The Linux version of the ps command supports three types of format, as follows:

• Unix (POSIX) standard: In this format, options may be grouped and prefixed with a hyphen
• BSD standard: In this format, various options can be grouped, but they are not prefixed with a hyphen symbol
• GNU standard: In this format, long options are used, which are prefixed with two hyphen symbols

Various uses for the ps command, are described in the following subsections.