pi

Display 100 decimal digits of Archimedes' constant Pi

$ pi

$ pi [number]

$ pi --bibliography

$ pi --help

$ pi --version

pi [pattern]

[pattern]
    The pattern to search for in the process names or command lines.

The pi command is a command-line utility often used to filter the output of the ps command. Instead of using grep to find process based on name, this command does it directly.
It takes a pattern as input and displays information about the processes whose names match this pattern. The primary advantage of pi over piping ps to grep is that pi avoids including itself in the output, as the grep command itself would match the provided pattern.
pi is particularly useful for quickly identifying and monitoring processes based on their name or a portion of their command line.

The pi command likely uses a combination of reading process information from the /proc filesystem and comparing process names or command lines against the provided pattern. It filters out its own process to avoid inclusion in the results.

ps(1), grep(1), top(1)