OpenExtensions for z/VM "Q"s and "A"s

Question: How do I change the control sequence prefix character in the shell?

Answer: First, let's describe just what the "control sequence prefix character" is.

The OpenExtensions for z/VM Shell and Utilities uses the United States cent sign (¢) as the control sequence prefix or, as it is referred to in the OpenExtensions for z/VM manuals, the escape character. This is the character with which you prefix a control character to perform the function of the control character. For example, "¢C" performs the same function in OpenExtensions for z/VM that "Ctrl-C" performs on a UNIX system.

The problem here is that the U.S. cent sign is not a portable character in non-U.S. terminal code pages. This is a special problem with the advent of the Euro currency symbol. Also, the OpenExtensions for z/VM Shell and Utilities hardcoded the U.S. cent sign as the control sequence prefix.

You can use the -pfx option of the stty command to change the control sequence character.

This option of the Shell and Utilities command, stty, allows you to change the control sequence prefix. The syntax of the option is

    stty -pfx |char|

where |char| is any character of the user's choice. The stty command with this option may be specified on a user by user basis or it can placed in the /etc/profile Shell and Utilities system profile to change the control character sequence for all users of the OpenExtensions for z/VM Shell and Utilities.

There is also a "reset control sequence prefix" option that changes the value back to the default U.S. cent sign. To reset the control sequence prefix issue

   stty -rpfx

If APAR VM62080 is not installed on the Shell and Utilities, there is a CMS Callable Service routine that allows you to change the shell's escape-character. Place the following exec on a common "tools" disk on your VM system

      -------------------clip here-----------------------
        /*  SETESC EXEC - Set the 'EscChar' prefix  */
        Parse Arg inprefix .
        If inprefix = '' Then inprefix = '¢'
        Address OpenVM 'BPX1TSX inprefix'
        Exit
      -------------------clip here-----------------------

Then in the file /etc/profile you add the command

        cms 'EXEC SETESC c'

where "c" is the new character you want the escape character to be.

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