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PROC(5) 		   Linux Programmers Manual		      PROC(5)

       proc - process information pseudo-file system

       The proc file system is a pseudo-file system which is used as an inter
       face to kernel data structures.	It is commonly mounted at /proc.  Most
       of  it  is  read-only,  but  some  files  allow	kernel variables to be

       The following outline gives a quick tour through the /proc hierarchy.

	      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/[number]/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.

	      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 null-separated strings, with a further null byte ('\0') after
	      the last string.

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

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

	      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)).

	      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:

		  (cat /proc/1/environ; echo) | tr "\000" "\n"

	      (For a reason why one should want to do  this,  see  lilo(8)  or

	      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/[number]/exe  to
	      run  another copy of the same executable as is being run by pro
	      cess [number].  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)).

	      Under Linux 2.0 and earlier /proc/[number]/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:


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

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

	      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, etc.

	      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/[number]/fd.  For example,
	      assuming 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

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

       /proc/[number]/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/[number]/limits (since kernel 2.6.24)
	      This file displays the soft limit, hard limit, and units of mea
	      surement	for  each  of the processs resource limits (see getr
	      limit(2)).  The file is protected to only allow reading  by  the
	      real UID of the process.

	      A  file containing the currently mapped memory regions and their
	      access permissions.

	      The format is:

	address 	  perms offset	dev   inode	 pathname
	08048000-08056000 r-xp 00000000 03:0c 64593	 /usr/sbin/gpm
	08056000-08058000 rw-p 0000d000 03:0c 64593	 /usr/sbin/gpm
	08058000-0805b000 rwxp 00000000 00:00 0
	40000000-40013000 r-xp 00000000 03:0c 4165	 /lib/ld-2.2.4.so
	40013000-40015000 rw-p 00012000 03:0c 4165	 /lib/ld-2.2.4.so
	4001f000-40135000 r-xp 00000000 03:0c 45494	 /lib/libc-2.2.4.so
	40135000-4013e000 rw-p 00115000 03:0c 45494	 /lib/libc-2.2.4.so
	4013e000-40142000 rw-p 00000000 00:00 0
	bffff000-c0000000 rwxp 00000000 00:00 0

	      where "address" is the address space  in	the  process  that  it
	      occupies, "perms" is a set of permissions:

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

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

	      Under Linux 2.0 there is no field giving pathname.

	      This file can be used to access the pages of a processs  memory
	      through open(2), read(2), and lseek(2).

       /proc/[number]/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

		   (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 file system
			(see stat(2)).

		   (4)	root: root of the mount within the file system.

		   (5)	mount point: mount point  relative  to	the  processs

		   (6)	mount options: per-mount options.

		   (7)	optional  fields:  zero  or  more  fields  of the form

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

		   (9)	file system type: name of  file  system  in  the  form

		   (10) mount  source:	file  system-specific  information  or

		   (11) super options: per-super block 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  processs
	      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 kernel source tree.

       /proc/[number]/mountstats (since Linux 2.6.17)
	      This file system exports information (statistics,  configuration
	      information) about the mount points in the processs 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 file system tree.

		   (3)	The file system type.

		   (4)	Optional  statistics  and  configuration  information.
			Currently (as at Linux 2.6.26), only NFS file  systems
			export information via this field.

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

       /proc/[number]/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 pro
	      cesss 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 parents oom_adj
	      setting.	A process must	be  privileged	(CAP_SYS_RESOURCE)  to
	      update this file.

       /proc/[number]/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 bit-shift  adjustment  specified
	      by the oom_adj setting for the process.

	      Unix  and  Linux	support  the idea of a per-process root of the
	      file system, set by the chroot(2) system call.  This file  is  a
	      symbolic	link  that points to the processs root directory, and
	      behaves as exe, fd/*, etc. do.

	      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/[number]/smaps (since Linux 2.6.14)
	      This file shows memory consumption for  each  of	the  processs
	      mappings.   For each of mappings there is a series of lines such
	      as the following:

		  08048000-080bc000 r-xp 00000000 03:02 13130	   /bin/bash
		  Size: 	      464 kB
		  Rss:		      424 kB
		  Shared_Clean:       424 kB
		  Shared_Dirty: 	0 kB
		  Private_Clean:	0 kB
		  Private_Dirty:	0 kB

	      The first of these lines shows the same information as  is  dis
	      played  for  the	mapping in /proc/[number]/maps.  The remaining
	      lines show the size of the mapping, the amount  of  the  mapping
	      that  is	currently  resident in RAM, the number clean and dirty
	      shared pages in the mapping, and the number clean and dirty pri
	      vate pages in the mapping.

	      This file is only present if the CONFIG_MMU kernel configuration
	      option is enabled.

	      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	  The process ID.

