finding the nth match


 
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# 1  
Old 06-15-2011
finding the nth match

I have a file that has information for a person....each person gets 3 or more lines to describe them.

I was hoping to match person 1, then person 2.....BUT I do not know how to tell grep I only want the first (2nd, 3rd or nth) match.

The alternative is doing line by line logic, which is fine with me as long as I know that is what I am supposed to be doing.

OS: Solaris 10

help?

thanks,

cs

Last edited by countryStyle; 06-15-2011 at 12:59 PM.. Reason: forgot to include unix type
# 2  
Old 06-15-2011
If you post your input file and sample expected output that would be more helpful.
# 3  
Old 06-15-2011
Quote:
Originally Posted by getmmg
If you post your input file and sample expected output that would be more helpful.
not really...but here it goes.
Make up any scenario you want....how about where each line starts with a single digit.

1
5
9
7
5

I want grep to get the the nth match of a digit matched via regex
using solaris
# 4  
Old 06-15-2011
Quote:
Originally Posted by countryStyle
not really...but here it goes.
Make up any scenario you want....how about where each line starts with a single digit.
Make up the scenario? Is this an actual problem or are you just quizzing us?

We often get questions about getting grep to cross multiple lines, but grep doesn't. But a 1-liner in awk might be able to do it.

We can't help you until we know how your data's organized because the logic depends on that. It's not psychic and neither are we.
This User Gave Thanks to Corona688 For This Post:
# 5  
Old 06-15-2011
Quote:
Originally Posted by Corona688
Make up the scenario? Is this an actual problem or are you just quizzing us?

We often get questions about getting grep to cross multiple lines, but grep doesn't. But a 1-liner in awk might be able to do it.

We can't help you until we know how your data's organized because the logic depends on that. It's not psychic and neither are we.
Yeah....I am a wanna be teacher and fulfill my fantasies by quizzing people on the internet. Go get a life....you are being difficult.

Maybe you answered my question....but you sound generally uninformed because you are being difficult: grep will not provide the nth match only.

can anyone else confirm?
# 6  
Old 06-15-2011
Quote:
Originally Posted by countryStyle
Yeah....I am a wanna be teacher and fulfill my fantasies by quizzing people on the internet. Go get a life....you are being difficult.
If you'd posted your data you could have had an answer an hour ago...
Quote:
Maybe you answered my question....but you sound generally uninformed
I'll ignore the personal slur and explain a little more.

grep considers no logic but patterns when matching lines. It doesn't remember anything about previous lines and has no expression to carry information from previous lines across to next ones. The awk language is much better suited, since it deals with lines/patterns and has variables plus logical expressions. (I think sed does too in a fashion, but its expression syntax is rather convoluted. awk gives you straightforward variables with names, and straightforward expressions with if/else.)
Quote:
because you are being difficult:
I'm only asking you for your data. I'm not even the first one.

If you really want I'll give you a ridiculous solution like grep pattern file | tail -n +5 | head -n 1 to get match 4 which is of course a very silly solution and might not work in Solaris. A less silly solution would be nawk '/pattern/ {} NR==2' but you asked for grep, this may not suit your needs, and there may be even more efficient ways to deal with the data depending on what it actually is and what you're trying to do.

Last edited by Corona688; 06-15-2011 at 01:57 PM..
# 7  
Old 06-15-2011
Quote:
Originally Posted by Corona688
If you'd posted your data you could have had an answer an hour ago... I'll ignore the personal slur and explain a little more.

grep considers no logic but patterns when matching lines. It doesn't remember anything about previous lines and has no expression to carry information from previous lines across to next ones. The awk language is much better suited, since it deals with lines/patterns and has variables plus logical expressions. (I think sed does too in a fashion, but its expression syntax is rather convoluted. awk gives you straightforward variables with names, and straightforward expressions with if/else.) I'm only asking you for your data. I'm not even the first one.

If you really want I'll give you a ridiculous solution like grep pattern file | tail -n +5 | head -n 1 to get match 4 which is of course a very silly solution and might not work in Solaris. A less silly solution would be nawk '/pattern/ {} NR=2' but you asked for grep, this may not suit your needs, and there may be even more efficient ways to deal with the data depending on what it actually is and what you're trying to do.
You slur...I slur back....that is how that first part went......anyways...

See....you did not need data to answer and there was no problem adding on the excellent commentary/lead about awk. I know a lot of people often ask for the answer to their specific issue and want YOU the other poster to do all the work for them (sometimes very practical). I am still at the general question looking to get more of a clue phase but if you want to do all my work for me let me know...I am certain you can do it fast.

I have something to work with and can make some progress (fingers crossed).

Thank you so much: )

---------- Post updated at 12:09 PM ---------- Previous update was at 12:03 PM ----------

had to change the line for Solaris:

grep pattern file | tail +5 | head -1

I am not working with large files here and performance is not an issue......

The line is easy to use and works in the Bash shell so....why is this a silly solution, performance, crossplatform issues?

thanks again.
 
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