NAME

       /proc/pid/, /proc/self/ - process information

DESCRIPTION

       /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.

SEE ALSO

       proc(5)