Using 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 administrative tasks, such as determining how to set process priorities.

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

• Current status of the process
• Process ID
• Parent process ID
• User ID
• Scheduling class
• Priority
• Address of the process
• Memory used
• CPU time used

The following table describes some fields that are reported by the ps command. Which fields are displayed depend on which option you choose.

Table 10-2 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 xutilization for scheduling. This field is not displayed when the -c option is used. CLS The scheduling class to which the process belongs such as 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.

Using the /proc File System and Commands

You can display detailed information about the processes that are listed in the /proc directory by using process commands. The following table lists the /proc process commands. The /procdirectory is also known as the process file system (PROCFS). Images of active processes are stored here by their process ID number.

Table 10-3 Process Commands (/proc)

Process Command Description pcred Displays process credential information pfiles Reports fstat and fcntl information for open files in a process pflags Prints /proc tracing flags, pending signals 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

 

The process tools are similar to some options of the ps command, except that the output that is provided by these commands is more detailed.

In general, the process commands do the following:

• Display more information about processes, such as fstat and fcntl, working directories, and trees of parent and child processes.
• Provide control over processes by allowing users to stop or resume them.

Managing Processes With Process Commands (/proc)

You can display detailed, technical information about processes or control active processes by using some of the process commands.

If a process becomes trapped in an endless loop, or if the process takes too long to execute, you might want to stop (kill) the process.

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

The /proc file system also provides an xwatchpoint 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 xwatchpoint facility, which means that the entire xwatchpoint process is faster.

The following restrictions have been removed when you set xwatchpoints by using the dbxdebugging tool:

• Setting xwatchpoints on local variables on the stack due to SPARC based system register windows.
• Setting xwatchpoints on multithreaded processes.

 

How to List Processes

• 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 10-1 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 the ps -ef command. This output shows that the first process that is executed when the system boots is sched (the swapper) followed by the initprocess, pageout, and so on.

$ ps -ef
 UID   PID  PPID   C    STIME TTY         TIME CMD
    root     0     0   0 18:04:04 ?           0:15 sched
    root     5     0   0 18:04:03 ?           0:05 zpool-rpool
    root     1     0   0 18:04:05 ?           0:00 /sbin/init
    root     2     0   0 18:04:05 ?           0:00 pageout
    root     3     0   0 18:04:05 ?           2:52 fsflush
    root     6     0   0 18:04:05 ?           0:02 vmtasks
  daemon   739     1   0 19:03:58 ?           0:00 /usr/lib/nfs/nfs4cbd
    root     9     1   0 18:04:06 ?           0:14 /lib/svc/bin/svc.startd
    root    11     1   0 18:04:06 ?           0:45 /lib/svc/bin/svc.configd
  daemon   559     1   0 18:04:49 ?           0:00 /usr/sbin/rpcbind
  netcfg    47     1   0 18:04:19 ?           0:01 /lib/inet/netcfgd
   dladm    44     1   0 18:04:17 ?           0:00 /sbin/dlmgmtd
  netadm    51     1   0 18:04:22 ?           0:01 /lib/inet/ipmgmtd
    root   372   338   0 18:04:43 ?           0:00 /usr/lib/hal/hald-addon-cpufreq
    root    67     1   0 18:04:30 ?           0:02 /lib/inet/in.mpathd
    root   141     1   0 18:04:38 ?           0:00 /usr/lib/pfexecd
  netadm    89     1   0 18:04:31 ?           0:03 /lib/inet/nwamd
    root   602     1   0 18:04:50 ?           0:02 /usr/lib/inet/inetd start
    root   131     1   0 18:04:35 ?           0:01 /sbin/dhcpagent
  daemon   119     1   0 18:04:33 ?           0:00 /lib/crypto/kcfd
    root   333     1   0 18:04:41 ?           0:07 /usr/lib/hal/hald --daemon=yes
    root   370   338   0 18:04:43 ?           0:00 /usr/lib/hal/hald-addon-network-discovery
    root   159     1   0 18:04:39 ?           0:00 /usr/lib/sysevent/syseventd
    root   236     1   0 18:04:40 ?           0:00 /usr/lib/ldoms/drd
    root   535     1   0 18:04:46 ?           0:09 /usr/sbin/nscd
    root   305     1   0 18:04:40 ?           0:00 /usr/lib/zones/zonestatd
    root   326     1   0 18:04:41 ?           0:03 /usr/lib/devfsadm/devfsadmd
    root   314     1   0 18:04:40 ?           0:00 /usr/lib/dbus-daemon --system
    .
        .
        .

How to Display Information About Processes

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

   # pgrep process

   where 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 that you need.

   # /usr/bin/pcommand pid

   pcommand

   Is the (/proc) command that you want to run. 

   pid

   Identifies the process ID.

Example 10-2 Displaying Information About Processes

The following example shows how to use process commands to display more information about a cron process.

