loglevel   can   be	  set.
	      default_console_loglevel	 is   the   default   value  for  con‐
	      sole_loglevel.

       /proc/sys/kernel/pty (since Linux 2.6.4)
	      This directory contains two files relating to the number of UNIX
	      98 pseudoterminals (see pts(4)) on the system.

       /proc/sys/kernel/pty/max
	      This file defines the maximum number of pseudoterminals.

       /proc/sys/kernel/pty/nr
	      This  read-only file indicates how many pseudoterminals are cur‐
	      rently in use.

       /proc/sys/kernel/random
	      This directory contains various parameters controlling the oper‐
	      ation of the file /dev/random.  See random(4) for further infor‐
	      mation.

       /proc/sys/kernel/random/uuid (since Linux 2.4)
	      Each read from this read-only file returns a randomly  generated
	      128-bit UUID, as a string in the standard UUID format.

       /proc/sys/kernel/real-root-dev
	      This file is documented in the Linux kernel source file Documen‐
	      tation/initrd.txt.

       /proc/sys/kernel/reboot-cmd (Sparc only)
	      This file seems to be a way to give an  argument	to  the	 SPARC
	      ROM/Flash	 boot  loader.	 Maybe	to  tell  it  what to do after
	      rebooting?

       /proc/sys/kernel/rtsig-max
	      (Only in kernels up to and including  2.6.7;  see	 setrlimit(2))
	      This  file can be used to tune the maximum number of POSIX real-
	      time (queued) signals that can be outstanding in the system.

       /proc/sys/kernel/rtsig-nr
	      (Only in kernels up to and including 2.6.7.)   This  file	 shows
	      the number POSIX real-time signals currently queued.

       /proc/sys/kernel/sched_rr_timeslice_ms (since Linux 3.9)
	      See sched_rr_get_interval(2).

       /proc/sys/kernel/sem (since Linux 2.4)
	      This  file  contains  4 numbers defining limits for System V IPC
	      semaphores.  These fields are, in order:

	      SEMMSL  The maximum semaphores per semaphore set.

	      SEMMNS  A system-wide limit on the number of semaphores  in  all
		      semaphore sets.

	      SEMOPM  The  maximum  number of operations that may be specified
		      in a semop(2) call.

	      SEMMNI  A system-wide limit on the maximum number	 of  semaphore
		      identifiers.

       /proc/sys/kernel/sg-big-buff
	      This file shows the size of the generic SCSI device (sg) buffer.
	      You can't tune it just yet, but you could change it  at  compile
	      time  by	editing	 include/scsi/sg.h  and	 changing the value of
	      SG_BIG_BUFF.  However, there shouldn't be any reason  to	change
	      this value.

       /proc/sys/kernel/shm_rmid_forced (since Linux 3.1)
	      If  this	file  is set to 1, all System V shared memory segments
	      will be marked for destruction as soon as the number of attached
	      processes	 falls to zero; in other words, it is no longer possi‐
	      ble to create shared memory segments that exist independently of
	      any attached process.

	      The effect is as though a shmctl(2) IPC_RMID is performed on all
	      existing	segments as well as all segments created in the future
	      (until  this  file  is reset to 0).  Note that existing segments
	      that are attached to no process will  be	immediately  destroyed
	      when  this  file	is  set	 to  1.	 Setting this option will also
	      destroy segments that were created,  but	never  attached,  upon
	      termination  of  the  process  that  created  the	 segment  with
	      shmget(2).

	      Setting this file to 1 provides a way of ensuring that all  Sys‐
	      tem  V  shared  memory segments are counted against the resource
	      usage and resource limits (see the description of	 RLIMIT_AS  in
	      getrlimit(2)) of at least one process.

	      Because  setting	this  file to 1 produces behavior that is non‐
	      standard and could also break existing applications, the default
	      value  in this file is 0.	 Only set this file to 1 if you have a
	      good understanding of the semantics of  the  applications	 using
	      System V shared memory on your system.

       /proc/sys/kernel/shmall (since Linux 2.2)
	      This  file contains the system-wide limit on the total number of
	      pages of System V shared memory.

