proc
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## Name

proc — process and system information pseudo-filesystem

## Description

The `proc` filesystem is a pseudo-filesystem which provides an interface to Cygwin data structures. It is commonly mounted at `/proc`. Typically, it is mounted automatically by the system.

### Overview

Underneath `/proc`, there are the following general groups of files and subdirectories:

`/proc/[pid]` subdirectories

  Each one of these subdirectories contains files and subdirectories exposing information about the process with the corresponding process id.

  The `/proc/[pid]` subdirectories are visible when iterating through `/proc` with readdir(2) (and thus are visible when one uses ls(1) to view the contents of `/proc`).

`/proc/self`

  When a process accesses this magic symbolic link, it resolves to the process's own `/proc/[pid]` directory.

`/proc/[a-z]*`

  Various other files and subdirectories under `/proc` expose system-wide information.

All of the above are described in more detail below.

### Files and directories

The following list provides details of many of the files and directories under the `/proc` hierarchy.

`/proc/[pid]`

  There is a numerical subdirectory for each running process; the subdirectory is named by the process id. Each `/proc/[pid]` subdirectory contains the pseudo-files and directories described below.

  The files inside each `/proc/[pid]` directory are normally owned by the effective user and effective group id of the process.

`/proc/[pid]/cmdline`

  This read-only file 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 followed by null bytes ('\0').

`/proc/[pid]/ctty`

  This read-only file holds the name of the console or control terminal device for the process, unless the process is detached from any terminal. In the latter case, there is only a newline in this file.

`/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`.

`/proc/[pid]/environ`

  This read-only file contains the current environment that may have been changed by the currently executing program. 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 -A /proc/1/environ

  If, after an execve(2), the process modifies its environment (e.g., by calling functions such as putenv(3) or modifying the environ(7) variable directly), this file will reflect those changes. That may not be the case on other systems such as Linux.

`/proc/[pid]/exe`

  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 that is being run by process [pid]. `/proc/[pid]/exe` is a pointer to the binary which was executed, and appears as a symbolic link.

`/proc/[pid]/exename`

  This read-only file contains the actual pathname of the executed command.

`/proc/[pid]/fd/`

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

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

  For example, `socket:[2248868]` will be a socket and its inode is 2248868.

  Programs that take a filename as a command-line argument, but don't take input from standard input if no argument is supplied, and programs that write to a file named as a command-line argument, but don't send their output to standard output if no argument is supplied, can nevertheless be made to use standard input or standard output by using `/proc/[pid]/fd` files as command-line arguments. 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 ...

  Note that for file descriptors referring to inodes (pipes and sockets, see above), those inodes still have permission bits and ownership information distinct from those of the `/proc/[pid]/fd` entry, and that the owner may differ from the user and group ids of the process. An unprivileged process may lack permissions to open them, as in this example:

      		  $ echo test | sudo -u nobody cat
      		  test
      		  $ echo test | sudo -u nobody cat /proc/self/fd/0
      		  cat: /proc/self/fd/0: Permission denied

  File descriptor 0 refers to the pipe created by the shell and owned by that shell's user, which is not `nobody`, so cat does not have permission to create a new file descriptor to read from that inode, even though it can still read from its existing file descriptor 0.

`/proc/[pid]/gid`

  This read-only file contains the primary group id for the process.

`/proc/[pid]/maps`

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

  The format of the file is:

