Ubuntu Manpages

/proc/pid/personality

execution domain

/proc/pid/personality (since Linux 2.6.28)
This read-only file exposes the process's execution domain, as set by personality(2). The value is displayed in hexadecimal notation.
Permission to access this file is governed by a ptrace access mode PTRACE_MODE_ATTACH_FSCREDS check; see ptrace(2).

proc(5)