Assorted less(1) tips

Blog post by Tim Chase (2025-11-11), aggregated from a Reddit discussion.

Tips

1. Opening multiple files: less README.txt file.c *.md
2. Adding files after launch: :e file.h
3. Navigating between files: :n (next), :p (prev), :x (rewind to first)
4. Removing files: :d deletes current file from argument list
5. Line-number navigation: countG (e.g., 3141G jumps to line 3141)
6. Percentage navigation: count% (e.g., 75% goes to 3/4 through file)
7. Search modifiers: ! (invert match), * (cross-file), @ (from first file), @* (both)
8. Filtering: &pattern shows matching lines; &!pattern hides matching lines
9. Bookmarks: m + letter to set, ' + letter to jump back. All 52 letters available. Applies across files.
10. Bracket matching: Type (, [, or { on first screen line to jump to matching close
11. Custom match pairs: alt+ctrl+f or alt+ctrl+b followed by a pair
12. Toggling options: - + option letter (e.g., -S for line wrap, -N for line numbers)
13. External commands: !command runs shell command
14. Default options: LESS="-RNe" in .bashrc
15. Tags: ctags support (author has never used it)
16. Editing: v opens file in $VISUAL
17. Logging: o or O writes stdin to file

HN Discussion Highlights

• less +F for follow mode, Ctrl-C to break, F to resume (teeray)
• -X flag to prevent screen clearing (JayGuerette)
• & filtering for log debugging; regex supported but slow (etra0)
• -L to skip nroff preprocessing on rotated logs (inejge)
• ~/.lesskey for custom keybindings; macOS lacks this, needs Homebrew less (jez)
• ^q to quit without clearing screen, q clears it (ilyagr)
• Pipe command with marks for saving text selections to file (Rediscover)
• !bash from less as root = privilege escalation vector (GuB-42)
• OpenBSD's man provides tags to less for section jumping (somat)
• -F auto-quits if file fits on one screen; alternative pagers like most (fragmede)
• s saves piped data to file (btdmaster)
• lesspipe enables syntax highlighting and file rendering (alkh)
• Vim muscle memory transfers to less; keybindings feel intuitive (eulgro)
• PCRE support useful for code analysis; bookmarks as "microtools" (jsrcout)
• Regex engine unreasonably slow on large files (jemfinch)
• "If you want security, unset LESSOPEN" (anthk)
• LESSSECURE=1 disables dangerous features like ! (jmholla)