pstree: Associating Child Processes

Sometimes tracking down which process spawned a child process can be an arduous task, especially when you've reached more than 5 parent processes. To alleviate some of that headache Unix/Linux has a command called pstree which will show processes in a tree format.

Example:

[[email protected] ~]# pstree  
initNetworkManagerdhclient  
  [{NetworkManager}]  
 [VBoxClient{VBoxClient}]  
 VBoxService6*[{VBoxService}]  
 abrtd  
 anacron  
 atd  
 auditdaudispdsedispatch  
   {audispd}  
  {auditd}

This is awesome if you are trying to find where a process originally spawned from. Below is a couple of flags I like to add to pstree to make it even more helpful.

-a Show command line arguments. If the command line of a process is swapped out, that process is shown in parentheses. -a implicitly disables compaction for processes but not threads.
-l Display long lines. By default, lines are truncated to the display width or 132 if output is sent to a non-tty or if the display width is unknown.
-p Show PIDs. PIDs are shown as decimal numbers in parentheses after each process name. -p implicitly disables compaction.

Example Output:

[[email protected] ~]# pstree -alp  
init,1  
 NetworkManager,1108 --pid-file=/var/run/NetworkManager/NetworkManager.pid  
  dhclient,2333 -d -4 -sf /usr/libexec/nm-dhcp-client.action -pf /var/run/dhclient-eth0.pid -lf /var/lib/dhclient/dhclient-3d1ab9ed-cb4e-442d-8a32-a953a0d58b64-eth0.lease -cf /var/run/nm-dhclient-eth0.conf eth0  
  {NetworkManager},1122  
  {NetworkManager},1147  
 VBoxClient,1806 --clipboard  
  {VBoxClient},1815  
 VBoxClient,1813 --display  
  {VBoxClient},1816  
 VBoxClient,1819 --seamless  
  {VBoxClient},1820  
 VBoxService,1375  
  {VBoxService},1376  
  {VBoxService},1377  
  {VBoxService},1378  
  {VBoxService},1379  
  {VBoxService},1380  
  {VBoxService},1381

Benjamin's specialty is keeping the lights on for mission critical systems. He is currently building applications that enable high concurrency financial transactions.

Recently Benjamin published his first book; Red Hat Enterprise Linux Troubleshooting Guide. In addition to writing, he has several Open Source projects focused on making Ops easier. These projects include Automatron, a project enabling auto-healing infrastructure for the masses.

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