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

	      state %c	  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  zom
			  bie,	T is traced or stopped (on a signal), and W is

	      ppid %d	  The PID of the parent.

	      pgrp %d	  The process group ID of the process.

	      session %d  The session ID of the process.

	      tty_nr %d   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 t0 8.)

	      tpgid %d	  The  ID  of the foreground process group of the con
			  trolling terminal of the process.

	      flags %u (%lu before Linux 2.6.22)
			  The kernel flags word of the process.  For bit mean
			  ings,  see  the  PF_*  defines  in  .
			  Details depend on the kernel version.

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

	      cminflt %lu The  number  of  minor  faults  that	the  processs
			  waited-for children have made.

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

	      cmajflt %lu The  number  of  major  faults  that	the  processs
			  waited-for children have made.

	      utime %lu   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   Amount of time that this process has been  scheduled
			  in  kernel  mode, measured in clock ticks (divide by

	      cutime %ld  Amount of time that this processs waited-for	chil
			  dren	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

	      cstime %ld  Amount  of time that this processs waited-for chil
			  dren have been scheduled in kernel mode, measured in
			  clock ticks (divide by sysconf(_SC_CLK_TCK).

	      priority %ld
			  (Explanation	for Linux 2.6) For processes running a
			  real-time  scheduling  policy  (policy  below;   see
			  sched_setscheduler(2)), this is the negated schedul
			  ing priority, minus one; that is, a  number  in  the
			  range -2 to -100, corresponding to real-time priori
			  ties 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	  The nice value (see setpriority(2)), a value in  the
			  range 19 (low priority) to -20 (high priority).

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

	      starttime %llu (was %lu before Linux 2.6)
			  The time in jiffies the process started after system

	      vsize %lu   Virtual memory size in bytes.

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

	      rsslim %lu  Current  soft  limit in bytes on the rss of the pro
			  cess; see the description of RLIMIT_RSS in getprior

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

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

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

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

	      kstkeip %lu The current EIP (instruction pointer).

	      signal %lu  The  bitmap of pending signals, displayed as a deci
			  mal number.  Obsolete, because it does  not  provide
			  information  on  real-time  signals; use /proc/[num
			  ber]/status instead.

	      blocked %lu The bitmap of blocked signals, displayed as a  deci
			  mal  number.	 Obsolete, because it does not provide
			  information on real-time  signals;  use  /proc/[num
			  ber]/status instead.

	      sigignore %lu
			  The  bitmap of ignored signals, displayed as a deci
			  mal number.  Obsolete, because it does  not  provide
			  information  on  real-time  signals; use /proc/[num
			  ber]/status instead.

	      sigcatch %lu
			  The bitmap of caught signals, displayed as a decimal
			  number.   Obsolete,  because	it  does  not  provide
			  information on real-time  signals;  use  /proc/[num
			  ber]/status instead.

	      wchan %lu   This	is the "channel" in which the process is wait
			  ing.	It is the address of a system call, and can be
			  looked  up in a namelist if you need a textual name.
			  (If you have an up-to-date /etc/psdatabase, then try
			  ps -l to see the WCHAN field in action.)

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

	      cnswap %lu  Cumulative  nswap  for  child  processes  (not main

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

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

	      rt_priority %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
			  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

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

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

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

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

	      Provides information about memory usage, measured in pages.  The
	      columns are:

		  size	     total program size
			     (same as VmSize in /proc/[number]/status)
		  resident   resident set size
			     (same as VmRSS in /proc/[number]/status)
		  share      shared pages (from shared mappings)
		  text	     text (code)
		  lib	     library (unused in Linux 2.6)
		  data	     data + stack
		  dt	     dirty pages (unused in Linux 2.6)

	      Provides much of	the  information  in  /proc/[number]/stat  and
	      /proc/[number]/statm  in	a  format  thats easier for humans to
	      parse.  Heres 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)).

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

	      * Uid,  Gid:  Real,  effective,  saved set, and file system UIDs

	      * 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.

	      * 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.

	      * 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

	      * CapBnd: Capability Bounding  set  (since  kernel  2.6.26,  see

	      * 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/[number]/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 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/[number] directories.  For
	      attributes that are shared by all threads, the contents for each
	      of  the  files under the task/[thread-ID] subdirectories will be
	      the same as in the corresponding file in the parent  /proc/[num
	      ber]  directory  (e.g.,  in  a multithreaded process, all of the
	      task/[thread-ID]/cwd files will  have  the  same	value  as  the
	      /proc/[number]/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/[thread-ID] may have  different	values	(e.g.,
	      various  fields in each of the task/[thread-ID]/status files may
	      be different for each thread).

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

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

	      Contains subdirectories for installed busses.

	      Subdirectory  for  PCMCIA  devices  when CONFIG_PCMCIA is set at
	      kernel compilation time.


