The pstree command is used to display the relationship between processes in the form of a tree diagram. It is a useful tool for system administrators to visualize the hierarchy of processes running on a Linux system.
Overview
The pstree command is used to display a tree diagram of processes on a Linux system. By default, pstree shows the entire process hierarchy, starting from the init process (PID 1). Each process is displayed as a node in the tree, and child processes are indented beneath their parent process.
Syntax
The basic syntax for the pstree command is as follows:
pstree [options] [pid]
Examples
To display the entire process hierarchy, simply run the pstree command with no arguments:
$ pstree
This will display a tree diagram of all processes running on the system.
To display the process hierarchy for a specific process, use the PID of that process as an argument:
$ pstree 1234
This will display the process hierarchy for the process with PID 1234.
Use Cases
The pstree command is useful for a variety of system administration tasks, including:
- Troubleshooting system performance issues
- Monitoring resource usage by processes
- Identifying processes that are consuming excessive resources
- Understanding the relationship between processes on a system
Options
The pstree command has several options that can be used to customize its behavior. These options are summarized in the following table:
| Option | Description |
|---|---|
-a |
Show command line arguments for each process |
-c |
Do not compress identical subtrees |
-h |
Highlight the current process and its ancestors |
-l |
Show process command line arguments in full |
-n |
Sort the process tree by PID instead of process name |
-p |
Show process PIDs in addition to process names |
-u |
Show user names in addition to process names |
Troubleshooting tips
If you encounter issues with the pstree command, the following tips may help:
- If the output is too long to fit on a single screen, consider piping the output to
lessfor easier navigation:pstree | less - If the output is difficult to read due to overlapping lines, try increasing the width of your terminal window or using a wider font.
- If you receive an error message indicating that the
pstreecommand is not found, make sure that it is installed on your system. On Debian-based systems, you can install it using the following command:sudo apt-get install psmisc
Notes
- The
pstreecommand is part of thepsmiscpackage, which may need to be installed on some Linux distributions. - The
pstreecommand can be used in conjunction with other commands, such asgreporawk, to filter or manipulate the output as needed.