# pgrep cron 1
4780
# pwdx 4780 2
4780:   /var/spool/cron/atjobs
# ptree 4780 3
4780  /usr/sbin/cron
# pfiles 4780 4
4780:   /usr/sbin/cron
  Current rlimit: 256 file descriptors
   0: S_IFCHR mode:0666 dev:290,0 ino:6815752 uid:0 gid:3 rdev:13,2
      O_RDONLY|O_LARGEFILE
      /devices/pseudo/mm@0:null
   1: S_IFREG mode:0600 dev:32,128 ino:42054 uid:0 gid:0 size:9771
      O_WRONLY|O_APPEND|O_CREAT|O_LARGEFILE
      /var/cron/log
   2: S_IFREG mode:0600 dev:32,128 ino:42054 uid:0 gid:0 size:9771
      O_WRONLY|O_APPEND|O_CREAT|O_LARGEFILE
      /var/cron/log
   3: S_IFIFO mode:0600 dev:32,128 ino:42049 uid:0 gid:0 size:0
      O_RDWR|O_LARGEFILE
      /etc/cron.d/FIFO
   4: S_IFIFO mode:0000 dev:293,0 ino:4630 uid:0 gid:0 size:0
      O_RDWR|O_NONBLOCK
   5: S_IFIFO mode:0000 dev:293,0 ino:4630 uid:0 gid:0 size:0
      O_RDWR

1. Obtains the process ID for the cron process
2. Displays the current working directory for the cron process
3. Displays the process tree that contains the cron process
4. Displays fstat and fcntl information

How to Control Processes

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

   # pgrep process

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

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

2. Use the appropriate process command to control the process.

   # /usr/bin/pcommand pid

   pcommand

   Is the process (/proc) command that you want to run. 

   pid

   Identifies the process ID.

3. Verify the process status.

   # ps -ef | grep pid

Terminating a Process (pkill, kill)

Sometimes, you might need 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. 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 most likely will crash the system.

 

How to Terminate a Process (pkill)

1. To terminate the process of another user, become root.
2. Obtain the process ID for the process that you want to terminate.

   $ pgrep process

   where process is the name of the process that you want to terminate.

   For example:

   $ pgrep netscape
   587
   566

   The process ID is displayed in the output.

   ---

   Note – To obtain process information about a Sun Ray, use the following commands:

   # ps -fu user

   This command lists all user processes.

   # ps -fu user | grep process

   This command locates a specific process for a user.

   ---

3. Terminate the process.

   $ pkill [signal] process

   signal

   When no signal is included in the pkill command-line syntax, the default signal that is used is –15 (SIGKILL). Using the –9 signal (SIGTERM) with the pkill command ensures that the process terminates promptly. However, the –9 signal should not be used to kill certain processes, such as a database process, or an LDAP server process. The result is that data might be lost.

   process

   Is the name of the process to stop.

   ---

   Tip – When using the pkill command to terminate a process, first try using the command by itself, without including a signal option. Wait a few minutes to see if the process terminates before using the pkill command with the -9 signal.

   ---

4. Verify that the process has been terminated.

   $ pgrep process

   The process you terminated should no longer be listed in the output of the pgrep command.

How to Terminate a Process (kill)

1. To terminate the process of another user, become root.
2. Obtain the process ID of the process that you want to terminate.

   # ps -fu user

   where user is the user that you want to display processes for.

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

3. Terminate the process.

   # kill [signal-number] pid

   signal

   When no signal is included in the kill command-line syntax, the default signal that is used is –15 (SIGKILL). Using the –9 signal (SIGTERM) with the kill command ensures that the process terminates promptly. However, the –9 signal should not be used to kill certain processes, such as a database process, or an LDAP server process. The result is that data might be lost.

   pid

   Is the process ID of the process that you want to terminate.

   ---

   Tip – When using the kill command to stop a process, first try using the command by itself, without including a signal option. Wait a few minutes to see if the process terminates before using the kill command with the -9 signal.

   ---

4. Verify that the process has been terminated.

   $ pgrep pid

   The process you terminated should no longer be listed in the output of the pgrep command.

Debugging a Process (pargs, preap)

The pargs command and the preap command improve process debugging. The pargs command prints the arguments and environment variables that are associated with a live process or core file. The preap command removes defunct (zombie) processes. A zombie process has not yet had its exit status claimed by its parent. These processes are generally harmless but can consume system resources if they are numerous. You can use the pargs and preap commands to examine any process that you have the privileges to examine. As superuser, you can examine any process.

Example 10-3 Debugging a Process (pargs)

The pargs command solves a long-standing problem of being unable to display with the pscommand all the arguments that are passed to a process. The following example shows how to use the pargs command in combination with the pgrep command to display the arguments that are passed to a process.

# pargs `pgrep ttymon`
579:    /usr/lib/saf/ttymon -g -h -p system-name console login:  
-T sun -d /dev/console -l 
argv[0]: /usr/lib/saf/ttymon
argv[1]: -g
argv[2]: -h
argv[3]: -p
argv[4]: system-name console login: 
argv[5]: -T
argv[6]: sun
argv[7]: -d
argv[8]: /dev/console
argv[9]: -l
argv[10]: console
argv[11]: -m
argv[12]: ldterm,ttcompat
548:    /usr/lib/saf/ttymon
argv[0]: /usr/lib/saf/ttymon

The following example shows how to use the pargs -e command to display the environment variables that are associated with a process.

$ pargs -e 6763
6763: tcsh
envp[0]: DISPLAY=:0.0