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Unix help to find blank lines in a file and print numbers on that line

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Top Forums Shell Programming and Scripting Unix help to find blank lines in a file and print numbers on that line
# 8  
Old 10-10-2009
Quote:
Originally Posted by Lucky Ali
Hi,
I would like to know how to solve one of my problems using expert unix commands.

I have a file with occasional blank lines;
for example;

dertu
frthu
fghtu

frtty
frtgy
frgtui

frgtu
ghrye
frhutp
frjuf

I need to edit the file so that the file looks like this;
1
dertu
frthu
fghtu
2
frtty
frtgy
frgtui
3
frgtu
ghrye
frhutp
frjuf
************
That is: I want to grep or find the blank line and sequentially number the blank lines and print that number in the blank space.

Hope you guys understood what I wanted.

Please let me know the best way for doing this;

Lucky Ali
Hi!

Still :-) one way to skin the cat:
Code:
sed -n "/^$/ ="

pen
Last edited by pen; 10-10-2009 at 05:26 AM.. Reason: Edit: Silly me, those numbers were expected to be sequential. Sorry...
# 9  
Old 10-10-2009
Quote:
Originally Posted by pen
Code:
sed -n "/^$/ ="

Can you explain Smilie
# 10  
Old 10-12-2009
Quote:
Originally Posted by danmero
Can you explain Smilie
First of all, as mentioned in the "Edit" part of my last posting, my solution does not provide a proper answer to the original question - the requirement was to number sequentially (1,2,3...) the blank lines.

The mentioned sed command matches blank lines and replaces them with the current line number. Hence, the the following
Code:
a

b

c

will be printed out as
Code:
a
2
b
4
c

pen
# 11  
Old 10-16-2009
awk(1) one-liner
Code:
awk '{ print NF ? $0 : ++n }'
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