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regex to delete multiple blank lines in a file?

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# 1  
Old 10-11-2007
regex to delete multiple blank lines in a file?
can't figure out a way to delete multiple empty lines but keep single empty lines in a file, file is like this
#cat file
1

2

3



4

5
6
-

What I want is
1

2

3

4

5
6
--

any idea?
# 2  
Old 10-11-2007
Code:
sed '/^$/d;G' myFile

# 3  
Old 10-11-2007
thanks for the answer, but by doing this, you also ADD a empty line between
5 and 6, which before has no empty line between.

5
6

not
5

6



Quote:
Originally Posted by vgersh99
Code:
sed '/^$/d;G' myFile

# 4  
Old 10-11-2007
Code:
awk 1 RS= ORS="\n\n" filename

Use nawk or /usr/xpg4/bin/awk on Solaris.
# 5  
Old 10-11-2007
Tjhis is awesome!

Can you explain a little bit what the argument "1" does here?

Quote:
Originally Posted by radoulov
Code:
awk 1 RS= ORS="\n\n" filename

Use nawk or /usr/xpg4/bin/awk on Solaris.
# 6  
Old 10-11-2007
Sure:

everything <>0 in awk is true (you can use whatever you want: 1,2 ... 42 ...), true means use default action, which is print the current record.

You could use this, if you prefer:

Code:
awk -- -42 RS= ORS="\n\n" filename

# 7  
Old 10-11-2007
Thanks again! SmilieSmilieSmilieSmilie

Quote:
Originally Posted by radoulov
Sure:

everything <>0 in awk is true (you can use whatever you want: 1,2 ... 42 ...), true means use default action, which is print the current record.

You could use this, if you prefer:

Code:
awk -- -42 RS= ORS="\n\n" filename

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