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

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

	      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), zgrep(1), etc.  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  only  provided  if the kernel is configured

	      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.

	      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 kernel source file Documentation/iostats.txt for further

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

	      Empty subdirectory.

	      List of the execution domains (ABI personalities).

	      Frame buffer information when CONFIG_FB is defined during kernel

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

	      Incidentally, this file may be used by  mount(8)	when  no  file
	      system  is  specified and it didnt manage to determine the file
	      system type.  Then file systems contained in this file are tried
	      (excepted those that are marked with "nodev").

	      Empty subdirectory.

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

		  cache 	     buffer size in KB
		  capacity	     number of sectors
		  driver	     driver version
		  geometry	     physical and logical geometry
		  identify	     in hexadecimal
		  media 	     media type
		  model 	     manufacturers 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.

	      This is used to record the number of interrupts for each IRQ  on
	      (at least) the i386 architecture.  Very easy to read formatting,
	      done in ASCII.

	      I/O memory map in Linux 2.4.

	      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.

	      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.

	      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

	      Information in this file is retrieved with the dmesg(8) program.

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

	      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   executing   kernel   scheduling	 entities  (processes,
	      threads); this will be less than or equal to the number of CPUs.
	      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

	      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  only  present if CONFIG_DEBUG_MALLOC was defined
	      during compilation.

	      This is used by free(1) to report the amount of  free  and  used
	      memory  (both  physical  and  swap) on the system as well as the
	      shared memory and buffers used by the kernel.

	      It is in the same format as free(1).

	      This is a list of all the file systems currently mounted on  the
	      system.	The  format  of  this  file is documented in fstab(5).
	      Since kernel version 2.6.15, this file is pollable: after  open
	      ing  the	file  for reading, a change in this file (i.e., a file
	      system 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.

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

	      Memory  Type  Range  Registers.	See  /usr/src/linux/Documenta
	      tion/mtrr.txt for details.

	      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

	      This holds an ASCII readable dump of the kernel ARP  table  used
	      for  address resolutions.  It will show both dynamically learned
	      and pre-programmed ARP entries.  The format is:

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

	      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

	      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

	      Internet	  Group    Management	 Protocol.	Defined     in

	      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.

	      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

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

	      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.

	      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

	      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.

	      Contains	major  and  minor numbers of each partition as well as
	      number of blocks and partition name.

	      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 non-optionally 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.

	      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.

	      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.

	      [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, etc.

	      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.

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

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


	      See slabinfo(5) for details.

	      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 user mode, user mode  with  low  priority
		     (nice),  system  mode,  and  the idle task, respectively.
		     The last value should be USER_HZ times the  second  entry
		     in the uptime pseudo-file.

		     In Linux 2.6 this line includes three additional columns:
		     iowait - time waiting for I/O to complete (since 2.5.41);
		     irq  -  time  servicing  interrupts  (since 2.6.0-test4);
		     softirq - time servicing softirqs (since 2.6.0-test4).

		     Since Linux 2.6.11, there is an eighth  column,  steal  -
		     stolen  time,  which is the time spent in other operating
		     systems when running in a virtualized environment

		     Since Linux 2.6.24, there is a ninth column, guest, which
		     is the time spent running a virtual CPU for guest operat
		     ing 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

	      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

	      disk_io: (2,0):(31,30,5764,1,2) (3,0):...
		     (major,minor):(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 (January 1,	1970).

	      processes 86031
		     Number of forks since boot.

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

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

	      Swap areas in use.  See also swapon(8).

	      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
	      file system, and the sysctl(2) system  call.   Presently,  there
	      are  subdirectories  abi,  debug,  dev,  fs,  kernel, net, proc,
	      rxrpc, sunrpc and vm that each contain more files and  subdirec

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

	      This directory may be empty.

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

	      This  contains  the  subdirectories  binfmt_misc,  inotify,  and
	      mqueue,  and  files  dentry-state,  dir-notify-enable, dquot-nr,
	      file-max,  file-nr,  inode-max,  inode-nr,  inode-state,	lease-
	      break-time,     leases-enable,	 overflowgid,	  overflowuid,
	      suid_dumpable, super-max, and super-nr.

	      Documentation for files in this directory can be	found  in  the
	      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	 non-zero   when   the	 kernel   has	called
		shrink_dcache_pages() and the dcache isnt pruned yet.

	      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.

	      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

	      This  file  shows the number of allocated disk quota entries and
	      the number of free disk quota entries.

	      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 about running out of file handles, try increasing  this

	      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.

	      If you  increase	/proc/sys/fs/file-max,	be  sure  to  increase
	      /proc/sys/fs/inode-max   to   3-4   times   the	new  value  of
	      /proc/sys/fs/file-max, or you will run out of inodes.