      address          perms offset   dev       inode               pathname

      00010000-00020000 rw-s 00000000 0000:0000 0                   [win heap 1 default shared]
      ...
      00080000-00082000 rw-p 00000000 0000:0000 0                   [win heap 0 default grow]
      00082000-0009A000 ===p 00002000 0000:0000 0                   [win heap 0 default grow]
      000A0000-000A1000 rw-p 00000000 0000:0000 0                   [win heap 2 grow]
      000A1000-000BA000 ===p 00001000 0000:0000 0                   [win heap 2 grow]
      000C0000-000D9000 rw-p 00000000 0000:0000 0                   [win heap 0 default grow]
      000D9000-001C0000 ===p 00019000 0000:0000 0                   [win heap 0 default grow]
      00200000-00377000 ===p 00000000 0000:0000 0
      00377000-00378000 rw-p 00177000 0000:0000 0                   [peb]
      00378000-0037A000 rw-p 00178000 0000:0000 0                   [teb (tid 8844)]
      ...
      00400000-005F9000 ===p 00000000 0000:0000 0                   [stack (tid 8884)]
      005F9000-005FC000 rw-g 001F9000 0000:0000 0                   [stack (tid 8884)]
      005FC000-00600000 rw-p 001FC000 0000:0000 0                   [stack (tid 8884)]
      00600000-006C7000 r--s 00000000 EE45:4341 281474976741117     /proc/cygdrive/c/Windows/System32/locale.nls
      ...
      100400000-100401000 r--p 00000000 EE45:4341 281474978095037   /usr/bin/sh.exe
      100401000-100413000 r-xp 00001000 EE45:4341 281474978095037   /usr/bin/sh.exe
      100413000-100414000 rw-p 00013000 EE45:4341 281474978095037   /usr/bin/sh.exe
      ...
      180010000-180020000 rw-s 00000000 0000:0000 0                 [procinfo]
      180020000-180029000 rw-s 00000000 0000:0000 0                 [cygwin-user-shared]
      180030000-18003C000 rw-s 00000000 0000:0000 0                 [cygwin-shared]
      180040000-180041000 r--p 00000000 EE45:4341 2251799814294868   /usr/bin/cygwin1.dll
      180041000-18022D000 r-xp 00001000 EE45:4341 2251799814294868   /usr/bin/cygwin1.dll
      18022D000-180231000 rwxp 001ED000 EE45:4341 2251799814294868   /usr/bin/cygwin1.dll
      180231000-18026A000 rw-p 001F1000 EE45:4341 2251799814294868   /usr/bin/cygwin1.dll
      ...
      800000000-800090000 rw-p 00000000 0000:0000 0                 [heap]
      800090000-820000000 ===p 00090000 0000:0000 0                 [heap]
      7FF4FDEB0000-7FF4FDEB5000 r--s 00000000 0000:0000 0
      7FF4FDEB5000-7FF4FDFB0000 ===s 00005000 0000:0000 0
      7FF4FDFB0000-7FF5FDFD0000 ===p 00000000 0000:0000 0
      ...
      7FFBEEAC0000-7FFBEEAC1000 r--p 00000000 EE45:4341 844424934724994   /proc/cygdrive/c/Windows/System32/kernel32.dll
      7FFBEEAC1000-7FFBEEB36000 r-xp 00001000 EE45:4341 844424934724994   /proc/cygdrive/c/Windows/System32/kernel32.dll
      7FFBEEB36000-7FFBEEB68000 r--p 00076000 EE45:4341 844424934724994   /proc/cygdrive/c/Windows/System32/kernel32.dll
      7FFBEEB68000-7FFBEEB6A000 rw-p 000A8000 EE45:4341 844424934724994   /proc/cygdrive/c/Windows/System32/kernel32.dll
      7FFBEEB6A000-7FFBEEB72000 r--p 000AA000 EE45:4341 844424934724994   /proc/cygdrive/c/Windows/System32/kernel32.dll
      ...

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

  r

    read

  w

    write

  x

    execute

  ===

    reserved

  s

    shared

  g

    guard

  p

    private

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

  The `pathname` field will usually be the file that is backing the mapping.

  There are additional helpful pseudo-paths:

  [`cygwin-shared`]

    Global shared Cygwin process information.

  [`cygwin-user-shared`]

    Global shared Cygwin user information.

  [`peb`]

    Windows Process Environment Block.

  [`procinfo`]

    Cygwin process information.

  [`shared-user-data`]

    Shared user information.

  [`heap`]

    The process's heap.

  [`stack`]

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

  [`stack` (tid `<tid>`)]

    A thread's stack (where the `<tid>` is a thread id).

  [`teb` (tid `<tid>`)]

    Windows Thread Environment Block (where `<tid>` is a thread id).

  [`win heap <n> default shared exec grow noserial debug`]

    Windows extended heap (where `<n>` is a heap id) and the rest of the words are heap flags:

    `default`

      default heap flags

    `shared`

      shareable and mapped heap flags

    `exec`

      executable heap flag

    `grow`

      growable heap flag

    `noserial`

      do not serialize heap flag

    `debug`

      debugged heap flag

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

  `pathname` is shown unescaped except for newline characters, which are replaced with an octal escape sequence. As a result, it is not possible to determine whether the original `pathname` contained a newline character or the literal `\e012` character sequence.

