Thursday, January 24, 2008

Vim tips again, about ^M.

If you work in a mixed environment you will often open files that have ^M's in them. An example would be this:

------------------------------------------------------------------
import java.util.Hashtable; ^M
import java.util.Properties; ^Mimport java.io.IOException;
import org.xml.sax.AttributeList; ^M
import org.xml.sax.HandlerBase; ^Mimport org.xml.sax.SAXException;

/**^M
* XMLHandler: This class parses the elements contained^M
* within a XML message and builds a Hashtable^M

[snip]
------------------------------------------------------------------

Notice that some programs are not consistent in the way they insert the line breaks so you end up with some lines that have both a carrage return and a ^M and some lines that have a ^M and no carrage return (and so blend into one). There are two steps to clean this up.

1. replace all extraneous ^M:

:%s/^M$//g

BE SURE YOU MAKE the ^M USING "CTRL-V CTRL-M" NOT BY TYPING "CARROT M"! This expression will replace all the ^M's that have carriage returns after them with nothing. (The dollar ties the search to the end of a line)

2. replace all ^M's that need to have carriage returns:

:%s/^M/ /g

Once again: BE SURE YOU MAKE the ^M USING "CTRL-V CTRL-M" NOT BY TYPING "CARROT M"! This expression will replace all the ^M's that didn't have carriage returns after them with a carriage return.

Voila! Clean file. Map this to something if you do it frequently.

:help ffs - for more info on file formats


For more details, check this.

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