Re: some vi equivalents please?

[Giorgos Keramidas <keramida@ceid.upatras.gr>]

On Fri, 31 Oct 2008 08:08:42 -0700 (PDT), rustom <rustompmody@gmail.com> wrote:
> 1. In vi I can delete a line that contains a <pat> with
> :g/<pat>/d
>
> How is this done in emacs?

I commonly use a keyboard macro for this sort of thing.

Type `C-x (' to start defining a macro, the run ``one iteration'' of a
complex set of commands, like `C-s pat C-a C-k C-k', and finally finish
the macro by typing `C-x )'.  If the macro seems to work fine, it is
then easy to repeat it a specific number of times (C-u 100 C-x e) or
keep repeating the same macro by `C-x e e e e e e e ...'.

Macros are really powerful in Emacs.  I have used them to convert text
files from one `ChangeLog' format to another, or to reformat a bit parts
of a text file that contain dates, and so on.  The manual describes a
lot of even more interesting things you can do with keyboard macros.
Have a look at it by typing `C-h r m "Keyboard Macros" RET'.

> 2. match-variables:
> If I want to remove everything after the second : (in a file that has
> 3 fields separated with two :'s)
> I do
> :s/\(.*\):\(.*\):.*/\1 \2
> How do I do that in emacs?

Select a region (or the entire buffer with `C-x -h') and then type:

    M-x replace-regexp RET \(.*\):\(.*\):.* RET \1 \2 RET

You can even get an interactive replace mode by typing:

    M-x query-replace-regexp RET \(.*\):\(.*\):.* RET \1 \2 RET

Emacs is a bit more verbose when replacing regular expressions, but the
extra verbosity is a bit nice to see in the default case.  Binding one
of these to a `shortcut' like `C-c R' is very easy

    (global-set-key (kbd "C-c R") 'query-replace-regexp)
    (global-set-key (kbd "<f4>") 'query-replace-regexp)

and you *still* get to see the verbose, helpful name of the command,
with the full feature set of command-completion when you need it.