Regular Expression Puzzle

[Ray Parrish]

Werner Schram wrote:
> Ray Parrish wrote:
>   
>> Alan McKay wrote:
>>   
>>     
>>> Dude, that's a bit of a convoluted way to go about it.
>>>
>>> How about keeping it simple?
>>>
>>> cat file | sed "s/<div>/<p>/g" | sed "s/<\/div>/<\/p>/g" > newfile
>>>   
>>>     
>>>       
>> Hello,
>>
>> I tried that command, and it does indeed change the <div>'s to <p>'s, 
>> but it does it across the entire file, and I do not want to replace 
>> every <div> in the file with paragraph tags.
>>
>> I need the ability to change certain blocks of text that are similar but 
>> different in different files, and I would like a command that handles 
>> all variations on the basic theme of it starts with a certain string, 
>> varies in the middle, then is the same on the end of the string again.
>>
>> Those sample lines iI provided are from the navigation links I put at 
>> the top of all of my web pages, and it would be nice to do a broadcast 
>> change to update, or change their appearance instead pf having to edit 
>> every single file by hand, which takes hours.
>>
>> Well, I'm back to reading up on regular exprssions to see if there is 
>> some possible way to make a broadcast change through all of my pages to 
>> change the appearance of the navigation links.
>>   
>>     
> Doing some reading is a good idea, regular expression can be extremely 
> usefull. And being able to write undecipherable code that actually does 
> what you want greatly boosts your l33t score :)
>
> In the mean time, I think this one is what you are looking for:
>
> sed "s,<div><a href=\"index.html\">Ray's Links 
> Home</a>\(.*\)</div>,<p><a href=\"index.html\">Ray's Links 
> Home</a>\1</p>,g" file
>
> the inportant part is the \(.*\) in the search pattern and the \1 in the 
> replace pattern. The brackets mean that you are grouping something to 
> which you can reference back from the replace pattern using \1. The . 
> matches any character and * means that you expect 0 or more of the 
> previous character.
>
> Werner
>   
When I get done with my email, I'm going to try that syntax you used 
there without sed to see if it works. If it will work that way, I can 
use it with my new block oriented, multi-document search and replace 
program I just finished writing in bash, with the help of Xdialog for 
some GUI support.

In it I assign a SearchTerm, and a ReplaceTerm variable which can 
contains lines of text, and use them in the bash replace expression like 
so -

FileContents=`cat file.html`
FileContents=${FileContents/$SearchTerm/$ReplaceTerm}

If I can just edit the SearchTerm, and ReplaceTerm to add the \(.*\) and 
the /1 in each respectively, and it works, then it will be a real boon 
to my ability to change my web sites around.

Later, Ray Parrish

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