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Insert line based on found string

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# 1  
Old 09-07-2016
Insert line based on found string
Hi All
I'm trying to insert a new line at the before each comment line in a file.
Comment lines start with '#-----'
there are other comments with in lines but I don't want a new line there.
Example file:
Code:
blah
blah #do not insert here
#this is a comment
blah #some more 
#another comment

the desired result would be
Code:
blah
blah #do not insert here

#this is a comment
blah #some more 

#another comment

I tried
Code:
tr '#' '\012'

and a number of variants using sed etc but I don't get the desired result.

grateful for any pointers . . .
# 2  
Old 09-07-2016
Hello Mudshark,

Could you please try following and let me know if this helps you.
Code:
awk '/^#/{print RS $0;next} 1'   Input_file

Output will be as follows.
Code:
blah
blah #do not insert here

#this is a comment
blah #some more 

#another comment

Thanks,
R. Singh
This User Gave Thanks to RavinderSingh13 For This Post:
Mudshark
# 3  
Old 09-07-2016
And in sed :
Code:
 sed '/^#/{x;p;x;}' input-file

These 2 Users Gave Thanks to greet_sed For This Post:
Mudshark Scrutinizer
# 4  
Old 09-07-2016
Many thanks all for the responses.
RavinderSingh13 - That worked ok although I had to use nawk on Solaris.
greet_sed - that also worked fine.
I also found another similar thread and used this ... ( where filename = 'x' and comment lines start with '#-')
Code:
nawk '{ gsub ("#-", "\n#-") }1' x

# 5  
Old 09-07-2016
Try also
Code:
sed 's/^#/\n#/' file

This User Gave Thanks to RudiC For This Post:
greet_sed
# 6  
Old 09-08-2016
Unix sed needs backslash-realnewline i.e. needs multi-line
Code:
sed 's/^#/\
#/' file

Or insert an empty line with
Code:
sed '/^#/i\
' file

# 7  
Old 09-08-2016
Code:
awk '/^#/{print x}1' file
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