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NAME | DESCRIPTION | SEE ALSO | COLOPHON |
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proc_pid(5) File Formats Manual proc_pid(5)
/proc/pid/, /proc/self/ - process information
/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. However, as a security measure, the ownership is
made root:root if the process's "dumpable" attribute is set
to a value other than 1.
Before Linux 4.11, root:root meant the "global" root user
ID and group ID (i.e., UID 0 and GID 0 in the initial user
namespace). Since Linux 4.11, if the process is in a
noninitial user namespace that has a valid mapping for user
(group) ID 0 inside the namespace, then the user (group)
ownership of the files under /proc/pid is instead made the
same as the root user (group) ID of the namespace. This
means that inside a container, things work as expected for
the container "root" user.
The process's "dumpable" attribute may change for the
following reasons:
• The attribute was explicitly set via the prctl(2)
PR_SET_DUMPABLE operation.
• The attribute was reset to the value in the file
/proc/sys/fs/suid_dumpable (described below), for the
reasons described in prctl(2).
Resetting the "dumpable" attribute to 1 reverts the
ownership of the /proc/pid/* files to the process's
effective UID and GID. Note, however, that if the
effective UID or GID is subsequently modified, then the
"dumpable" attribute may be reset, as described in
prctl(2). Therefore, it may be desirable to reset the
"dumpable" attribute after making any desired changes to
the process's effective UID or GID.
/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(5)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
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⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
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man-pages@man7.org
Linux man-pages 6.15 2025-05-17 proc_pid(5)
Pages that refer to this page: PR_SET_DUMPABLE(2const)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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