vi/comp.editors/sandr

From: dylan@ibmpcug.co.uk (Matthew Farwell)
Newsgroups: comp.editors
Subject: vi search and replace (LONG)
Keywords: vi replace
Date: 16 Sep 91 18:48:17 GMT
Reply-To: dylan@ibmpcug.CO.UK (Matthew Farwell)
Organization: The IBM PC User Group, UK.

In article <stanley.685027807@techunix.technion.ac.il> stanley@techunix.technion.ac.il (stan c) writes:
>can anyone tell me how to correctly use the replace 
>feature in vi?
>I have a (rather long) file which has a whole bunch of control
>characters at the end of each line (cat -v shows it as ^M)
>How can I get rid of them?

Ok, the quick answer is:

:1,$s/^M//g

where ^M is ctrl-V ctrl-M.

The replace command has a format like this:
:<range of lines>s/<old text>/<new text>/<qualifiers>

<range of lines> can be specified in a number of ways.  You can give the
numbers, ie 1,4 does lines 1 2 3 4 ($ is last line), you can say from
mark 'm' to mark 'n', ie 'm,'n, or you can give a search command, ie
/^$/,/^fredleg/ does from the next blank line to the next line matching
^fredleg.  Or you can have any combination of those.  You can even
search backwards using ? instead of / if you want to.

so:
:1,$		== every line
:/^$/,$		== lines from the first blank line to the end
:'m,/^$/	== lines from mark m to the first blank line after the
		   current cursor position
:1,?^$?		== line 1 to the previous blank line.

but be careful when using the searching commands when defining a range
of lines.  If you have wrapscan set it can sometimes have interesting
effects, if, say, you don't hit a match before the end of the file.  I
find that using searches that aren't certain to hit the right place is a
recipe for disaster.  I just prefer to go to the line, mark it and then
go back and use :'m,.  or whatever.

<old text> is just a normal regular expression [*]
<new text> is the replacement text. The simple form is:

:1,$s/dylan/matthew/
or
:1,$s/dyl*an/matthew/

You can also use the \L \l \U \u \E and \e qualifiers.  These convert
text to lower case or to upper case.  The lower case versions of these
only work on the next letter.  ie if you want to capitalize the 'd'
every occurence of the word 'dylan' in your text, then you can use

:1,$s/dylan/\u&/	(& means all matched text, in this case 'dylan')

If, however you want to capitalise the whole word, then you use \U. If
you want the entire matched string capitalised, then just using \U is
sufficient. If, however, you want to capitalise only parts of the
string, then you can use \e[**] to terminate the changes. ie

:1,$s/\(dyl\)\(an\)/\U\1\e\2/	(\1 and \2 are equivalent to whatever
				the first and second \( \) sequences
				matched, in this case \1 == 'dyl' and \2
				== 'an')

changes all occurences of dylan to DYLan.

Now, the above statements are not strictly true. By default, vi only
susbstitutes the first match on a line, so for instance only the first
dylan in the first line of my .sig would get changed. If you want to do
*all* occurences, then you must add a 'g' qualifier to the end, ie

:1,$s/dylan/matthew/g

The other qualifiers are 'c' and 'p'. 'c' asks for confirmation before
making the change. 'p' prints the matched strings after any replacement
has occured.

Hope this helps.

Dylan.

[*] I haven't got time right now to go into the depths of regular
expressions. Maybe some other time.
[**] As far as I can see, \e and \E have exactly the same effect and are
interchangeable. I'm willing to be corrected though.
-- 
dylan@ibmpcug.co.uk || ...!uunet!ukc!ibmpcug!dylan
C makes it easy for you to shoot yourself in the foot. C++ makes that
harder, but when you do, it blows away your whole leg - Bjarne Stroustrup