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NAME

       proc - process information pseudo-file system

DESCRIPTION

       The  proc file system is a pseudo-file system which is used as 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 outline gives a quick tour through 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]/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 characters.  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:

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

       /proc/[pid]/exe
              Under Linux 2.2 and later, this file is  a  symbolic  link  containing  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 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/[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, etc.

              In a multithreaded process, the contents of this directory are not available if the
              main thread has already terminated (typically 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 argument, 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, 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 symbolically 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 contents 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 offset.  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]/limits (since kernel 2.6.24)
              This file displays the soft limit, hard limit, and units of measurement for each of
              the  process's  resource  limits (see getrlimit(2)).  The file is protected to only
              allow reading by the real UID of the process.

       /proc/[pid]/maps
              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.

       /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 file system (see stat(2)).

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

              (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)  file system type: name of file system in the form "type[.subtype]".

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

              (11) super options: per-super block options.

              Parsers should ignore all unrecognized optional  fields.   Currently  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 "master:X" field is  present  and  not  the  "propagate_from:X"
              field.

              For        more       information       on       mount       propagation       see:
              Documentation/filesystems/sharedsubtree.txt in the kernel source tree.

       /proc/[pid]/mounts (since Linux 2.4.19)
              This is a list of all the file systems currently mounted  in  the  process's  mount
              namespace.   The  format  of  this  file  is  documented 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 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.

       /proc/[pid]/mountstats (since Linux 2.6.17)
              This  file  exports  information  (statistics, configuration information) 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 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/[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 terminate.

              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 namespace  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 terminate.

              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.

       /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  bit-shift  adjustment  specified  by  the  oom_adj
              setting for the process.

       /proc/[pid]/root
              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
              process's 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/[pid]/smaps (since Linux 2.6.14)
              This file shows memory consumption for each of the process's 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 displayed 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, the number of clean and dirty
              shared pages in the mapping, and the number of clean and dirty private pages in the
              mapping.

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

       /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 specifiers, 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  zombie,  T  is traced or stopped (on a signal), and W is
                          paging.

              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 to 8.)

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

              flags %u (%lu before Linux 2.6.22)
                          The  kernel  flags word of the process.  For bit meanings, see the PF_*
                          defines in <linux/sched.h>.  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 disk.

              cminflt %lu The  number of minor faults that the process's 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 process's 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 sysconf(_SC_CLK_TCK).

              cutime %ld  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  Amount of time  that  this  process's  waited-for  children  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 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    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 kernel 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 boot.

              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 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  Current soft limit in  bytes  on  the  rss  of  the  process;  see  the
                          description of RLIMIT_RSS in getpriority(2).

              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 stack.

              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  decimal   number.
                          Obsolete, because it does not provide information on real-time signals;
                          use /proc/[pid]/status instead.

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

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

              wchan %lu   This is the "channel" in which the  process  is  waiting.   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 maintained).

              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 sched_setscheduler(2)).

              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 (centiseconds).

              guest_time %lu (since Linux 2.6.24)
                          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)
                          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       total program size
                             (same as VmSize in /proc/[pid]/status)
                  resident   resident set size
                             (same as VmRSS in /proc/[pid]/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)

       /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 file system 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 capabilities(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] directories.  For attributes  that
              are  shared by all threads, the contents 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  terminated  (typically  by  calling
              pthread_exit(3)).

       /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/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 configuring 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   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.

       /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 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 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 didn't manage  to  determine  the  file  system  type.   Then  file  systems
              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  architectures,  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 different 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 messages.

              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 separated
              by a slash (/).  The first of these is the number  of  currently  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 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 only present 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 memory (both physical and swap) on
              the system as well as the shared memory and buffers used by the kernel.

       /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  file  systems  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 documented
              in fstab(5).

       /proc/mtrr
              Memory Type Range Registers.  See the 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  structures  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  kernel  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  kernel  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  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 hold internal information of the kernel socket state and are only useful for
              debugging.  The "uid" field holds the effective UID of the creator 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  kernel  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 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 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
              datagram  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 major and minor numbers of each partition as well as number of blocks  and
              partition name.

