Linux process Status

Often, when we see the process of PS, we can see the Stat column, indicating the status of the process;

[[Email protected] ~]# PS Axu

USER PID%cpu%MEM VSZ RSS TTY STAT START time COMMAND

Root 1 0.0 0.0 10368 148? Ss 0:02 init [3]

Root 2 0.0 0.0 0 0? s< 0:00 [migration/0]

Root 3 0.0 0.0 0 0? SN 0:00 [ksoftirqd/0]

Root 4 0.0 0.0 0 0? s< 0:00 [watchdog/0]

Root 5 0.0 0.0 0 0? s< 0:03 [events/0]

Root 6 0.0 0.0 0 0? s< 0:00 [Khelper]

Root 11 0.0 0.0 0 0? s< 0:00 [Kthread]

Root 15 0.0 0.0 0 0? s< 0:01 [kblockd/0]

Root 16 0.0 0.0 0 0? s< 0:00 [Kacpid]

Root 60 0.0 0.0 0 0? s< 0:00 [cqueue/0]

Root 1262 0.0 0.1 10128 576? Ss 0:01 syslogd-m 0

Root 1265 0.0 0.0 3824 288? Ss 0:00 Klogd-x

NSCD 1274 0.0 0.1 129572 952? SSL 0:09/USR/SBIN/NSCD

Root 1294 0.0 0.1 62648 768? Ss 0:00/usr/sbin/sshd

NTP 1307 0.0 1.0 19428 5120? SLs 0:02 ntpd-u ntp:ntp-p/var/run/ntpd.pid-g

Root 1331 0.0 0.2 74828 1152? Ss 0:00 Crond

Root 1336 0.0 0.0 31628 68? SSL 0:00/USR/SBIN/GSHELLD

Root 1345 0.0 0.1 3808 520 tty1 ss+ the 0:00/sbin/mingetty tty1

Root 1346 0.0 0.1 3808 520 Tty2 ss+ the 0:00/sbin/mingetty tty2

Root 2903 0.0 1.8 286532 9352? Sl 15:56/usr/local/aegis/alihids/alihids

Root 3480 0.0 0.3 77528 1944? Ss Jan05 0:00 screen-s Anders.zhangw

Root 3481 0.0 0.3 66084 1592 PTS/3 ss+ Jan05 0:00/bin/bash

Root 3493 0.0 0.3 66184 1644 PTS/4 ss+ Jan05 0:00/bin/bash

Root 3505 0.0 0.3 66084 1584 PTS/5 ss+ Jan05 0:00/bin/bash

Root 7527 0.0 0.3 77208 1736? Ss 0:00 screen-s Anders.zhangw

Root 7528 0.0 0.3 66084 1576 PTS/1 ss+

Root 7540 0.0 0.3 66084 1572 PTS/2 ss+

Root 12893 0.0 0.0 0 0? S Jan16 0:00 [Pdflush]

Root 12895 0.0 0.0 0 0? S Jan16 0:00 [Pdflush]

Root 15075 0.0 0.6 88080 3316? Ss 16:50 0:00 sshd: [Email protected]/0

Root 15079 0.0 0.3 66088 pts/0 Ss 16:50 0:00-bash

Root 15105 0.0 0.1 65608 988 pts/0 r+ 16:54 0:00 PS Axu

So, what does the status of the process mean?

D uninterruptible sleep (usually IO)

R running or runnable (on run queue)

S interruptible sleep (waiting for a event to complete)

T stopped, either by a job control signal or because it's being traced

W paging (not valid since the 2.6.xx kernel)

X dead (should never be seen)

Z Defunct ("zombie") process, terminated but not reaped by its parent

For BSD formats and when the STAT keyword are used, additional characters may be displayed:

< High-priority (not nice-to-other users)

N low-priority (Nice-to-other users)

L have pages locked to memory (for real-time and custom IO)

S is a session leader

L was multi-threaded (using Clone_thread, like NPTL pthreads do)

+ is in the foreground process group

Now, we can discuss the status change of Linux process in detail .... All of a sudden someone called to eat, then continue to eat after the amount

Linux process Status