  If the mapping is file-backed and the file has been deleted, the string "`(deleted)`" is appended to the `pathname`. Note that this is ambiguous too.

`/proc/[pid]/mountinfo`

  This file contains information about mount points in the process's mount namespace (see mount_namespaces(7)). It supplies various information (e.g., propagation state, root of mount for bind mounts, identifier for each mount and its parent) that is missing from the (older) `/proc/[pid]/mounts` file, and fixes various other problems with that file (e.g., nonextensibility, failure to distinguish per-mount versus per-superblock options).

  The file 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)

  The numbers in parentheses are labels for the descriptions below:

  (1)

    mount id: a unique id for the mount (may be reused after umount(2)).

  (2)

    parent id: the id of the parent mount (or of self for the root of this mount namespace's mount tree).

  (3)

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

  (4)

    root: the pathname of the directory in the filesystem which forms the root of this mount.

  (5)

    mount point: the pathname of the mount point relative to the process's root directory.

  (6)

    mount options: per-mount options (see mount(2)).

  (?)

    optional fields: zero or more fields of the form "tag`[:`value`]`"; see below.

  (7)

    separator: the end of the optional fields is marked by a single hyphen.

  (8)

    filesystem type: the filesystem type in the form "type`[.`subtype`]`".

  (9)

    mount source: filesystem-specific information or "`none`".

  (10)

    super options: per-superblock options (see mount(2)).

`/proc/[pid]/mounts`

  This file lists all the filesystems currently mounted in the process's mount namespace (see mount_namespaces(7)). The format of this file is documented in fstab(5).

`/proc/[pid]/pgid`

  This read-only file contains the process group id for the process.

`/proc/[pid]/ppid`

  This read-only file contains the parent process id for the process.

`/proc/[pid]/root`

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

`/proc/[pid]/sid`

  This read-only file contains the session id for the process.

`/proc/[pid]/stat`

  Status information about the process. This is used by some implementations of ps(1).

  The fields, in order, with their proper scanf(3) format specifiers, are listed below.

  (1) pid %d

    The process id.

  (2) comm %s

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

  (3) state %c

    One of the following characters, indicating process state:

    R

      Runnable

    O

      Running

    S

      Sleeping in an interruptible wait

    D

      Waiting in uninterruptible disk sleep

    Z

      Zombie

    T

      Stopped (on a signal) or trace stopped

  (4) ppid %d

    The PID of the parent of this process.

  (5) pgrp %d

    The process group id of the process.

  (6) session %d

    The session id of the process.

  (7) 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.)

  (8) tpgid %d

    The id of the foreground process group of the controlling terminal of the process.

  (9) flags %u

    The kernel flags word of the process.

  (10) minflt %lu

    The number of minor faults the process has made which have not required loading a memory page from disk.

  (11) cminflt %lu

    The number of minor faults that the process's waited-for children have made.

  (12) majflt %lu

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

  (13) cmajflt %lu

    The number of major faults that the process's waited-for children have made.

  (14) utime %lu

    Amount of time that this process has been scheduled in user mode, measured in clock ticks (divide by `sysconf(_SC_CLK_TCK)`).

  (15) stime %lu

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

  (16) 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)).

  (17) 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)`).

  (18) priority %ld

    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.

  (19) nice %ld

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

  (20) num_threads %ld

    Number of threads in this process. Currently shown as 0.

  (21) itrealvalue %ld

    The time in jiffies before the next `SIGALRM` is sent to the process due to an interval timer. This field is no longer maintained, and is hard coded as 0.

  (22) starttime %llu

    The time the process started after system boot. The value is expressed in clock ticks (divide by `sysconf(_SC_CLK_TCK)`).

  (23) vsize %lu

    Virtual memory size in bytes.

  (24) 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.

