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).