nl A utility for numbering lines, either from a file, or from standard input. Number non-blank lines in a file: nl {{file}} Read from standard output: cat {{file}} | nl {{options}} - Number only the lines with printable text: nl -t {{file}} Number all lines including blank lines: nl -b a {{file}} Number only the body lines that match a basic regular expression (BRE) pattern: nl -b p'FooBar[0-9]' {{file}}