Help with uniq -D [prepend]

Shell Programming and Scripting
1

Hi,
I am trying to add a blank line between sets of replicate values. I have been trying to use

 
uniq -D [prepend] -f4 input.txt > output.txt

The input is like

 
V2-1.0               -1.0  5500.00    4162.00  529976.06030125.0      1997A
V2-1.0               -1.0  6000.00    4285.00  529976.06030125.0      1997A
V2-1.0               -1.0      0.00    1479.00  529776.06030124.0      1997A
V2-1.0               -1.0    60.00    1489.00  529776.06030124.0      1997A

I am hoping for

 
 
V2-1.0               -1.0  5500.00    4162.00  529976.06030125.0      1997A
V2-1.0               -1.0  6000.00    4285.00  529976.06030125.0      1997A
 
V2-1.0               -1.0      0.00    1479.00  529776.06030124.0      1997A
V2-1.0               -1.0    60.00    1489.00  529776.06030124.0      1997A

Man pages suggests either separate or prepend should do the job however I cannot manipulate either to work.

Thanks in advance
Ryan

2

try this :

 uniq -f4 --all-repeated=prepend  yourfile

---------- Post updated at 01:54 PM ---------- Previous update was at 01:51 PM ----------

alternative solution :

awk '{if($5 != prev){print "\n"; prev = $5}}1' yourfile
3

Thanks Thanhdat!,
The uniq command worked a treat however the AWK prints a 5 line gap between replicate sets. Ive played about with it but cannot reduce this. I am using gawk, would this make a difference?

Is there any way of adding say a string with a count in each blank line i.e line1, line2,line3 etc?

Thanks again
Ryan

4

Something like that ?

awk 'NR==1{print "line"++c}NR>1 && $5 != prev{print "line"++c}{prev = $5}1' file
5

Thanks Danmero! I didnt understand how c worked until now.

6

c is the count variable, it's increased if the current line differ from the previous.
Test the command and u'll see.
Regards.

7

If that's what you want here is the shorter version.

awk 'NR==1 || $5!=prev{print "line"++c}{prev = $5}1' file