Mapping Function keys in vi

  UNIX allows us to map functional keys like F1, F2 to  some commands. .exrc file is used in order to make these mapping permanent.

   For example, say everytime we open a file, when we want to see the file contents with line numbers, we go to the escape mode and type :se nu.  Instead, we can have a short cut for this.

  Let us see how to map the key F3 to do set line number inside vi.

SunOs/Linux:
  In the Sun OS, this can be done by having the following entry in the .exrc file:

    map  #3 :se nu


HP-UX:
  In the HP machine, it is a bit different because the key codes are read differently.  Have the following entry in your .exrc file:

   map ^[[13~  :se nu

   Note: The above map pattern is actually typed as shown below:
    ^[[11~ = Ctrl-V + Esc + [ + 1 + 3 + ~


   Once this setting is done, open a file in vi, and press F3 and enter, you should see the line numbering done.

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