       /proc/sys/kernel/shmmax (since Linux 2.2)
	      This file can be used to query and set the run-time limit on the
	      maximum  (System	V  IPC) shared memory segment size that can be
	      created.	Shared memory segments up to 1GB are now supported  in
	      the kernel.  This value defaults to SHMMAX.

       /proc/sys/kernel/shmmni (since Linux 2.4)
	      This  file  specifies the system-wide maximum number of System V
	      shared memory segments that can be created.

       /proc/sys/kernel/sysrq
	      This file controls the functions allowed to be  invoked  by  the
	      SysRq  key.   By default, the file contains 1 meaning that every
	      possible SysRq request is allowed	 (in  older  kernel  versions,
	      SysRq was disabled by default, and you were required to specifi‐
	      cally enable it at run-time, but this is not the case any more).
	      Possible values in this file are:

		 0 - disable sysrq completely
		 1 - enable all functions of sysrq
		>1 - bit mask of allowed sysrq functions, as follows:
			2 - enable control of console logging level
			4 - enable control of keyboard (SAK, unraw)
			8 - enable debugging dumps of processes etc.
		       16 - enable sync command
		       32 - enable remount read-only
		       64  -  enable  signaling of processes (term, kill, oom-
	      kill)
		      128 - allow reboot/poweroff
		      256 - allow nicing of all real-time tasks

	      This file is present only if the CONFIG_MAGIC_SYSRQ kernel  con‐
	      figuration option is enabled.  For further details see the Linux
	      kernel source file Documentation/sysrq.txt.

       /proc/sys/kernel/version
	      This file contains a string like:

		  #5 Wed Feb 25 21:49:24 MET 1998

	      The "#5" means that this is the fifth  kernel  built  from  this
	      source base and the date behind it indicates the time the kernel
	      was built.

       /proc/sys/kernel/threads-max (since Linux 2.3.11)
	      This file specifies the  system-wide  limit  on  the  number  of
	      threads (tasks) that can be created on the system.

       /proc/sys/kernel/zero-paged (PowerPC only)
	      This  file  contains  a flag.  When enabled (nonzero), Linux-PPC
	      will pre-zero pages in  the  idle	 loop,	possibly  speeding  up
	      get_free_pages.

       /proc/sys/net
	      This directory contains networking stuff.	 Explanations for some
	      of the files under this directory can be	found  in  tcp(7)  and
	      ip(7).

       /proc/sys/net/core/somaxconn
	      This  file  defines  a ceiling value for the backlog argument of
	      listen(2); see the listen(2) manual page for details.

       /proc/sys/proc
	      This directory may be empty.

       /proc/sys/sunrpc
	      This directory supports Sun remote procedure  call  for  network
	      filesystem (NFS).	 On some systems, it is not present.

       /proc/sys/vm
	      This directory contains files for memory management tuning, buf‐
	      fer and cache management.

       /proc/sys/vm/drop_caches (since Linux 2.6.16)
	      Writing to this file causes the kernel  to  drop	clean  caches,
	      dentries,	 and inodes from memory, causing that memory to become
	      free.  This can be useful for memory management testing and per‐
	      forming  reproducible filesystem benchmarks.  Because writing to
	      this file causes the benefits of caching	to  be	lost,  it  can
	      degrade overall system performance.

	      To free pagecache, use:

		  echo 1 > /proc/sys/vm/drop_caches

	      To free dentries and inodes, use:

		  echo 2 > /proc/sys/vm/drop_caches

	      To free pagecache, dentries and inodes, use:

		  echo 3 > /proc/sys/vm/drop_caches

	      Because  writing	to this file is a nondestructive operation and
	      dirty objects are not freeable,  the  user  should  run  sync(8)
	      first.

       /proc/sys/vm/legacy_va_layout (since Linux 2.6.9)
	      If  nonzero, this disables the new 32-bit memory-mapping layout;
	      the kernel will use the legacy (2.4) layout for all processes.

       /proc/sys/vm/memory_failure_early_kill (since Linux 2.6.32)
	      Control how to kill processes when an uncorrected	 memory	 error
	      (typically a 2-bit error in a memory module) that cannot be han‐
	      dled by the kernel is detected in the  background	 by  hardware.
	      In some cases (like the page still having a valid copy on disk),
	      the kernel will handle the failure transparently without affect‐
	      ing  any applications.  But if there is no other up-to-date copy
	      of the data, it will kill processes to prevent any data  corrup‐
	      tions from propagating.

