'capture-pane' return only the first line in some case about libtmux

[lwthatcher]

have you tried adding a short delay before calling capture_pane?

It seems that capture_pane returns the text it finds at the time it's called. This can lead to race conditions when commands from send_keys() or cmd() might take longer to execute than the call to capture_pane().

Example:

I encountered the same problem when using it to call a custom script:

script: my-server serve api

*This script just launches a small REST server. Once initialized it prints the version number, along with some default messages from Flask.

I also found that my .bashrc setup can contribute to some delays, my setup has a slight delay so I print a message to the console once it's finished.

no delay

pane.send_keys('my-server serve api')
stuff = pane.capture_pane()
print(stuff)

Output: [' my-server serve api']

slight delay

pane.send_keys('my-server serve api')
time.sleep(2)
stuff = pane.capture_pane()
print(stuff)

Output: [' my-server serve api', '.bashrc loaded', '<user>@<host>:/path/to/dir$ my-server serve api']

slightly longer delay

pane.send_keys('my-server serve api')
time.sleep(5)
stuff = pane.capture_pane()
print(stuff)

Output: [' my-server serve api', '.bashrc loaded', '<user>@<host>:/path/to/dir$ my-server serve api', 'LAUNCHING SERVER: (3.4.3)', ' * Serving Flask app "path/to/dir/server.py"', ' * Environment: production', ' WARNING: Do not use the development server in a production environment.', ' Use a production WSGI server instead.', ' * Debug mode: off', ' * Running on http://127.0.0.1:5050/ (Press CTRL+C to quit)']

Note: some values such <user> and <host> were altered above for privacy

[rockandska]

In fact, it seems that the command is executed if i check it manually with tmux capture-pane but the problem is that it only returns just the first line.
If i replace 'cowsay hello' with say 'ls -rtl' it works and all the lines are returned
It i replace 'cowsay hello' with 'ls -rtl | fzf', only the first line is returned too

Any ideas ?

[rockandska]

Thanks @lwthatcher , didn't tried it yet, but i indeed encounter the same behaviour with another tmux library (https://github.com/jhawthorn/ttytest) and adding a delay of 0.1 between 'send-keys' solved my problems.
I wasn't aware too at first, that 'send-keys' don't wait a return of the command and need to be test manually.
Closing since it seems related to a delay between commands.
Thanks,