People seldom use the command on Linux machines nowadays. We are accustomed to an equivalent command , that for eons was slightly more convenient. There is a reason, though, to use command much more often. Especially when we want to figure out something less routine and less obvious.

Sometimes the two commands print the same text, verbatim. However, it is not always so. Generally and often, they display different documents, that different people wrote at different times. Information presented vaguely or incomprehensible in one of them often is expressed much more clearly in another. Or important details are explained only in one of the sources. Or a code sample is provided. For example, commands and complement one another nicely.

Some subjects are covered only by . On my machine does not return anything useful, while displays a rich documentation on command .

By the way, with recent distros, became as convenient as . There is no need anymore to pipe to : does exactly the same as You can check if it works on your machine.