	      The file has one of the following values:

	      1:  Kill	all  processes that have the corrupted-and-not-reload‐
		  able page mapped as soon  as	the  corruption	 is  detected.
		  Note	this  is  not supported for a few types of pages, like
		  kernel internally allocated data  or	the  swap  cache,  but
		  works for the majority of user pages.

	      0:  Only	unmap  the  corrupted page from all processes and kill
		  only a process that tries to access it.

	      The kill is performed using a SIGBUS signal with si_code set  to
	      BUS_MCEERR_AO.   Processes  can handle this if they want to; see
	      sigaction(2) for more details.

	      This feature is  active  only  on	 architectures/platforms  with
	      advanced	machine	 check	handling  and  depends on the hardware
	      capabilities.

	      Applications can override the memory_failure_early_kill  setting
	      individually with the prctl(2) PR_MCE_KILL operation.

	      Only  present  if	 the  kernel  was  configured with CONFIG_MEM‐
	      ORY_FAILURE.

       /proc/sys/vm/memory_failure_recovery (since Linux 2.6.32)
	      Enable memory failure recovery (when supported by the platform)

	      1:  Attempt recovery.

	      0:  Always panic on a memory failure.

	      Only present if  the  kernel  was	 configured  with  CONFIG_MEM‐
	      ORY_FAILURE.

       /proc/sys/vm/oom_dump_tasks (since Linux 2.6.25)
	      Enables a system-wide task dump (excluding kernel threads) to be
	      produced when the kernel	performs  an  OOM-killing.   The  dump
	      includes	the  following	information  for  each	task  (thread,
	      process): thread ID, real user ID, thread group ID (process ID),
	      virtual memory size, resident set size, the CPU that the task is
	      scheduled	 on,   oom_adj	 score	 (see	the   description   of
	      /proc/[pid]/oom_adj),  and  command  name.   This	 is helpful to
	      determine why the OOM-killer was invoked	and  to	 identify  the
	      rogue task that caused it.

	      If this contains the value zero, this information is suppressed.
	      On very large systems with thousands of tasks,  it  may  not  be
	      feasible	to  dump  the  memory  state information for each one.
	      Such systems should not be forced to incur a performance penalty
	      in OOM situations when the information may not be desired.

	      If  this	is  set to nonzero, this information is shown whenever
	      the OOM-killer actually kills a memory-hogging task.

	      The default value is 0.

       /proc/sys/vm/oom_kill_allocating_task (since Linux 2.6.24)
	      This enables or disables killing the OOM-triggering task in out-
	      of-memory situations.

	      If  this	is  set	 to zero, the OOM-killer will scan through the
	      entire tasklist and select a task based on heuristics  to	 kill.
	      This  normally selects a rogue memory-hogging task that frees up
	      a large amount of memory when killed.

	      If this is set to nonzero, the OOM-killer simply kills the  task
	      that  triggered the out-of-memory condition.  This avoids a pos‐
	      sibly expensive tasklist scan.

	      If /proc/sys/vm/panic_on_oom is  nonzero,	 it  takes  precedence
	      over  whatever  value  is used in /proc/sys/vm/oom_kill_allocat‐
	      ing_task.

	      The default value is 0.

       /proc/sys/vm/overcommit_memory
	      This file contains the kernel virtual  memory  accounting	 mode.
	      Values are:

		     0: heuristic overcommit (this is the default)
		     1: always overcommit, never check
		     2: always check, never overcommit

	      In  mode 0, calls of mmap(2) with MAP_NORESERVE are not checked,
	      and the default check is very weak, leading to the risk of  get‐
	      ting  a process "OOM-killed".  Under Linux 2.4 any nonzero value
	      implies mode 1.  In mode 2  (available  since  Linux  2.6),  the
	      total  virtual  address  space on the system is limited to (SS +
	      RAM*(r/100)), where SS is the size of the swap space, and RAM is
	      the  size	 of  the physical memory, and r is the contents of the
	      file /proc/sys/vm/overcommit_ratio.

       /proc/sys/vm/overcommit_ratio
	      See the description of /proc/sys/vm/overcommit_memory.

