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Get nth occurence of string from a file

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# 1  
Old 04-09-2015
Get nth occurence of string from a file
I have file in which the data looks like this,

Code:
01,0000000,xxxxxxx/                        
02,xxxxxxxx,yyyyyy/                                    
03,test1,41203016,,/      
01,0000000,xxxxxxx/                        
02,xxxxxxxx,yyyyyy/                                    
03,test2,41203017,,/     
01,0000000,xxxxxxx/                        
02,xxxxxxxx,yyyyyy/                                    
03,test3,41203018,,/

I would not know what values will be there in place of test1, test2 and test3 in my file.

I wrote a command to get these values from the file,
Code:
grep "^03,.*,.*$" file.dat | cut -d"," -f2

this returns,
Code:
test1
test2
test3

Is there a way I can get a specific occurence (ex: 5th or 9th) of this string. let say in this case, can I get only test2?

Appreciate your help.
# 2  
Old 04-09-2015
Assuming your code works correctly for your data:

Code:
recnum=4
grep "^03,.*,.*$" file.dat | cut -d"," -f2 |  awk -v r_num=$recnum 'NR==r_num'

The reason for my caveat is your regex - looks unusual, but could be just right for your dataset.
This User Gave Thanks to jim mcnamara For This Post:
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# 3  
Old 04-09-2015
Please use code tags for all code, data, and output.

awk is a powerful language for this sort of thing, you can match strings like grep, but you can also count the number of lines and columns, tell it how columns are separated, count things and use variables. You'll find it on any UNIX or UNIX-like system.

Code:
$ awk -F"," -v X="03" -v N=2 '($1 == X) && ((++L)>=(N+0)) { print $2 ; exit }' inputfile

test2

$

-F"," tells it to consider , as column splitters.

-v X="03" and -v N=2 preset the X and N variables inside awk. awk has its own variables independent of the shell's.

($1 == X) && ((++L) ==(N+0)) { ... } means "run the following code when the first column equals the variable X, and L is equal to N". $ means column in awk, not variable. $1 would be 01, $2 would be 0000000, etc. "++L" adds one to L every time ($1 == X) is true.

I did (N+0) to make sure awk used N as a number, not a string.

{ print $2 ; exit } means "print the second column, then stop reading this file".

So, a combined grep, wc, and cut.
This User Gave Thanks to Corona688 For This Post:
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# 4  
Old 04-10-2015
Thanks a lot for the command and a beautiful explanation.

---------- Post updated 04-10-15 at 02:34 PM ---------- Previous update was 04-09-15 at 02:53 PM ----------

I have an additional requirement for this,

I need to replace this value with some other value.
Is there a way I can do this by using a command in conjunction with this awk command.

Code:
$ awk -F"," -v X="03" -v N=2 '($1 == X) && ((++L)>=(N+0)) { print $2 ; exit }' inputfile

In this test2 should be replaced with replace2.

Please help.
# 5  
Old 04-10-2015
how about this?

Code:
{ $2="replace2"; print $2 ; exit }'

# 6  
Old 04-10-2015
Thanks for your reply.

I tried this..
Code:
awk -F"," -v X="03" -v N=6 '($1 == X) && ((++L)>=(N+0)) { $2="replace2"; print $2 ; exit }' myfile.txt > temp.txt

but this is replacing whole content of my file with replace2.
# 7  
Old 04-10-2015
Quote:
Originally Posted by r@v!7*7@
Thanks for your reply.

I tried this..
Code:
awk -F"," -v X="03" -v N=6 '($1 == X) && ((++L)>=(N+0)) { $2="replace2"; print $2 ; exit }' myfile.txt > temp.txt

but this is replacing whole content of my file with replace2.

care to give an example of what you are looking for? exact input and exact output samples would help.
This User Gave Thanks to senhia83 For This Post:
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