       /proc/pci
              This  is  a listing of all PCI devices found during kernel initialization 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
              CONFIG_PCI_LEGACY_PROC set), and finally removed altogether since Linux 2.6.17.

       /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 subsystem 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 currently 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  registered  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 configuration, 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.

       /proc/self
              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.

       /proc/slabinfo
              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:

                  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 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 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 file system, and the (deprecated) sysctl(2) system call.

       /proc/sys/abi (since Linux 2.4.10)
              This directory may contain files with  application  binary  information.   See  the
              kernel source file Documentation/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 file systems.

       /proc/sys/fs/binfmt_misc
              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 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 about running out of file handles, try increasing 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.

              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.

       /proc/sys/fs/file-nr
              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 doesn't 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, you've encountered a peak in your usage of file
              handles and you probably don't need to increase the maximum.

       /proc/sys/fs/inode-max
              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.

       /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.  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  nonzero
              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 interface.  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 signal to that process notifying it that
              another process is waiting to open the file.  If the lease holder does  not  remove
              or  downgrade  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 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/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/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 binaries.  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 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.

       /proc/sys/fs/super-max
              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.

       /proc/sys/fs/super-nr
              This file contains the number of file systems 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 frequency.  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 capability
              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 keyboard.  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, without 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/hotplug
              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 hostname "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/htab-reclaim
              (PowerPC only) If this file is set to a nonzero value, the PowerPC htab (see kernel
              file Documentation/powerpc/ppc_htab.txt) is pruned each time the  system  hits  the
              idle loop.

       /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  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).

       /proc/sys/kernel/msgmax
              This  file  defines a system-wide limit specifying the maximum number of bytes in a
              single message written on a System V message queue.

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

       /proc/sys/kernel/msgmnb
              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
              /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 autoreboot 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_message_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 console_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 currently in use.

       /proc/sys/kernel/random
              This directory contains various parameters controlling the operation  of  the  file
              /dev/random.  See random(4) for further information.

       /proc/sys/kernel/real-root-dev
              This file is documented in the kernel source file Documentation/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/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/shmall
              This  file  contains the system-wide limit on the total number of pages of System V
              shared memory.

       /proc/sys/kernel/shmmax
              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
              (available in Linux 2.4 and onward) 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
              specifically 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 - bitmask 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 signalling of processes (term, kill, oom-kill)
                      128 - allow reboot/poweroff
                      256 - allow nicing of all real-time tasks

              This  file is only present if the CONFIG_MAGIC_SYSRQ kernel configuration option is
              enabled.  For further details see the 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 file system (NFS).
              On some systems, it is not present.

       /proc/sys/vm
              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 free.

              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 this 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 handled 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 affecting any
              applications.  But if there is no other up-to-date copy of the data, it  will  kill
              processes to prevent any data corruptions from propagating.

              The file has one of the following values:

              1:  Kill  all  processes  that have the corrupted-and-not-reloadable 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 only kill  a  process  who
                  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 only active 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_MEMORY_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_MEMORY_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 possibly 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_allocating_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 getting 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 situation.

              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 function as typing ALT-
              SysRq-<character> (see the description of /proc/sys/kernel/sysrq).   This  file  is
              normally  only  writable  by  root.  For further details see the kernel source file
              Documentation/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 (seconds), and the  amount
              of time spent in idle process (seconds).

       /proc/version
              This  string  identifies the kernel version that is currently running.  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 useful for analyzing
              virtual memory behavior.

NOTES

       Many strings (i.e., the environment and command line) are in  the  internal  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), netstat(8), procinfo(8), route(8)
       The kernel source files: Documentation/filesystems/proc.txt, Documentation/sysctl/vm.txt

COLOPHON

       This page is part of release 3.35 of the Linux man-pages project.  A  description  of  the
       project,  and information about reporting bugs, can be found at http://man7.org/linux/man-
       pages/.