UNIX for Dummies Questions & Answers

Again, very hypothetical since the OP did not specify this and the field names are well known so you only use the level of accuracy that is required. Why do you use g (which introduces inaccuracy) when you can just use 1 and 2 to change the field you want in the previous examples.

If you insist on using g to do a global replace and if you also have similarly named fields you just need to be more precise to make a distinction, then use e.g.

Code:

echo $line|sed 's/\b\(tcolor=\)[^|]*/\1blue/g'
Boston|tcolor=blue|desc=Large city in New England|url=www.boston.com|setcolor=green

Likewise you do not have to agree with me, but this regex is easy, not complex, and quickly crafted so I do not think it is accurate to talk about wasting time. And IMO it certainly is not as black and white as you put it. I appreciate the discussion though.

its easy to you and me, but not to a newbie.

..., who nonetheless managed:

Code:

I figured out: sed 's/tcolor=.*|/tcolor=blue|/'

and all I did was replace . with [^|] to make it non-greedy enough for this application.

yes , but he still hit a snag and had to figure out how to solve greediness. and that's why i suggest not using regex for such a task, where fields are clearly delimited by "|" and he can just go split the string on "|", go through them, check for "tcolor" and change it. there's no need to create regex (and on top of that, take care of greediness ) for that simple task. Sometimes, things can be done simple.

Well for that snag I offered a simple solution. Besides I could just as well say:

Code:

awk -F"|" '{for(i=1;i<=NF;i++){if($i~/^tcolor/){$i="tocolor=blue"}};print  }' OFS="|"

may be simple to you and me, but not to a newbie ( do I spot a tiny bit of regex in there BTW? )

maybe or maybe not, BUT that newbie should already know what are for loops, , if/else constructs, and since in this case, OP already know a bit of regex, he should be able to guess what is "~" as well.... combining all these bits and pieces, a newbie can roughly guess what its doing.

Code:

awk -F"|" '{ 
      for( i=1;i<=NF;i++} { 
          if( $i~/^tcolor/) { 
            $i="tocolor=blue"
          }
      };
       print  
}' OFS="|" file

anyway, we are going OT so have a gd weekend.

Yes OT and good weekend to you too but by your criterion I think then you should likewise use:

Code:

 $i~/^tcolor=/)

to make your regex non-greedy enough.