You probably know command substitution. Command substitution executes a command and uses its output as a variable on the shell. The operator for this is either the backtick operator. But did you also know that there is a counterpart of command substitution? This counterpart is called process substitution.
Pipes are used very often on UNIX systems. They connect two programs in that way that the STDOUT of the first program becomes the STDIN of the second program.
