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System Administration Guide: Advanced Administration

Commands for Managing System Processes (Overview)

The following table describes the commands for managing system processes.

Table 23–1 Commands for Managing Processes

Command  

Man Page 

Description 

ps, pgrep, prstat

ps(1), pgrep(1), and prstat(1M)

Checks the status of active processes on a system, as well as displays detailed information about the processes 

dispadmin

dispadmin(1M)

Lists default scheduling policies 

priocntl

priocntl(1)

Assigns processes to a priority class and manages process priorities 

nice

nice(1)

Changes the priority of a timesharing process 

psrset

psrset(1M)

Binds specific process groups to a group of processors rather than to just a single processor 

The Solaris Management Console's Processes Tool enables you to manage processes with a user-friendly interface. For information on using and starting the Solaris Management Console, see “Working With the Management Console (Tasks)” in System Administration Guide: Basic Administration.

The ps Command

The ps command enables you to check the status of active processes on a system, as well as display technical information about the processes. This data is useful for such administrative tasks as determining how to set process priorities.

Depending on which options you use, the ps command reports the following information:

The following table describes some fields that are reported by the ps command. Which fields are displayed depend on which option you choose. For a description of all available options, see ps(1).

Table 23–2 Summary of Fields in ps Reports

Field 

Description 

UID

The effective user ID of the process's owner. 

PID

The process ID. 

PPID

The parent process ID. 

C

The processor utilization for scheduling. This field is not displayed when the -c option is used.

CLS

The scheduling class to which the process belongs: real-time, system, or timesharing. This field is included only with the -c option.

PRI

The kernel thread's scheduling priority. Higher numbers indicate a higher priority. 

NI

The process's nice number, which contributes to its scheduling priority. Making a process “nicer” means lowering its priority.

ADDR

The address of the proc structure.

SZ

The virtual address size of the process. 

WCHAN

The address of an event or lock for which the process is sleeping.  

STIME

The starting time of the process (in hours, minutes, and seconds). 

TTY

The terminal from which the process (or its parent) was started. A question mark indicates that there is no controlling terminal. 

TIME

The total amount of CPU time used by the process since it began. 

CMD

The command that generated the process.  

How to List Processes

You can use the ps command to list all the processes on a system. 


$ ps [-efc]

ps

Displays only the processes that are associated with your login session. 

-ef

Displays full information about all the processes that are being executed on the system. 

-c

Displays process scheduler information. 

Example—Listing Processes

The following example shows output from the ps command when no options are used. 


$ ps
   PID TTY      TIME COMD
  1664 pts/4    0:06 csh
  2081 pts/4    0:00 ps

The following example shows output from ps -ef. This output shows that the first process that is executed when the system boots is sched (the swapper) followed by the init process, pageout, and so on. 


$ ps -ef
     UID   PID  PPID  C    STIME TTY      TIME CMD
    root     0     0  0   Dec 20 ?        0:17 sched
    root     1     0  0   Dec 20 ?        0:00 /etc/init -
    root     2     0  0   Dec 20 ?        0:00 pageout
    root     3     0  0   Dec 20 ?        4:20 fsflush
    root   374   367  0   Dec 20 ?        0:00 /usr/lib/saf/ttymon
    root   367     1  0   Dec 20 ?        0:00 /usr/lib/saf/sac -t 300
    root   126     1  0   Dec 20 ?        0:00 /usr/sbin/rpcbind
    root    54     1  0   Dec 20 ?        0:00 /usr/lib/sysevent/syseventd
    root    59     1  0   Dec 20 ?        0:00 /usr/lib/picl/picld
    root   178     1  0   Dec 20 ?        0:03 /usr/lib/autofs/automountd
    root   129     1  0   Dec 20 ?        0:00 /usr/sbin/keyserv
    root   213     1  0   Dec 20 ?        0:00 /usr/lib/lpsched
    root   154     1  0   Dec 20 ?        0:00 /usr/sbin/inetd -s
    root   139     1  0   Dec 20 ?        0:00 /usr/lib/netsvc/yp/ypbind ...
    root   191     1  0   Dec 20 ?        0:00 /usr/sbin/syslogd
    root   208     1  0   Dec 20 ?        0:02 /usr/sbin/nscd
    root   193     1  0   Dec 20 ?        0:00 /usr/sbin/cron
    root   174     1  0   Dec 20 ?        0:00 /usr/lib/nfs/lockd
  daemon   175     1  0   Dec 20 ?        0:00 /usr/lib/nfs/statd
    root   376     1  0   Dec 20 ?        0:00 /usr/lib/ssh/sshd
    root   226     1  0   Dec 20 ?        0:00 /usr/lib/power/powerd
    root   315     1  0   Dec 20 ?        0:00 /usr/lib/nfs/mountd
    root   237     1  0   Dec 20 ?        0:00 /usr/lib/utmpd
    .
    .
    .

The /proc File System and Commands

Process tools that are available in the /usr/proc/bin directory display highly detailed information about the processes listed in the /proc directory. (The /proc directory is also known as the process file system (PROCFS).) Images of active processes are stored here by their process ID number.

The process tools are similar to some options of the ps command, except that the output that is provided by the tools is more detailed. In general, the process tools do the following:

Managing Processes With /proc Tools

You can display detailed, technical information about or control active processes by using some of the process tool commands that are contained in the /usr/proc/bin directory. Table 23–3 lists some of the /proc tools.