  (25) rsslim %lu

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

`/proc/[pid]/statm`

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

  (1) size

    total program size (same as VmSize in `/proc/[pid]/status`)

  (2) resident

    resident set size (same as VmRSS in `/proc/[pid]/status`)

  (3) shared

    number of resident shared pages (i.e., backed by a file) (same as RssFile+RssShmem in `/proc/[pid]/status`)

  (4) text

    text (code)

  (5) lib

    library

  (6) data

    data + stack

  (7) dt

    dirty pages (always 0)

`/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
      		  Umask:  0022
      		  State:  S (sleeping)
      		  Tgid:   17248
      		  Pid:    17248
      		  PPid:   17200
      		  Uid:    1000    1000    1000    1000
      		  Gid:    100     100     100     100
      		  VmSize:	  131168 kB
      		  VmLck:	       0 kB
      		  VmRSS:	   13484 kB
      		  VmData:	   10332 kB
      		  VmStk:	     136 kB
      		  VmExe:	     992 kB
      		  VmLib:	    2104 kB
      		  SigPnd: 0000000000000000
      		  SigBlk: 0000000000010000
      		  SigIgn: 0000000000384004

  The fields are as follows:

  - Name: Command run by this process.

  - Umask: Process umask, expressed in octal with a leading zero; see umask(2).

  - State: Current state of the process. One of:

    R

      runnable

    O

      running

    S

      sleeping

    D

      disk sleep

    T

      stopped or tracing stop

    Z

      zombie

  - Tgid: Thread group id (i.e., Process id).

  - Pid: Thread id (see gettid(2)).

  - PPid: PID of parent process.

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

  - VmSize: Virtual memory size.

  - VmLck: Locked memory size (see mlock(2)).

  - VmRSS: Resident set size.

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

  - VmLib: Shared library code size.

  - SigPnd: Number of signals pending for process as a whole (see pthreads(7) and signal(7)).

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

`/proc/[pid]/uid`

  This read-only file contains the user id for the process.

`/proc/[pid]/winexename`

  This read-only file contains the Windows pathname of the executed command.

`/proc/[pid]/winpid`

  This read-only file contains the Windows process id for the process.

`/proc/cpuinfo`

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

`/proc/cygdrive`

  This file is a symbolic link that points to the user's Windows mapped drive mount point, similar to root.

`/proc/devices`

  Text listing of major numbers and device groups. This can be used by makedev scripts for consistency with the system.

`/proc/filesystems`

  A text listing of the filesystems which are supported by Cygwin. (See also filesystems(5).) If a filesystem is marked with "nodev", this means that it does not require a block device to be mounted (e.g., virtual filesystem, network filesystem).

`/proc/loadavg`

  The first three fields in this file are load average figures giving the number of jobs in the run queue (state R) 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 runnable scheduling entities (processes, threads). The value after the slash is the number of scheduling entities that currently exist on the system.

`/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 system. Each line of the file consists of a parameter name, followed by a colon, the value of the parameter, and an option unit of measurement (e.g., "kB"). The list below describes the parameter names and the format specifier required to read the field value. Some fields are displayed only if the system was configured with various options; those dependencies are noted in the list.

  MemTotal %lu

    Total usable RAM (i.e., physical RAM minus a few reserved bits and the system binary code).

  MemFree %lu

    The sum of LowFree + HighFree.

  HighTotal %lu

    Total amount of highmem.

  HighFree %lu

    Amount of free highmem.

  LowTotal %lu

    Total amount of lowmem. Lowmem is memory which can be used for everything that highmem can be used for, but it is also available for the system's use for its own data structures. Bad things happen when you're out of lowmem.

  LowFree %lu

    Amount of free lowmem.

  SwapTotal %lu

    Total amount of swap space available.

  SwapFree %lu

    Amount of swap space that is currently unused.

`/proc/misc`

  Text listing of minor device numbers and names of devices with major device number of the `misc` device group. This can be used by makedev scripts for consistency with the system.

