"No Shell Available"

Targets macOS
1

I have a macOS Web app which runs a shell command every two hours to check if a SMTP server is alive. The command is simple, just sending the ‘QUIT’ command to the SMTP server to see if it replies as expected.

It’s been running now for about 13 days, every two hours. Zero problems.

shell.execute 'echo  'QUIT' | curl -sS telnet://example.com:25'
result='220 example.com ESMTP Postfix 221 2.0.0 Bye'

Just now, I got this:

shell.execute 'echo  'QUIT' | curl -sS telnet://example.com:25'
result='No shell available'

I see two threads with this same error message, from 2 and 8 years ago:
Link1 Link2

And for the past 8 hours, it’s again working perfectly normally. How weird!

2

Add full path

3

I don’t see how that would help - it works over 99% of the time as it, and only fails in a very rare occasion.

I wonder, is the “No shell available” message a Xojo error string or the OS?

4

My guess would be the OS and on macOS it wouldn’t surprise me if this was a security feature misbehaving.

1 Like
5

Update: 15 days later (with the script running every 2 hours) e.g. 180 more invocations, and this error has not returned. This is running in a stand-alone webApp created with Xojo 2024R4.2, under a VM on macOS 14.6.1.

6

I am presuming you mean that 14.6.1 is the guest OS. It’s tricky to talk about something that “sometimes” fails (and now you indicate that it seems to be behaving again.) Still, on a desktop project, I resolved a shell problem (on Sequoia) by defining the shell backend as zsh. Below Catalina I use the default bash. And that seems to work on everything in between.