Unit 7 Solaris Process Control

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Unit 7 Solaris Process Control

• Randy Marchany
• VA Tech Computing Center

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ps

• The ps command lists processes running on the
  system.
• Without arguments, the command only shows the
  processes run by the current user.
• Solaris has 2 versions of the ps command.
  /usr/ucb/ps and /usr/bin/ps. /usr/ucb/ps is the
  BSD version of the command.

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ps

• ps ef will list all of the processes running on
  the system.
• Every process is assigned a unique number (PID).
• The CMD field of the output lists the actual
  command running on the system.
• There are a lot of other fields

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ps

• ps el will list the process states as well.
• O the process is currently running. Note, this
  will almost always be the ps command itself.
• S the process is sleeping, waiting for
  resources or input.
• R the process is runnable and in the run queue.
• Z the process is in a Zombie state and can only
  be cleared by a reboot. This occurs when a child
  process dies ant the parent fails to clean up
  after it.
• T process is stopped by job control. A ctl-Z
  will put a process in this state.

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prstat

• prstat command shows the running processes at a
  configured interval (5 seconds).
• Can sort the output by key values supplied by the
  s option
• Cpu sort by cpu usage
• Time sort by process execution time
• Size sort by process image size
• Rss sort by process resident set size
• Pri sort by process priority

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Killing a Process

• Sometimes you have to kill a runaway process.
• The kill command will do this but you must
  specify a signal value. This signal tells the
  process to do something.
• Solaris has 42 different signals that can be sent
  to a process. Well only look at 3 of them 1, 3,
  9.

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Killing a Process

• Trapping Signals
• A process can do 3 things when it receives a
  signal
• Ignore the signal
• Do something like close all open files and
  exiting
• Do what the signal tells it to do
• If the process has a signal handler, then it
  can intercept the signal and do what the handler
  wants with it.

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Killing a Process

• The psig command (new to Solaris 8) will print a
  list showing what the process response will be
  to each of the 47 different signals.
• There are 2 signals which cant be ignored.
• 9 aka SIGKILL forces a process to release its
  resources and die. This could cause corruption of
  data if the process is I/O intensive.

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Killing a Process

• The second signal that cant be ignored
• 23 aka SIGSTOP. This is used in shell-based job
  control and is invoked when you hit a Z. Solaris
  8 provides a pstop command which does the same
  thing.
• To resume the process, use the prun command to
  restart the process from its suspended state.

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Setting Process Priority

• The nice command allows the administrator to
  change the priority of a running process.
• Default nice value is 20. Do a ps elf and look
  at the NI field.
• Nice values range from 0-39. But they are the
  number to be added to the default value of 20.
  Example nice n 10 PID will set the nice value
  to 30. You can use negative numbers to lower the
  priority. The renice command works on running
  processes.

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Common Signals
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Killing a Process

• To see all the values for the kill command,
  enter kill l
• To send a signal, enter kill s signal pid OR
  kill signal pid
• Example
• Kill 3 pid
• pgrep command retrieves the PID of a process.