`/proc/mounts`

  With the introduction of per-process mount namespaces, 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/net`

  This directory contains various files and subdirectories containing information about the networking layer. The 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/if_inet6`

  This file contains information about IP V6 interface adapters, if used. Each line represents an IP V6 interface adapter.

      fe800000000000002c393d3da6108636 12 40 20 80 {C6B5FBE5-A3AC-4DB0-A308-8EE94E1406A4}
      fe8000000000000039da016f76bd92bc 13 40 20 20 {E06B8972-0918-41FC-851B-090C446C7D1C}
      fe8000000000000050ba9cedf1fe1628 0b 40 20 20 {680ED6FD-DFAC-4398-AA85-FB33E17E38EA}
      fe8000000000000030c5c6a0b30f109d 11 40 20 20 {B9E39F53-1659-4065-BDA5-F41162250E03}
      20021840ac2c12343427e3b9ec6fa585 08 40 00 80 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      20021840ac2c12342403e3b2c7a5a32f 08 80 00 20 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      20021840ac2c1234284e8d0ecb4160cb 08 80 00 20 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      20021840ac2c123468cb06ea72f1d678 08 80 00 80 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      20021840ac2c12346cb59aca97c36e3b 08 80 00 20 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      20021840ac2c123498af9881de1fb828 08 80 00 20 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      20021840ac2c1234cd62a3d73a498611 08 80 00 20 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      20021840ac2c1234e410c873be09df93 08 80 00 20 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      fe800000000000003427e3b9ec6fa585 08 40 20 80 {4083A7F8-99CF-4220-8715-6FDF268B002F}
      00000000000000000000000000000001 01 80 10 80 {2B5345AC-7502-11EA-AC73-806E6F6E6963}
      			   (1)  (2)(3)(4)(5)  (6)

  The fields in each line are:

  (1)

    The IP V6 address of the interface adapter.

  (2)

    The IP V6 interface adapter index.

  (3)

    The prefix length of the IP V6 interface address.

  (4)

    The scope of the IP V6 interface address.

  (5)

    The state of the IP V6 interface address.

  (6)

    The DUID/GUID/UUID of the IP V6 interface adapter.

  The last number exists only for compatibility reasons and is always 1.

`/proc/partitions`

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

`/proc/registry`

  Under Cygwin, this directory contains subdirectories for registry paths, keys, and subkeys, and files named for registry values which contain registry data, for the current process.

`/proc/registry32`

  Under 64 bit Windows, this directory contains subdirectories for registry paths, keys, and subkeys, and files named for registry values which contain registry data, for 32 bit processes.

`/proc/registry64`

  Under 64 bit Windows, this directory contains subdirectories for registry paths, keys, and subkeys, and files named for registry values which contain registry data, for 64 bit processes.

`/proc/self`

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

`/proc/stat`

  system statistics. Varies with architecture. Common entries include:

  cpu 10132153 0 3084719 46828483
  cpu0 1393280 0 572056 13343292

    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 ("cpu" line) or the specific CPU ("cpu N" line) spent in various states:

    (1) user

      Time spent in user mode.

    (2) nice

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

    (3) system

      Time spent in system mode.

    (4) idle

      Time spent in the idle task.

  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

    The number of interrupts serviced.

  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).

`/proc/swaps`

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

`/proc/sys`

  This directory contains a number of files and subdirectories linking to Windows objects, which can be read using these entries.

  String values may be terminated by either '\0' or '\n'.

  Integer and long values may be either in decimal or in hexadecimal notation (e.g. 0x3FFF). Multiple integer or long values may be separated by any of the following whitespace characters: ' ', '\t', or '\n'.

`/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 are only available if the cygserver Cygwin service is running. 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/uptime`

  This file contains two numbers (values in seconds): the uptime of the system (including time spent in suspend) and the amount of time spent in the idle process.

`/proc/version`

  This string identifies the Cygwin version that is currently running. For example:

      CYGWIN_NT-10.0-18363 version 3.1.7-340.x86_64 (corinna@calimero) (gcc version 9.3.0 20200312 (Fedora Cygwin 9.3.0-1) (GCC) ) 2020-08-22 17:48 UTC

## Notes

Many files contain strings (e.g., the environment and command line) that are in the internal format, with subfields terminated by null bytes ('\0'). When inspecting such files, you may find that the results are more readable if you use a command of the following form to display them:

    	  $ cat -A file

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

## See Also

cat(1), find(1), free(1), ps(1), pstree(1), tr(1), uptime(1), chroot(2), mmap(2), readlink(2), syslog(2), hier(7), arp(8), mount(8), netstat(8), route(8).

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