       /proc/sys/vm/panic_on_oom (since Linux 2.6.18)
	      This enables or disables a kernel panic in an out-of-memory sit‐
	      uation.

	      If this file is set to the value 0, the kernel's OOM-killer will
	      kill some rogue process.	Usually, the  OOM-killer  is  able  to
	      kill a rogue process and the system will survive.

	      If  this	file  is  set to the value 1, then the kernel normally
	      panics when out-of-memory happens.  However, if a process limits
	      allocations  to  certain	nodes  using memory policies (mbind(2)
	      MPOL_BIND) or cpusets (cpuset(7)) and those nodes	 reach	memory
	      exhaustion  status, one process may be killed by the OOM-killer.
	      No panic occurs in this case: because other nodes' memory may be
	      free,  this  means the system as a whole may not have reached an
	      out-of-memory situation yet.

	      If this file is set to the value 2,  the	kernel	always	panics
	      when an out-of-memory condition occurs.

	      The default value is 0.  1 and 2 are for failover of clustering.
	      Select either according to your policy of failover.

       /proc/sys/vm/swappiness
	      The value in this file controls how aggressively the kernel will
	      swap memory pages.  Higher values increase aggressiveness, lower
	      values decrease aggressiveness.  The default value is 60.

       /proc/sysrq-trigger (since Linux 2.4.21)
	      Writing a character to this file triggers the same  SysRq	 func‐
	      tion  as	typing	ALT-SysRq-<character>  (see the description of
	      /proc/sys/kernel/sysrq).	This file is normally writable only by
	      root.  For further details see the Linux kernel source file Doc‐
	      umentation/sysrq.txt.

       /proc/sysvipc
	      Subdirectory containing  the  pseudo-files  msg,	sem  and  shm.
	      These  files  list the System V Interprocess Communication (IPC)
	      objects (respectively: message queues,  semaphores,  and	shared
	      memory)  that  currently	exist on the system, providing similar
	      information to that available via	 ipcs(1).   These  files  have
	      headers  and  are	 formatted  (one IPC object per line) for easy
	      understanding.  svipc(7)	provides  further  background  on  the
	      information shown by these files.

       /proc/tty
	      Subdirectory  containing the pseudo-files and subdirectories for
	      tty drivers and line disciplines.

       /proc/uptime
	      This file contains two numbers: the uptime of the	 system	 (sec‐
	      onds), and the amount of time spent in idle process (seconds).

       /proc/version
	      This string identifies the kernel version that is currently run‐
	      ning.  It	 includes  the	contents  of  /proc/sys/kernel/ostype,
	      /proc/sys/kernel/osrelease  and  /proc/sys/kernel/version.   For
	      example:
	    Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994

       /proc/vmstat (since Linux 2.6)
	      This file displays various virtual memory statistics.

       /proc/zoneinfo (since Linux 2.6.13)
	      This file display information about memory zones.	 This is  use‐
	      ful for analyzing virtual memory behavior.

NOTES
       Many strings (i.e., the environment and command line) are in the inter‐
       nal format, with subfields terminated by null bytes ('\0'), so you  may
       find  that  things are more readable if you use od -c or tr "\000" "\n"
       to read them.  Alternatively, echo `cat <file>` works well.

       This manual page is incomplete, possibly inaccurate, and is the kind of
       thing that needs to be updated very often.

SEE ALSO
       cat(1), dmesg(1), find(1), free(1), ps(1), tr(1), uptime(1), chroot(2),
       mmap(2), readlink(2), syslog(2), slabinfo(5), hier(7), time(7), arp(8),
       hdparm(8),  ifconfig(8),	 init(8),  lsmod(8),  lspci(8), mount(8), net‐
       stat(8), procinfo(8), route(8), sysctl(8)

       The Linux kernel source files: Documentation/filesystems/proc.txt Docu‐
       mentation/sysctl/fs.txt,	  Documentation/sysctl/kernel.txt,  Documenta‐
       tion/sysctl/net.txt, and Documentation/sysctl/vm.txt.

COLOPHON
       This page is part of release 3.65 of the Linux  man-pages  project.   A
       description  of	the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux				  2014-04-12			       PROC(5)
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