How to Create a Custom x3270 Keymap
It Might Already be Defined
First, you might want to make sure that the action you want isn't already
defined in the default keymap. The default keymap, documented on the x3270
manual page, defines common actions using the Meta key. For
example, the Reset action, which unlocks the keyboard, is defined
as Meta-R.
You Might Just Need the Alt Keymap
If your keyboard does not have a Meta key, it probably has an Alt
key. For such keyboards, there is an alternate version of the default keymap,
called alt; it defines the same actions using the Alt key
instead. You can also specify the alt keymap at start-up
with the command:
x3270 -keymap alt
You can also select the alt keymap at runtime with the Options->Change
Keymap... menu option; type alt in the pop-up window.
Defining a Simple Keymap in .x3270pro
If the action you want isn't defined in the default keymap or the alt
keymap, then you need to create a custom keymap. The easiest way
to do this is as follows. Using your favorite editor, create a file called
.x3270pro
in your home directory. In that file, put the following:
! Use the 'mine' keymap, defined below
x3270.keymap: mine
! Definition of the 'mine' keymap
x3270.keymap.mine: #override \
<Key>Prior: PF(7)\n\
<Key>Next: PF(8)
The first entry (x3270.keymap) tells x3270 to use the keymap
named mine. The second entry (x3270.keymap.mine)
is the definition of the mine keymap itself.
Now, run x3270, and do not specify a -keymap option.
The Page Up key will now emulate the 3270 PF7 key, and the
Page
Down key will emulate the 3270 PF8 key. (If you do not
have a Page Up or Page Down key, or if these keys do not
generate the X11 Prior and Next keysyms, this will not
work, but for most PC-based systems, it will.)
Rules for Keymap Definitions
You may now edit the keymap to create your own custom definition. The full
set of rules for keymaps (which are actually X11 Translation Tables)
takes a couple of chapters in a book -- I would suggest two O'Reilly's
books (Volume 4M: X Toolkit
Intrinsics Programming Manual, and Volume
5: X Toolkit Intrinsics Reference Manual) -- but here are the basics:
-
The first line is always:
x3270.keymap.name: #override \
where name is replaced by the name of the keymap you want to define.
(Note the backslash, which must be the last character on the line).
The body (middle) lines always have the format:
modifier <Key> keysym : Action(args)\n\
where:
modifier is an optional keyboard modifier such as Shift
or Ctrl
keysym is an X11 keysym: a symbolic name for a key, such as
semicolon
(the ';' key) or BackSpace (the Backspace key)
Action is an x3270 action such as Enter or PF
args are the optional action arguments, such as a number to
specify which PF key to transmit.
Note that each body line must end with the three characters '\n\'.
The last line is the same as the body lines, but must not have the
'\n\' at the end:
modifier <Key> keysym : Action(args)
More-specific definitions must come before less-specific definitions.
For example, the definition for Shift<Key>Backspace must come
before the definition for <Key>BackSpace (which also 'matches'
the BackSpace key with the Shift key pressed).
How to Find the Keysyms
To find out which keysym is being generated for any given key on your keyboard,
start x3270, but do not connect to a host. Then select the
File->Trace
Keyboard and Mouse Events menu option, and press the
No File
button on the pop-up.
An xterm window will appear. In that window, several lines
of text will appear for each key you press. Each entry will begin
with the text for the left-hand side of a keymap entry that will match
the key you pressed. You can cut and paste the text into your keymap
definition.
How to Find the Actions
These are documented on the x3270
manual page.
How to Debug Your Keymap
There are two x3270 options to aid with keymap debugging.
The File->Trace Keyboard and Mouse Events menu option pops up an
xterm
window which traces each keyboard and mouse event that x3270 processes.
The information traced includes the keymap (and line within the keymap)
that matched the event, the x3270 action that was run in response,
and if for some reason the action did not work, why it did not work.
The Options->Display Current Keymap menu option pops up a window
which displays the current keymap. This pop-up tells you exactly which
keymap entries are active, and can be sorted by keymap name, event, or
action name. Often times it will point out that x3270 isn't
using the keymap you thought it was, or that some of your keymap entries
are interfering with one another (such as the more-specific rule described
above).
Note that one of the commonest problems in configuring x3270
is figuring out where resources are being defined. Keymaps are defined
using resources, so this problem can complicate keymap definitions.
X11 resources can be defined in a number of different places:
-
In your X server, by reading them in with the xrdb command
-
In the file .Xdefaults in your home directory
-
In the file .Xdefaults-hostname in your home directory
-
In the file /usr/X11R6/lib/X11/app-defaults/X3270 (this is disabled
by default, but x3270 can be built to consult this file)
-
In the definitions compiled into x3270 from the file X3270.xad
-
In the file .x3270pro in your home directory
Note that of the above list, .x3270pro is guaranteed to be consulted
last, and its definitions override anything that appears in any of the
other places. This is why the example in this document uses .x3270pro.