PSSH, short for Parallel SSH, is a Linux command-line tool that allows for parallel execution of commands on multiple remote machines. It is a powerful tool for system administrators who need to manage a large number of machines simultaneously. With PSSH, you can execute commands on multiple machines at once, which saves time and effort.
Overview
The syntax for the PSSH command is as follows:
pssh [OPTIONS] command
The command argument is the command you want to execute on the remote machines. PSSH reads a list of hosts from a file or from the command line and executes the command on each of them in parallel. You can specify the hosts in a file or on the command line. Here are some examples:
# Execute the 'uptime' command on multiple hosts
pssh -h hosts.txt uptime
# Execute the 'ls' command on multiple hosts and save the output to a file
pssh -h hosts.txt -o output.txt ls
In the first example, PSSH reads the list of hosts from the hosts.txt file and executes the uptime command on each of them. In the second example, PSSH executes the ls command on each of the hosts and saves the output to the output.txt file.
PSSH also supports a number of options that allow you to customize the behavior of the command. Here are some of the most commonly used options:
Options
| Option | Description |
|---|---|
-h |
Specifies a file containing a list of hosts to execute the command on. |
-H |
Specifies a comma-separated list of hosts to execute the command on. |
-l |
Specifies the username to use when connecting to the remote hosts. |
-o |
Specifies the output file to save the command output to. |
-p |
Specifies the number of parallel connections to use. |
-t |
Specifies the timeout for each command. |
-A |
Enables authentication agent forwarding. |
-x |
Specifies a list of options to pass to SSH. |
Troubleshooting Tips
Here are some common issues you may encounter when using PSSH and how to troubleshoot them:
- PSSH hangs when connecting to a host: This could be caused by a firewall blocking the connection. Make sure that the necessary ports are open on the remote host.
- Authentication fails: Make sure that you have the correct credentials and that the SSH key is properly configured on the remote host.
- Command output is not as expected: Check the command syntax and make sure that the command is being executed correctly on the remote hosts.
- PSSH crashes or produces unexpected errors: Make sure that you are using the latest version of PSSH and that all dependencies are installed correctly.
Notes
- PSSH is a powerful tool, but it should be used with caution. Make sure that you have the proper authorization to execute commands on the remote hosts.
- Always test PSSH on a small number of hosts before using it on a larger scale.
- PSSH is not installed by default on most Linux distributions, so you may need to install it manually.