How to increase the scrollback buffer in PuTTY

PuTTY keeps a scrollback history so earlier terminal output remains available after it scrolls off-screen. Increasing the scrollback buffer helps when long commands produce lots of output, when older lines need copying, or when intermittent errors must be reviewed without rerunning the command.

Lines of scrollback controls how much text PuTTY stores locally in memory for the current terminal window. This does not change remote logging on the server, and it does not increase what the remote host records in syslog, event logs, or audit trails.

The scrollback size is stored in the selected session profile, so different servers can have different values. Larger scrollback values consume more memory during long-running sessions, and options like Reset scrollback on keypress can erase history unexpectedly if enabled.

1. Launch PuTTY.
2. Select the session profile to modify under Saved Sessions, or select Default Settings to change the baseline for new sessions.

   Default Settings affects sessions created later and does not overwrite existing saved profiles unless they are edited and saved.

3. Click Load to populate settings for the selected profile.
4. Open the Window category in the left tree.
5. Set Lines of scrollback to the required number of lines.

   Values like 5000 to 20000 work well for most troubleshooting sessions without excessive memory use.

6. Optional: Enable Display scrollbar to show a scroll bar on the terminal window.
7. Optional: Disable Reset scrollback on keypress to avoid clearing scrollback history when a key is pressed.
8. Return to the Session category.
9. Confirm a session name is present in Saved Sessions.

   Without a name, the change applies only to the current configuration view and is not saved as a reusable profile.

10. Click Save to persist the new scrollback setting for that profile.
11. Click Open to connect using the updated settings.
12. Run a command that prints several thousand lines.

    $ seq 1 5000
    1
    2
    3
    ##### snipped #####
    4998
    4999
    5000

13. Scroll back to the first lines of output to confirm the larger scrollback buffer is active.

    Shift+Page Up scrolls the PuTTY window without sending the keypress to the remote host.