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sed pattern to delete lines containing a pattern, except the first occurance

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# 1  
Old 06-23-2011
sed pattern to delete lines containing a pattern, except the first occurance
Hello sed gurus. I am using ksh on Sun and have a file created by concatenating several other files. All files contain header rows. I just need to keep the first occurrence and remove all other header rows.

Code:
header for file
1111
2222
3333
header for file
1111
2222
3333
header for file
1111
2222
3333

Should look like:
Code:
header for file
1111
2222
3333
1111
2222
3333
1111
2222
3333

I know how to remove lines matching a pattern, but I am brain-locking on the pattern needed to skip the first occurrence.

Removes lines starting with "header"
Code:
sed '/^header/d' filename

Thanks for any help!
Gary
# 2  
Old 06-23-2011
an awk one:

Code:
 
awk '/header/&&c++>0 {next} 1' input_file

This User Gave Thanks to panyam For This Post:
gary_w
# 3  
Old 06-23-2011
Code:
sed '1!{/^header/d;}' inputfile

or

Code:
sed '2,${/^header/d;}' inputfile

This User Gave Thanks to ctsgnb For This Post:
gary_w
# 4  
Old 06-23-2011
Code:
awk ' /^header/ && FNR > 1 {next} {print $0} ' infile > newfile

This User Gave Thanks to jim mcnamara For This Post:
gary_w
# 5  
Old 06-23-2011
Thanks ctsgnb I could net get that syntax for specifying the range to operate on.
Thanks to all for the different methods!
Gary
# 6  
Old 10-06-2011
Quote:
Originally Posted by panyam
an awk one:

Code:
 
awk '/header/&&c++>0 {next} 1' input_file

Is there a way to do this for multiple regex's? I have got part of it with sed:

Code:
sed '/pattern1/d;/pattern2/d;/pattern3/d;/pattern4/d' file > filetest

However, I didn't figure out how to skip the first instance of each pattern...

This one seems to double the data in the file...:

Code:
 awk '/pattern1/&&c++>0 {next} 1;/pattern2/&&c++>0 {next} 1' file > testfile

Smilie
Last edited by herot; 10-06-2011 at 03:23 PM..
# 7  
Old 10-06-2011
Quote:
Originally Posted by panyam
an awk one:

Code:
 
awk '/header/&&c++>0 {next} 1' input_file

awk '/header/&&c++ {next} 1'
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