Skip to content

Capture tmux Output for Debugging

Created on May 19, 2026 , last updated on May 20, 2026  •  0 views

2026   ·   tools   tmux

Easily save tmux scrollback to a file so you can review logs or share them with AI for debugging.

The Problem

When running programs inside tmux, viewing and copying output is cumbersome — you have to enter scroll mode, navigate manually, and copy-paste is unreliable for large outputs.

Solution: Capture Pane to File

In your tmux session, press Ctrl+B then : to open the command prompt, and run:

capture-pane -S -2000 ; save-buffer log.txt
Flag Meaning
-S -2000 Capture from 2000 lines above the current screen
save-buffer log.txt Save the captured content to log.txt in the current directory

Adjust -2000 to capture more or fewer lines (e.g. -S -5000 for 5000 lines, or -S - for the entire scrollback history).

Use Case

This is particularly useful when you need to debug errors but aren’t sure how to fix them — save the output to a file, then feed it to an AI tool for analysis:

# Inside tmux: Ctrl+B : capture-pane -S -2000 ; save-buffer log.txt

# Then ask Claude Code to help debug
claude "check log.txt and help me fix the errors"