Linux for S/390 Hints and Tips

Certain Linux commands can pose unique problems when they are issued at a 3270 console. As an example, the ping command will continue indefinitely until it is cancelled. (However, this situation can be avoided by including a "count" option (the -c nn option) when the ping is issued.)

In an ASCII environment, most commands can be cancelled or otherwise interrupted through a keyboard-supplied Ctrl-key sequence (the keyboard "Ctrl" key is often illustrated in documentation using the carat ( ^) symbol). For the ping (and many other commands), the Ctrl-C (or, ^c) sequence provides the appropriate interrupt.

However, the ability to generate this type of interrupt is not commonplace (or may not be possible) when using most 3270 emulators. In cases where this is possible, a nonintuitive and often error-prone keyboard remapping is (or would be) required.

Still, it is possible to supply an alternative "interrupt" in a 3270-based Linux environment. This is accomplished by providing a two-character "command" at the console command line. The first of these characters must be an EBCDIC x'5F' (the logical negation (¬) symbol, which itself must often be mapped to a specific key by the emulator). The second character required is the same alphabetic character that is used, by convention, in an ASCII environment.

Thus, the comand necessary to stop a runaway ping on a 3270 console is:

   ¬c