/proc/[pid]/status

http://man7.org/linux/man-pages/man5/proc.5.html

/proc/[pid]/status
              Provides much of the information in /proc/[pid]/stat and
              /proc/[pid]/statm in a format that's easier for humans to
              parse.  Here's an example:

                  $ cat /proc/$$/status
                  Name:   bash
                  Umask:  0022
                  State:  S (sleeping)
                  Tgid:   17248
                  Ngid:   0
                  Pid:    17248
                  PPid:   17200
                  TracerPid:      0
                  Uid:    1000    1000    1000    1000
                  Gid:    100     100     100     100
                  FDSize: 256
                  Groups: 16 33 100
                  NStgid: 17248
                  NSpid:  17248
                  NSpgid: 17248
                  NSsid:  17200
                  VmPeak:     131168 kB
                  VmSize:     131168 kB
                  VmLck:           0 kB
                  VmPin:           0 kB
                  VmHWM:       13484 kB
                  VmRSS:       13484 kB
                  RssAnon:     10264 kB
                  RssFile:      3220 kB
                  RssShmem:        0 kB
                  VmData:      10332 kB
                  VmStk:         136 kB
                  VmExe:         992 kB
                  VmLib:        2104 kB
                  VmPTE:          76 kB
                  VmPMD:          12 kB
                  VmSwap:          0 kB
                  HugetlbPages:          0 kB        # 4.4
                  Threads:        1
                  SigQ:   0/3067
                  SigPnd: 0000000000000000
                  ShdPnd: 0000000000000000
                  SigBlk: 0000000000010000
                  SigIgn: 0000000000384004
                  SigCgt: 000000004b813efb
                  CapInh: 0000000000000000
                  CapPrm: 0000000000000000
                  CapEff: 0000000000000000
                  CapBnd: ffffffffffffffff
                  CapAmb:   0000000000000000
                  NoNewPrivs:     0
                  Seccomp:        0
                  Cpus_allowed:   00000001
                  Cpus_allowed_list:      0
                  Mems_allowed:   1
                  Mems_allowed_list:      0
                  voluntary_ctxt_switches:        150
                  nonvoluntary_ctxt_switches:     545

              The fields are as follows:

              * Name: Command run by this process.

              * Umask: Process umask, expressed in octal with a leading
                zero; see umask(2).  (Since Linux 4.7.)

              * State: Current state of the process.  One of "R (running)",
                "S (sleeping)", "D (disk sleep)", "T (stopped)", "T (tracing
                stop)", "Z (zombie)", or "X (dead)".

              * Tgid: Thread group ID (i.e., Process ID).

              * Ngid: NUMA group ID (0 if none; since Linux 3.13).

              * Pid: Thread ID (see gettid(2)).

              * PPid: PID of parent process.

              * TracerPid: PID of process tracing this process (0 if not
                being traced).

              * Uid, Gid: Real, effective, saved set, and filesystem UIDs
                (GIDs).

              * FDSize: Number of file descriptor slots currently allocated.

              * Groups: Supplementary group list.

              * NStgid : Thread group ID (i.e., PID) in each of the PID
                namespaces of which [pid] is a member.  The leftmost entry
                shows the value with respect to the PID namespace of the
                reading process, followed by the value in successively
                nested inner namespaces.  (Since Linux 4.1.)

              * NSpid: Thread ID in each of the PID namespaces of which
                [pid] is a member.  The fields are ordered as for NStgid.
                (Since Linux 4.1.)

              * NSpgid: Process group ID in each of the PID namespaces of
                which [pid] is a member.  The fields are ordered as for NSt‐
                gid.  (Since Linux 4.1.)

              * NSsid: descendant namespace session ID hierarchy Session ID
                in each of the PID namespaces of which [pid] is a member.
                The fields are ordered as for NStgid.  (Since Linux 4.1.)

              * VmPeak: Peak virtual memory size.

              * VmSize: Virtual memory size.

              * VmLck: Locked memory size (see mlock(3)).

              * VmPin: Pinned memory size (since Linux 3.2).  These are
                pages that can't be moved because something needs to
                directly access physical memory.

              * VmHWM: Peak resident set size ("high water mark").

              * VmRSS: Resident set size.  Note that the value here is the
                sum of RssAnon, RssFile, and RssShmem.

              * RssAnon: Size of resident anonymous memory.  (since Linux
                4.5).

              * RssFile: Size of resident file mappings.  (since Linux 4.5).

              * RssShmem: Size of resident shared memory (includes System V
                shared memory, mappings from tmpfs(5), and shared anonymous
                mappings).  (since Linux 4.5).

              * VmData, VmStk, VmExe: Size of data, stack, and text seg‐
                ments.

              * VmLib: Shared library code size.

              * VmPTE: Page table entries size (since Linux 2.6.10).

              * VmPMD: Size of second-level page tables (since Linux 4.0).

              * VmSwap: Swapped-out virtual memory size by anonymous private
                pages; shmem swap usage is not included (since Linux
                2.6.34).

              * HugetlbPages: Size of hugetlb memory portions.  (since Linux
                4.4).

              * Threads: Number of threads in process containing this
                thread.

              * SigQ: This field contains two slash-separated numbers that
                relate to queued signals for the real user ID of this
                process.  The first of these is the number of currently
                queued signals for this real user ID, and the second is the
                resource limit on the number of queued signals for this
                process (see the description of RLIMIT_SIGPENDING in
                getrlimit(2)).

              * SigPnd, ShdPnd: Number of signals pending for thread and for
                process as a whole (see pthreads(7) and signal(7)).

              * SigBlk, SigIgn, SigCgt: Masks indicating signals being
                blocked, ignored, and caught (see signal(7)).

              * CapInh, CapPrm, CapEff: Masks of capabilities enabled in
                inheritable, permitted, and effective sets (see
                capabilities(7)).

              * CapBnd: Capability Bounding set (since Linux 2.6.26, see
                capabilities(7)).

              * CapAmb: Ambient capability set (since Linux 4.3, see
                capabilities(7)).

              * NoNewPrivs: Value of the no_new_privs bit (since Linux 4.10,
                see prctl(2)).

              * Seccomp: Seccomp mode of the process (since Linux 3.8, see
                seccomp(2)).  0 means SECCOMP_MODE_DISABLED; 1 means SEC‐
                COMP_MODE_STRICT; 2 means SECCOMP_MODE_FILTER.  This field
                is provided only if the kernel was built with the CON‐
                FIG_SECCOMP kernel configuration option enabled.

              * Cpus_allowed: Mask of CPUs on which this process may run
                (since Linux 2.6.24, see cpuset(7)).

              * Cpus_allowed_list: Same as previous, but in "list format"
                (since Linux 2.6.26, see cpuset(7)).

              * Mems_allowed: Mask of memory nodes allowed to this process
                (since Linux 2.6.24, see cpuset(7)).

              * Mems_allowed_list: Same as previous, but in "list format"
                (since Linux 2.6.26, see cpuset(7)).

              * voluntary_ctxt_switches, nonvoluntary_ctxt_switches: Number
                of voluntary and involuntary context switches (since Linux
                2.6.23).