cmd2 and a-Shell about cmd2

[kotfu]

I messed around in a-shell for a minute. You might try this:

• create a new directory ~/Documents/a-shell-bin
• add that new directory to your PATH environment variable
• create the no-op version of stty referenced above by:

$ cd ~/Documents/a-shell-bin
$ cat > stty
#
exit 0

• type Control-D to exit cat and write the file
• change ~/Documents/a-shell-bin to be executable by everyone (i.e. chmod 755 stty)

[kotfu]

What operating system are you using? Would you mind posting your simple program? With this info I'll bet I can chase down your problem.

[tthkbw]

@kotfu

I am running the program under a-Shell on a iPad Pro with iOS 16.3.1

Here's the code:

import cmd2

def setprompt():
    global current_book

    promptstr = f"<My Prompt:> "
    CmdBooks.prompt = promptstr

class CmdBooks(cmd2.Cmd):
    """Simple Command Processor"""

    def default(self, line):
        print("Invalid command; try again")

    def do_one(self, line):
        print("This is command one.")

                 
    def do_two(self, line):
        print("This is command two.")

if __name__ == "__main__":
    CmdBooks().cmdloop()

[kotfu]

Gotcha. Here's what's happening: occasionally control characters in the printed output can mess up your terminal. This only seems to happen on linux/bsd/unix variants. So after each command has run, cmd2 resets the terminal using the stty sane command. It only tries to execute this if the operating system isn't windows. In all our experience to date, all non-windows operating systems have included the stty command. I downloaded a-shell, and sure enough, the kernel identifes itself as darwin (a bsd variant), but there is no stty command in the default install. So when you run a command cmd2 tries to clean up the terminal, and a-shell complains because it doesn't include a stty command.

As for potential solutions, I'm not sure how we could get cmd2 to tell it was running inside of a-shell. The kernel a-shell reports looks like macOS to python. So here's some things you could try:

• see if there is a way to install a working stty program in a-shell
• create a shell script named stty and put it in your a-shell path. The script would contain something like:

# do nothing
exit 0

That way when cmd2 tries to run stty it will be able to run it and not generate any error message.

Another alternative might be to try iSH on your ipad. It includes a working stty program.

Hope this helps.

[tthkbw]

@kotfu thank you for the help. I have played around with this today and so far haven't been successful in generating a no-op version of stty, but I'm still working on it.

With respect to determining the presence of a-Shell, I had done that for some options in my script. a-Shell has an environment variable $APPDIR that is the location of the a-Shell.app. So I did:

import os
appdir = os.getenv("APPDIR")
if appdir != None and "a-Shell" in appdir:
    in_ashell = True
else:
    in_ashell = False

For now I have modified the cmd2.py file on my iPad so that it doesn't run stty if I find I am in a-Shell--same as it does if cmd2 is running in Windows.

[tthkbw]

Thanks. Before I saw your latest, I compiled a simple C program called stty:

int main(void) {
    return(0)
}

I compiled it, put it in ~/Documents/bin, and now unmodified cmd2 doesn't complain when run!

Thanks a lot for helping with this.

[kotfu]

Glad you were able to get it sorted, and it looks like there may be some interest from a-shell in doing something more standard to resolve the issue.