Is it possible to directly edit scrollback buffer?

[leelavg]

Hi,

• I've spent more than a couple of hours to achieve $title and couldn't do it and had to settle with way lesser functionality
• Posting the question here in hope to find a combination that works

Usecase:

1. Assume I've a relatively large log file with below important info

$ sed -n '1345,1349p' split-1-failure 
003087 COMM (S3, leader   , 2) log entry commited {T:2, C:5119;} at {5}
3: log map[1:2930 2:1185 3:9368 4:6549 5:5119]; server map[1:2930 2:1185 3:9368 4:6549 5:5119 6:2027 7:6154 8:2571]
3: log map[1:2930 2:1185 3:9368 4:6549 5:5119]; server map[1:2930 2:1185 3:9368 4:6549 5:5119 6:2027 7:6154 8:2571]
3: log map[1:2930 2:1185 3:9368 4:6549 5:5119]; server map[1:2930 2:1185 3:9368 4:6549 5:5119 6:2027 7:6154 8:2571]
apply error: commit index=6 server=3 7647 != server=4 2027

$ grep --color=never {6} split-1-failure
000585 ACKL (S0, leader   , 1) log req ack {T:1, C:7524;} at {6}
001044 ACKL (S3, leader   , 2) log req ack {T:2, C:7647;} at {6}
002700 ACKL (S4, leader   , 7) log req ack {T:7, C:2027;} at {6}
002716 APND (S2, follower , 7) log entry appended {[T:7, C:2027; T:7, C:6154;]} at {6}
002725 COMM (S4, leader   , 7) log entry commited {T:7, C:2027;} at {6}
002725 APND (S1, follower , 7) log entry appended {[T:7, C:2027; T:7, C:6154;]} at {6}
002728 APND (S1, follower , 7) log entry appended {[T:7, C:2027; T:7, C:6154; T:7, C:2571;]} at {6}
002731 APND (S2, follower , 7) log entry appended {[T:7, C:2027; T:7, C:6154; T:7, C:2571;]} at {6}
002804 COMM (S2, follower , 7) log entry commited {T:7, C:2027;} at {6}
002819 COMM (S1, follower , 7) log entry commited {T:7, C:2027;} at {6}

2. The file cat split-1-failure fits in tmux scrollback buffer
3. Now, I want to edit the command output directly, basically want to add some markers in the buffer and have them persist if I scrollback again, is it possible?
4. I had to settle with only copying parts of the log file into a buffer and edit or add markers in that buffer however this is no where near to just scrollback the terminal and view the markers

The feature is similar to https://www.youtube.com/embed/dP1xVpMPn8M?start=954&end=1004

thanks in advance!

[ericpruitt]

I don't know of a native way to do this, but I wrote this shell script:

#!/bin/sh
set -e
trap 'rm -f -- "${scrollback:-}"' EXIT
scrollback="$(mktemp)"
tmux capture-pane -p -S - -E - > "$scrollback"

while :; do
    $VISUAL "$scrollback" && break
done
clear
tmux clear-history
cat "$scrollback"

You have would type edit-pane (or whatever you choose to call the script) at your shell's prompt. I wasn't able to figure out a way to replace the contents of pane asynchronously. If such an option exists, it might be possible to bind a properly crafted edit command to a copy-mode key sequence to make the process more seamless and also open the editor at the exact position of the cursor.

I don't know what editor you're using, but if it's Vi or Vim, you can add "+" after $VISUAL to have it position the cursor at the bottom of the file. Adding "-e" to capture-pane can also be used to preserve escape sequences, but you'd only want to do that if your editor supports processing ANSI sequences.

[leelavg]

Thanks a lot for taking time and providing a script to start with.

I use foot + tmux + helix-editor, however I get what you are saying. I believe it is plan9 os/utils in the video which takes everything is a file up a notch and can allow these workflows 😅.

[ericpruitt]

Yes, that is Plan 9. The userspace tools have been ported to work on modern operating systems and can be found at https://9fans.github.io/plan9port/, but I don't think the 9term will work well with tmux out of the box.

EDIT: I didn't pay close attention to the video, and I see now that's Acme, not 9term.

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