Java™ Application Development on Linux - Dator

44Chapter 2An Embarrassment of Riches: EditorsTable 2.2 Some useful vi substitutionsCommand:1,$s/ *$//:1,$s/^.*$/""/:1,$s/^"//:1,$s/"$//ExplanationRemoves all (any number of) trailing blanks—that is, looks for zero ormore blanks followed immediately by the end of line, and replacesthem with nothing (no characters between the last two slashes).Puts quotes around the text of each and every line.Removes the leading quote from any line that starts with one.Removes the trailing quote from any line that ends with one.There is so much more that could be said about regular expressions. Theyare one of the most powerful features for making big changes with fewkeystrokes. It’s an integral part of sed, Perl, and other tools. It’s in such demandthat it has been added to Java for better pattern matching. See Section 2.6 forways to learn more about regular expressions.2.2.4 Starting Off Right: .exrcYou can preset certain behaviors in vi by putting ex commands in a file called.exrc in your home directory. Those commands will be read whenever youinvoke vi and before you begin typing commands.Here’s a simple but useful .exrc example:" set my favorite options:set autoindent shiftwidth=4set ignorecaseAs you can see from the example, settings can be combined on one line.Note also that these lines do not begin with a colon. A colon is needed if youtype these lines from within vi—because you need to get into ex mode; butsince these are assumed to be ex commands (hence the name .exrc) they aregoing straight to the ex side of vi and no colon is needed. Comment linesbegin with a double quote; the rest of the line is ignored, and doesn’t need amatching quote.The ignorecase command tells vi to ignore any difference betweenupper- and lowercase characters when searching for text with the / or ? commands.The single character searches on the current line (f and F) are not