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)