If a process becomes trapped in an endless loop, or if it takes too long to execute, you might want to stop (kill) the process. For more information about stopping processes using the pkill command, see Chapter 23, Managing System Processes (Tasks).

The /proc file system is a directory hierarchy that contains additional subdirectories for state information and control functions.

It also provides a watchpoint facility that is used to remap read and write permissions on the individual pages of a process's address space. This facility has no restrictions and is MT-safe.

Debugging tools have been modified to use /proc's watchpoint facility, which means that the entire watchpoint process is faster.

The following restrictions have been removed when setting watchpoints by using the dbx debugging tool:

For more information, see proc(4), core(4), and mdb(1).

Table 23–3 /usr/proc/bin Tools

Process Tool 

Description 

pcred

Displays process credential information 

pfiles

Reports fstat and fcntl information for open files in a process

pflags

Prints /proc tracing flags, pending and held signals, and other status information

pldd

Lists the dynamic libraries that are linked into a process 

pmap

Prints the address space map of each process 

psig

Lists the signal actions and handlers of each process 

prun

Starts each process 

pstack

Prints a hex+symbolic stack trace for each lwp in each process 

pstop

Stops each process 

ptime

Times a process by using microstate accounting 

ptree

Displays the process trees that contain the process 

pwait

Displays status information after a process terminates 

pwdx

Displays the current working directory for a process 

For more information, see proc(1).

Note –

To avoid typing long command names, add the process tool directory to your PATH variable. Then, you can run process tools by entering only the last part of each file name (for example, pwdx instead of /usr/proc/bin/pwdx).

How to Display Information About Processes

  1. Obtain the process ID of the process you want to display more information about. 


    # pgrep process

    process is the name of the process you want to display more information about.

    The process ID is displayed in the first column of the output.

  2. Display the process information you need. 


    # /usr/proc/bin/pcommand pid

    pcommand

    Process tool command that you want to run. Table 23–3 lists these commands.

    pid

    Indicates the process ID. 

Example—Displaying Information About Processes

The following example shows how to use process tool commands to display more information about an lpsched process. First, the /usr/proc/bin path is defined to avoid typing long commands. Next, the identification number for the lpsched process is obtained. Finally, output from three process tool commands is shown. 


# PATH=$PATH:/usr/proc/bin
# export PATH 1
# pgrep lpsched 2
213
# pwdx 213 3
213:    /
# ptree 213 4
213   /usr/lib/lpsched
# pfiles 213 5
213:    /usr/lib/lpsched
  Current rlimit: 4096 file descriptors
   0: S_IFIFO mode:0000 dev:270,0 ino:67 uid:0 gid:0 size:0
      O_RDWR
   1: S_IFIFO mode:0000 dev:270,0 ino:67 uid:0 gid:0 size:0
      O_RDWR
   3: S_IFCHR mode:0666 dev:136,0 ino:35882 uid:0 gid:3 rdev:21,0
      O_WRONLY FD_CLOEXEC
   4: S_IFDOOR mode:0444 dev:275,0 ino:18526 uid:0 gid:0 size:0
      O_RDONLY|O_LARGEFILE FD_CLOEXEC  door to nscd[208]
   5: S_IFREG mode:0664 dev:136,0 ino:64648 uid:71 gid:8 size:0
      O_WRONLY

  1. Adds the /usr/proc/bin directory to the PATH variable

  2. Obtains the process identification number for lpsched

  3. Displays the current working directory for lpsched

  4. Displays the process tree that containslpsched

  5. Displays fstat and fcntl information

How to Control Processes

  1. Obtain the process ID of the process you want to control.


    # pgrep process

    process is the name of the process you want to control.

    The process identification number is in the first column of the output.

  2. Use the appropriate /usr/proc/bin command to control the process.


    # /usr/proc/bin/pcommand pid

    pcommand

    Process tool command you want to run. Table 23–3 lists these commands.

    pid

    Identifies the process ID. 

  3. Verify the process status.


    # pgrep PID

Example—Controlling Processes

The following example shows how to use process tools to stop and restart dtpad.


# PATH=$PATH:/usr/proc/bin
# export PATH 1
# pgrep dtpad 2
2921
# pstop 2921 3
# prun 2921 4

  1. Adds the /usr/proc/bin directory to the PATH variable

  2. Obtains the process identification number for dtpad

  3. Stops the dtpad process

  4. Restarts the dtpad process

Killing a Process (pkill)

Sometimes, it is necessary to stop (kill) a process. The process might be in an endless loop, or you might have started a large job that you want to stop before it is completed. You can kill any process that you own, and superuser can kill any process in the system except for those processes with process IDs of 0, 1, 2, 3, and 4. Killing these processes might crash the system.

For more information, see pgrep(1).

How to Kill a Process

  1. (Optional) To kill a process that belongs to another user, become superuser.

  2. Obtain the of the process ID of the process you want to stop.


    $ pgrep process

    process is the name of the process you want to display more information about.

    The process identification number is displayed in the first column of the output.

  3. Stop the process.


    $ pkill [-9] pid

    -9

    Ensures that the process terminates promptly. 

    pid

    Process ID to stop. 

  4. Verify that the process has been stopped.


    $ pgrep pid