	      This (read-only)	file  gives  the  number  of  files  presently
	      opened.  It contains three numbers: the number of allocated file
	      handles; the number of free file handles; and the maximum number
	      of file handles.	The kernel allocates file handles dynamically,
	      but it doesnt free them again.   If  the	number	of  allocated
	      files  is  close	to the maximum, you should consider increasing
	      the maximum.  When the number of free  file  handles  is	large,
	      youve  encountered a peak in your usage of file handles and you
	      probably dont need to increase the maximum.

	      This file contains the maximum number of in-memory  inodes.   On
	      some (2.4) systems, it may not be present.  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.

	      This file contains the first two values from inode-state.

	      This file contains  seven  numbers:  nr_inodes,  nr_free_inodes,
	      preshrink,  and  four  dummy values.  nr_inodes is the number of
	      inodes the system has allocated.	This can be slightly more than
	      inode-max  because Linux allocates them one page full at a time.
	      nr_free_inodes represents the number of free inodes.   preshrink
	      is  non-zero when the nr_inodes > inode-max and the system needs
	      to prune the inode list instead of allocating more.

       /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).

	      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.

	      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 non-zero 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  file	systems  only  support
	      16-bit  UIDs  and  GIDs,	although in Linux UIDs and GIDs are 32
	      bits.  When one of these file systems  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/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)
	      behavior.   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 file system user ID of the dumping process
	      and no security is applied.  This is intended for system	debug
	      ging 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 adminis
	      trators are attempting to debug problems in  a  normal  environ

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

	      This file contains the number of file systems currently mounted.

	      This directory contains files  controlling  a  range  of	kernel
	      parameters, a described below.

	      This  file contains three numbers: highwater, lowwater, and fre
	      quency.  If BSD-style process accounting is enabled these values
	      control  its  behavior.	If free space on file system 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-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).

	      See core(5).

	      See core(5).

	      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, Linuxs  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 its up to the program to decide what to do with it.

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

       /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.

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

	      (PowerPC only) This file contains a flag that  controls  the  L2
	      cache  of  G3  processor	boards.   If 0, the cache is disabled.
	      Enabled if non-zero.

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

	      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.

	      This file defines the system-wide limit on the number of message
	      queue  identifiers.   (This  file  is  only present in Linux 2.4

	      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/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

	      This  file  gives  read/write  access  to  the  kernel  variable
	      panic_timeout.   If  this  is  zero,  the  kernel will loop on a
	      panic; if non-zero 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 kernels 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  non-
	      zero 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.

	      The four values in this file are console_loglevel,  default_mes
	      sage_loglevel, minimum_console_level,
	       and  default_console_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

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

	      This file defines the maximum number of pseudo-terminals.

	      This read-only file indicates how many pseudo-terminals are cur
	      rently in use.

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

	      This  file  is  documented  in the kernel source file Documenta

       /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

	      (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.

	      (Only in kernels up to and including 2.6.7.)   This  file  shows
	      the number POSIX real-time signals currently queued.

       /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

	      This file shows the size of the generic SCSI device (sg) buffer.
	      You cant 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 shouldnt be any reason  to  change
	      this value.

	      This  file contains the system-wide limit on the total number of
	      pages of System V shared memory.

	      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.

	      (available  in  Linux  2.4  and onwards) This file specifies the
	      system-wide maximum number of System V  shared  memory  segments
	      that can be created.

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

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

	      This  file  defines  a ceiling value for the backlog argument of
	      listen(2); see the listen(2) manual page for details.

	      This directory may be empty.

	      This directory supports Sun remote procedure  call  for  network
	      file system (NFS).  On some systems, it is not present.

	      This  directory  contains  files	for  memory management tuning,
	      buffer 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

	      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   >

	      Because  this  is  a non-destructive 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 non-zero, this disables the new 32-bit memory-mapping layout;
	      the kernel will use the legacy (2.4) layout for all processes.

       /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, pro
	      cess): 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/[number]/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 non-zero, 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 non-zero, 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 non-zero,  it  takes  precedence
	      over  whatever  value  is used in /proc/sys/vm/oom_kill_allocat

	      The default value is 0.

	      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 non-zero 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.

	      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

	      If this file is set to the value 0, the kernels 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.

	      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.

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

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

	      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
	    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.

       Many strings (i.e., the environment and command line) are in the inter
       nal format, with sub-fields 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 ` works well.

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

       cat(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),
       dmesg(8),   hdparm(8),	ifconfig(8),   init(8),   lsmod(8),  lspci(8),
       mount(8), netstat(8), procinfo(8), route(8)
       The kernel source files: Documentation/filesystems/proc.txt, Documenta

       This  page  is  part of release 3.05 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				  2008-07-15			       PROC(5)

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