"ParseError: end of file reached" when using Textual in a pipe

[8cylinder]

When piping to a textual app, I get a ParseError: end of file reached error. There is also some random text at the beginning of the error msg (^[[?2026;4$y) and there is also some left on the command line after (2026;4$yec^C).

Everything works correctly if I don't pipe to the app.

Using this code will cause the error:

# test.py
from textual.app import App

class Test(App):
    pass

if __name__ == "__main__":
    app = Test()
    app.run()

Calling that file using any of these commands will cause the error:

echo 'x' | ./test.py
echo 'x' | python test.py
echo 'x' | textual run ./test.py

This also happens if I pipe to a demo app.

echo 'x' | textual borders

Textual Diagnostics

Versions

Name	Value
Textual	0.41.0
Rich	13.6.0

Python

Name	Value
Version	3.11.6
Implementation	CPython
Compiler	GCC 13.2.0
Executable	/home/sm/projects/prism/prism/.venv/bin/python

Operating System

Name	Value
System	Linux
Release	6.5.0-13-generic
Version	#13-Ubuntu SMP PREEMPT_DYNAMIC Fri Nov 3 12:16:05 UTC 2023

Terminal

Name	Value
Terminal Application	Unknown
TERM	xterm-256color
COLORTERM	truecolor
FORCE_COLOR	Not set
NO_COLOR	Not set

Rich Console options

Name	Value
size	width=153, height=90
legacy_windows	False
min_width	1
max_width	153
is_terminal	True
encoding	utf-8
max_height	90
justify	None
overflow	None
no_wrap	False
highlight	None
markup	None
height	None

Here is a screenshot and copy/paste of the output:

/home/sm/projects/prism/prism/.venv/lib/python3.11/site-packages/textual/drivers/linux_driver.py
:243 in _run_input_thread                                                                       
                                                                                                
  240 │   │   an exception                                                                      
  241 │   │   """                                                                               
  242 │   │   try:                                                                              
❱ 243 │   │   │   self.run_input_thread()                                                       
  244 │   │   except BaseException as error:                                                    
  245 │   │   │   self._app.call_later(                                                         
  246 │   │   │   │   self._app.panic,                                                          
                                                                                                
/home/sm/projects/prism/prism/.venv/lib/python3.11/site-packages/textual/drivers/linux_driver.py
:279 in run_input_thread                                                                        
                                                                                                
  276 │   │   │   │   for _selector_key, mask in selector_events:                               
  277 │   │   │   │   │   if mask & EVENT_READ:                                                 
  278 │   │   │   │   │   │   unicode_data = decode(read(fileno, 1024))                         
❱ 279 │   │   │   │   │   │   for event in feed(unicode_data):                                  
  280 │   │   │   │   │   │   │   self.process_event(event)                                     
  281 │   │   finally:                                                                          
  282 │   │   │   selector.close()                                                              
                                                                                                
/home/sm/projects/prism/prism/.venv/lib/python3.11/site-packages/textual/_parser.py:81 in feed  
                                                                                                
   78 │   │   │   try:                                                                          
   79 │   │   │   │   self._gen.send(self._buffer.getvalue())                                   
   80 │   │   │   except StopIteration:                                                         
❱  81 │   │   │   │   raise ParseError("end of file reached") from None                         
   82 │   │   │   while self._tokens:                                                           
   83 │   │   │   │   yield self._tokens.popleft()                                              
   84                                                                                           

[github-actions]

We found the following entry in the FAQ which you may find helpful:

• How can I select and copy text in a Textual app?

Feel free to close this issue if you found an answer in the FAQ. Otherwise, please give us a little time to review.

This is an automated reply, generated by FAQtory

[davep]

You may find this discussion helpful: #3818

[8cylinder]

Ah, that's what's going on. Thanks.

[github-actions]

Don't forget to star the repository!

Follow @textualizeio for Textual updates.

[8cylinder]

I'm adding this here for anyone else who gets this error.

Adding sys.stdin = open('/dev/tty', 'r') after reading stdin fixed it for me.

Discussed in #620 and #153.

[ValentijnvdBeek]

This work around was broken in 9a9b002, where the internal implementation switched from sys.stdin to sys.__stdin__. So starting from 0.52.0, you need to reopen sys.__stdin__