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Sed delete certain number of empty lines

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# 1  
Old 07-25-2011
Sed delete certain number of empty lines
Hi

What I'm trying to do is delete every blank line upto a certain number, so for instance I only want to delete the first 4 empty lines within a file, I know how to delete every line with:

Code:
sed '/^$/d'

But I can't figure out how to limit it to only the first 4 occourances

I though it would be:
Code:
sed '4,/^$/d'


But that doesn't seem to do it
# 2  
Old 07-25-2011
I don't think 'sed' can do it, but here is one possible solution:
Code:
#!/bin/ksh
typeset -i mCnt=0
for mLine in $(egrep -n '^$' b); do
  mTmp=$(echo ${mLine} | sed 's/:/d/')
  mOLine=${mOLine}${mTmp}';'
  mCnt=${mCnt}+1
  if [[ ${mCnt} -eq 4 ]]; then
    break
  fi
done
sed "${mOLine}" Input_File

# 3  
Old 07-25-2011
You can loop 4 times over sed
Code:
for i in 1 2 3 4
do
sed '/^$/d'
done

# 4  
Old 07-25-2011
Quote:
Originally Posted by h@foorsa.biz
You can loop 4 times over sed
Code:
for i in 1 2 3 4
do
sed '/^$/d'
done

Hi


that didn't work, it just goes in a loop 4 times removing all empty lines from the file.

I guess an example input -> output would be:

Input
Code:
1

2

3

4

5

6

Output:
Code:
1
2
3
4

5

6

# 5  
Old 07-26-2011
Hi,

Test this pure 'sed' solution:
Code:
$ cat infile
Sat Jul 23 16:10:03 EDT 2011



Jul 22 2011
Jul 23 2011

Jul 24 2011

Jul 25 2011

Jul 26 2011

Jul 27 2011
$ cat script.sed
/./ { p ; b }
x
s/\(\n\)/&/4 
t a
x
H
b
: a
x
p
$ sed -nf script.sed infile
Sat Jul 23 16:10:03 EDT 2011
Jul 22 2011
Jul 23 2011
Jul 24 2011

Jul 25 2011

Jul 26 2011

Jul 27 2011

Regards,
Birei
# 6  
Old 07-26-2011
Quote:
Originally Posted by duonut
so for instance I only want to delete the first 4 empty lines within a file
Code:
awk '!NF && c<4{c++;next}1' file

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