NAME

ps − display process status

SYNOPSIS

ps [axltpku] [ARG2 ARG3 ...]

DESCRIPTION

Ps is used to display the status of some or all of the processes currently in the operating system.  If no options are specified, the program displays a heading, followed by one line for each process which belongs to the user who has issued the ps command.  Each line has four columns, namely:
 

TIME        the total system and user mode CPU time used by the process.  The time is printed out in the form "mmm:ss", where mmm is the number of minutes and ss is the number of seconds. 
 

TTY         the name of the controlling terminal associated with the process.  If the terminal name is of the conventional form "ttyxx", the last two characters of the name are printed.  The console terminal ("/dev/console") is denoted by "co". 
 

PID         the process number of the process. 
 

COMMAND     an educated guess at the program name and arguments from the last "exec" (see EXEC(2)) performed by the process.  It is possible for a process to falsify or destroy this information, so don’t stake your life on its accuracy.  If the process is a "zombie", that is, if it has done an EXIT(2) call, but its parent process is alive and has not done a WAIT(2) for it, the COMMAND column for the process will contain the words "<PROCESS EXITING>". 
 

The "l" option is used to request a "long" listing.  The long listing has additional columns displayed before the ones listed above.  These columns are
 

SIZE        the number of kilobytes in the process image. 
 

WAITING-FOR  this column represents symbolically the state of the process.  A process in an SWAIT (long sleep) state is indicated by the name of the kernel condition which the process is waiting on.  A process in an SSLEEP (short sleep) state has the name of the condition in uppercase letters.  A number in this field indicates that the process is awaiting a condition for which ps does not have a name; the number is a kernel virtual data space address (in octal).  Other process states are indicated by: <ready> (SRUN), <stopped> (SSTOP), <newborn> (SIDL), <zombie> (SZOMB), and <empty> (SEMPTY).  A process which resides in main memory is indicated by an asterisk immediately to the left of the WAITING-FOR field. 
 

LEVEL       scheduler queue level.  The best level to be at is 31, and the worst is 0.  However, processes should normally be in the range 0-15, with only the "swapper" process (process 0) at priority 16.  The priorities 16-31 are "real-time" priorities which the system does not change.  Levels 0-15 are adjusted dynamically by the system based on program behavior. 
 

UID         the real user ID of the process owner. 
 

PPID        the process number of this process’ parent process. 
 

The "a" option indicates that a list of processes for all user ID’s is to be displayed;  the "x" option causes processes with no controlling terminal to be listed.  The "t" option indicates that processes for a given terminal (specified by a later argument) are to be listed.  If no argument or a null argument corresponds to the "t" option, processes for all terminals are listed.  The format of the additional argument is XX where /dev/ttyXX is the name of the terminal’s character special device file. 
 
The "p" option indicates that information is to be displayed concerning a particular process, whose process number is specified by a later argument.
 
The "k" option allows the user to specify that an alternate core file is to be used instead of "/dev/mem".  Similarly, the "u" option indicates that an alternate "namelist" file is to be used instead of "/unix". Only the superuser is permitted to make use of the "k" and "u" options. These options are normally used to perform autopsies on system core dumps.

FILES

/unixdefault system namelist
/dev/memdefault core image file
/devsearched to find swap device and tty names

SEE ALSO

kill(1), pstat(1), nice(1), nice(2). 

NOTES

Since the system is not affected by ps, things can change while ps is running; thus, the picture it gives is only an approximation to a snapshot of the system status. 

7th Edition