Number Lines With nl

Prefix each line with a number, with control over formatting and ranges.

LinuxtextcliLow risk

Run nl -ba file.txt to number all lines including blanks.

01Command

Command

$ nl -ba file.txt

02What it does

nl numbers input for review, logs or cross-referencing, and unlike cat -n it can skip blank lines, set the number format and restart numbering at sections. It is a review aid built for pipelines.

03Risk

RiskLow risk

RequirementsPreinstalled on Linux (GNU coreutils)

!Warning: Numbering is textual output only; it does not modify the source file.

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

nl.1.en.html manual page (Debian bookworm)
Debian · technical · 2026-09-20
Evidence: Documents nl, which numbers lines of input.

Last verified: 2026-10-13 · Category: Developer

06Related solutions

Create and Apply Patches with diff -u and patch

Linuxdiffpatchtext

Generate a unified diff between two files, apply it to another copy with patch, and reverse it with patch -R.

Low risk ✓ 2026-09-17