tldr/pages/common/nl.md

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}}