1PROC(5)                    Linux Programmer's Manual                   PROC(5)
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NAME

6       proc - process information pseudo-file system
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DESCRIPTION

9       The proc file system is a pseudo-file system which is used as an inter‐
10       face to kernel data structures.  It is commonly mounted at /proc.  Most
11       of  it  is  read-only,  but  some  files  allow  kernel variables to be
12       changed.
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14       The following outline gives a quick tour through the /proc hierarchy.
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16       /proc/[pid]
17              There is a numerical subdirectory for each running process;  the
18              subdirectory is named by the process ID.  Each such subdirectory
19              contains the following pseudo-files and directories.
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21       /proc/[pid]/auxv (since 2.6.0-test7)
22              This contains the contents of the  ELF  interpreter  information
23              passed  to the process at exec time.  The format is one unsigned
24              long ID plus one unsigned long value for each entry.   The  last
25              entry contains two zeros.
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27       /proc/[pid]/cgroup (since Linux 2.6.24)
28              This  file  describes  control  groups to which the process/task
29              belongs.  For each cgroup hierarchy there is one entry  contain‐
30              ing colon-separated fields of the form:
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32                  5:cpuacct,cpu,cpuset:/daemons
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34              The colon-separated fields are, from left to right:
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36                  1. hierarchy ID number
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38                  2. set of subsystems bound to the hierarchy
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40                  3. control  group  in  the  hierarchy  to  which the process
41                     belongs
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43              This file is present only if the CONFIG_CGROUPS kernel  configu‐
44              ration option is enabled.
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46       /proc/[pid]/cmdline
47              This holds the complete command line for the process, unless the
48              process is a zombie.  In the latter case, there  is  nothing  in
49              this  file:  that  is, a read on this file will return 0 charac‐
50              ters.  The command-line arguments appear in this file as  a  set
51              of  strings  separated by null bytes ('\0'), with a further null
52              byte after the last string.
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54       /proc/[pid]/coredump_filter (since kernel 2.6.23)
55              See core(5).
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57       /proc/[pid]/cpuset (since kernel 2.6.12)
58              See cpuset(7).
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60       /proc/[pid]/cwd
61              This is a symbolic link to the current working directory of  the
62              process.   To  find out the current working directory of process
63              20, for instance, you can do this:
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65                  $ cd /proc/20/cwd; /bin/pwd
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67              Note that the pwd command is often a shell built-in,  and  might
68              not work properly.  In bash(1), you may use pwd -P.
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70              In  a  multithreaded process, the contents of this symbolic link
71              are not available if the  main  thread  has  already  terminated
72              (typically by calling pthread_exit(3)).
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