To display line numbers in less, pass the -N flag when opening a file: less -N file.txt. If you have already opened a file in less, type -N followed by Enter to toggle line numbers on or off. For a permanent default, set the LESS environment variable: export LESS='-N' in your shell profile.

Using the -N Flag

The -N option adds a line number column to the left of every line. Numbers update dynamically as you scroll, and they do not become part of the text if you pipe the output elsewhere.

1# Open a file with line numbers
2less -N /var/log/syslog
3
4# Combine with other flags
5less -NS /etc/nginx/nginx.conf    # -S disables line wrapping
6less -NM /var/log/auth.log        # -M shows a more detailed prompt
7less -Ni /etc/hosts               # -i enables case-insensitive search

The line number column is typically 7 characters wide. On narrow terminal windows, this reduces the visible text width. If that is a concern, toggle line numbers on only when you need them.

Toggling Line Numbers Inside less

If you opened a file without -N and realize you need line numbers, you do not need to exit and reopen the file.

1# While viewing a file in less:
2
3-N        then press Enter    → Toggle line numbers on/off
4-n        then press Enter    → Same toggle (alternative key)
5
6# To jump to a specific line number:
750g       → Jump to line 50
8100G      → Jump to line 100 (capital G also works)
9
10# To see your current position:
11=         → Shows current line range, byte position, and percentage

The toggle is immediate. Pressing -N once turns line numbers on; pressing it again turns them off. This is useful when you want line numbers temporarily for referencing a specific line in a code review or bug report.

Making Line Numbers the Default

If you always want line numbers, set the LESS environment variable in your shell configuration file.

1# For bash (~/.bashrc or ~/.bash_profile)
2export LESS='-N'
3
4# For zsh (~/.zshrc)
5export LESS='-N'
6
7# Combine multiple default options
8export LESS='-NRiMS'
9# -N  line numbers
10# -R  interpret ANSI color codes (essential for colored output like git diff)
11# -i  case-insensitive search (unless search contains uppercase)
12# -M  more verbose prompt
13# -S  disable line wrapping (scroll horizontally instead)
14
15# Apply without restarting the terminal
16source ~/.bashrc

With LESS set, every invocation of less (including those triggered by man, git log, git diff, and other tools that use less as a pager) will include line numbers by default.

Overriding the Default for a Single Command

If you have set -N as the default but want to suppress it for one command:

1# Override the LESS variable for a single invocation
2LESS='' less file.txt
3
4# Or pass +N to turn off line numbers explicitly
5less +N file.txt

The + prefix inverts a flag. +N disables line numbers regardless of the LESS environment variable.

Useful Navigation Commands

Line numbers become more powerful when combined with navigation commands.

Jumping to a Line from the Command Line

You can open less at a specific line number directly:

1# Open file at line 150
2less +150 file.txt
3
4# Open file at line 150 with line numbers displayed
5less -N +150 file.txt
6
7# Open file at the first occurrence of a pattern
8less +/ERROR /var/log/syslog

This is particularly useful when a compiler error or stack trace references a specific line number and you want to navigate there immediately.

Using less as a Pager for Other Tools

Many command-line tools use less as their default pager. Line numbers can be especially helpful in these contexts.

1# Git log with line numbers
2git log | less -N
3
4# Man pages with line numbers
5man bash | less -N
6
7# Viewing a large JSON file with jq and line numbers
8jq '.' large-file.json | less -N
9
10# Viewing compiler output
11make 2>&1 | less -N

Configuring less as the Default Pager

1# Set less as the default pager with your preferred options
2export PAGER='less -NR'
3
4# Git-specific pager configuration
5git config --global core.pager 'less -NR'
6
7# Man-specific pager
8export MANPAGER='less -NiRS'

Alternatives to -N for Line Context

Sometimes you do not need permanent line numbers but want to see which line you are on. These alternatives may be sufficient:

1# Show line numbers only in the prompt (no column in the text)
2less -M file.txt
3# The prompt at the bottom shows "lines X-Y/TOTAL"
4
5# Use cat -n to add line numbers to the text itself
6cat -n file.txt | less
7# Line numbers are part of the text, searchable with /
8
9# Use nl for more control over number formatting
10nl -ba file.txt | less
11# -ba numbers all lines including blank ones
12
13# Use grep -n to show line numbers for matching lines
14grep -n "pattern" file.txt | less

The key advantage of less -N over piping through cat -n is that less -N shows true line numbers that update as you scroll, and the numbers are not part of the searchable text. With cat -n, the numbers are baked into the content, which means searching for 42 would match line number 42, line 142, and any content containing "42."

Common Pitfalls

• Confusing -N (line numbers) with N (repeat search backward). The -N is typed at the less command prompt with a leading dash. Capital N without a dash repeats the last search in the reverse direction. These are completely different operations.
• Setting LESS='-N' and getting unexpected behavior in git diff. Git diff output is paged through less. With -N, every diff line gets a line number, which can be confusing because diff already has its own line numbering. Use git config --global core.pager 'less -R' to set a Git-specific pager without -N.
• Expecting line numbers to appear in piped output. When you pipe less output to another command (e.g., less -N file.txt | grep something), line numbers are not included because less only adds them for display, not to the output stream.
• Not using -R alongside -N for colored content. Without -R, ANSI color escape codes appear as raw text (e.g., ^[[32m). Always combine -N with -R when viewing colored output: less -NR.
• Forgetting that +N disables line numbers. The + prefix inverts the flag. If your LESS environment variable includes -N and you open a file with less +N file.txt, line numbers will be off. This is intentional but can be confusing.
• Using lesskey configuration that conflicts with -N. Custom lesskey bindings can remap the -N toggle. If -N does not work as expected inside less, check ~/.lesskey or ~/.config/lesskey for conflicting bindings.

Summary

Display line numbers in less with less -N filename, toggle them inside an open session by typing -N and pressing Enter, or make them permanent by adding export LESS='-N' to your shell profile. Combine with -R for colored output, -S for no-wrap mode, and -M for verbose prompts. Use Ng to jump to line N, = to check your current position, and +/pattern to open at a search hit. For Git and other tools that use less as a pager, configure the pager separately to avoid line numbers cluttering diff output. The -N flag adds display-only line numbers that do not affect the text content, searches, or piped output.