Question

I am running a C program using putty (don’t ask why) and it is working fine, except when I run a particular function, the string “PuTTy” appears at the end. This doesn’t seem to be affecting anything much, but I am just curious if anyone knows why this is happening and what sort of error this might indicate.

Note: When I run the code in a Linux terminal, there is no error whatsoever.

Answer 1

This is an issue with PuTTY caused by your program emitting the Control-E character. From the PuTTY FAQ:

A.7.12 When I cat a binary file, I get ‘PuTTYPuTTYPuTTY’ on my command
line.

Don’t do that, then.

This is designed behaviour; when PuTTY receives the character
Control-E from the remote server, it interprets it as a request to
identify itself, and so it sends back the string ‘PuTTY’ as if that
string had been entered at the keyboard. Control-E should only be sent
by programs that are prepared to deal with the response. Writing a
binary file to your terminal is likely to output many Control-E
characters, and cause this behaviour. Don’t do it. It’s a bad plan.

To mitigate the effects, you could configure the answerback string to
be empty (see section 4.3.7); but writing binary files to your
terminal is likely to cause various other unpleasant behaviour, so
this is only a small remedy.

Is your function outputting binary characters such as Control-E?