What are the uses of pipes in UNIX?

Piping in unix allows the user to set the output of a specific operation as input to another. The piping of output from one file to another is performed by using the | symbol.

For ex.

uhunix% w | grep username

This command would allow the user to check if the specified user is logged in or not. When pipes are used in combination with redirection it gives the user the powerful ability to manipulate long operations in short steps.

For ex.

uhunix% ls | grep vi > vi.files

This command would result in the creation of a vi.files which would consist of the names of all the files in the current directory with a vi in their names.