Adds duck-based help50 - don't merge yet

[dmalan]

TODOs

• Remove backspaces from txt, as via col -b or sed
• Handle ctl-A and ctl-E
• Hide [1] Done... messages when backgrounded process ends, as with set +m
• Hitting Enter alone at Bash prompt results in message to duck
• Have Bash script exit early on any errors, as with set -e
• Determine why ctl-d yielded below parent shell

How to Try

1. Run:

    sudo apt update && sudo apt install -y colorized-logs
   

2. Run:

   sudo wget https://raw.githubusercontent.com/cs50/codespace/help50/etc/profile.d/duck.sh -P /etc/profile.d/
   

3. Open new terminal and run a command that yields a non-0 exit status (e.g., cd foo)

Screenshot

Implementation Details

• Uses script command to capture all stdin/stdout/stderr in a temp file, so that it can optionally be accessed after a command runs.
• Has access to (but doesn't currently use):
  • Specific argv run, from history
  • HTML-colored version of stdout/stderr, in case helpful for duck [currently using just text]
  • ANSI-colored version of stdout/stderr, in case helpful for duck [currently using just text]
  • $PWD in which command was run
  • File tree relative to $CODESPACE_VSCODE_FOLDER in case helpful for cd, etc.

[curiouskiwi]

Works as expected. The only glitch I noticed is that the first error I did after opening a new tab did not trigger the ddb. Perhaps I was too quick?

/usr/bin/ld: /lib/x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x1b): undefined reference to `main'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [<builtin>: dictionary] Error 1
speller/ $ make dictionary
/usr/bin/ld: /lib/x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x1b): undefined reference to `main'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [<builtin>: dictionary] Error 1
[1]+  Done                    command50 ddb50.ask "$prompt"
speller/ $

did also notice that sometimes, the message send to ddb (and shown in the box) has unprintable chars overwriting some of it, like

Explain this error:
$ ba��valgrind a valgrind: a: command not found

or

Explain this error:
$ j�valgrind valgrind: no program specified valgrind: Use --help for more information. 

The duck was still able to interpret correctly though.

edit to add
I reproduced the "duck doesn't get the error" problem from before. It happens if the duck sidebar isn't already opened. I switched to the explorer, then had an error in the terminal. The duck sidebar opened, but the error message was never sent to it.