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!