topic Re: Capturing Ctrl + C in Operating System - HP-UX

Capturing Ctrl + C

Radhe Webster — Fri, 29 Jul 2005 08:48:56 GMT

I have created a script that is called out of a users .profile when they log in. In the script I have:

trap 'print "ENTER INFORMATION REQUESTED!"' INT
trap 'print "ENTER INFORMATION REQUESTED!"' QUIT

And then goes on to ask them for some requested information. For some reason it's not working correctly and ctrl + c breaks out of it. I've tried it with trap "" 1 2 3 and that isn't working either.

Any thoughts? Thanks

Re: Capturing Ctrl + C

Steve Steel — Fri, 29 Jul 2005 08:56:58 GMT

Hi

Use stty to change the intr value at the start and end of script . see stty -a

Why the trap.How is the script used

see
www.shelldorado.com for good shell tips

Steve Steel

Re: Capturing Ctrl + C

Simon Hargrave — Fri, 29 Jul 2005 08:57:09 GMT

The way trap works is, it EITHER ignores the signal (if you use a null argument) OR it runs the command then processes the trap.

eg

trap '' INT

will make it ignore Ctrl-C

trap 'echo test' INT

will make it print the word "test", then exit the program.

You can't have both unfortunately.

Re: Capturing Ctrl + C

Radhe Webster — Fri, 29 Jul 2005 09:01:33 GMT

It's so that our various vendors identify themselves (and we get emailed) when they log onto the system.

The command trap " INT generates syntax errors... should it not be trap "" INT

Re: Capturing Ctrl + C

Simon Hargrave — Fri, 29 Jul 2005 09:10:42 GMT

I was using 2 single-quotes. I guess you read this as one double-quote? You can use either a pair of single-quotes or a pair of double-quotes, it doesn't make a difference when using a null string. When specifying a command your use depends on whether you want shell expansion.

Re: Capturing Ctrl + C

Radhe Webster — Fri, 29 Jul 2005 09:13:27 GMT

I've gotten it to work by using stty to change the interrupt value, but trapping it is still not working.

Re: Capturing Ctrl + C

Stuart Browne — Fri, 29 Jul 2005 18:38:14 GMT

What shell are you using?

And does it fail when you just use:

trap 'print blah' 2