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Removing Header & Trailer from a file


 
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# 1  
Old 10-02-2009
Removing Header & Trailer from a file

Hi All,

I am karthik. I am new to this forum. I have one requirement.

I have a file with header and footer.

Header may be like

HDR0001
or
FILE20090110

(Assume it is unknown so far, but i am sure there is a header in the file)

likewise file has the trailer too.

I just want to remove the header & footer and BCP data into a table.

Note: The file size would be 1.5 GB to 2.0 GB.

So i am looking for some good way to remove the header and trailer.

Inputs are welcome!
# 2  
Old 10-02-2009
This should do the trick:

Code:
awk 'NR<3{s=$0;next}{print s;s=$0}' file > newfile

or:

Code:
sed '1d;$d' file > newfile

# 3  
Old 10-02-2009
Thanks Franklin!

I tested the second one. It works fine.

But i don't want to create another file. I tested the script as below

filename > filename. After executing the script, the <filename> becomes empty.

so isn't possible to remove the header & footer and store it in the same file itself?

Also can you tell me what is the difference between the first one and second one? i mean which will give give good performance?

Last edited by karthi_gana; 10-02-2009 at 02:30 PM..
# 4  
Old 10-02-2009
Code:
awk 'NR<3{s=$0;next}{print s;s=$0}' file > newfile

Explanation of awk code:

Code:
NR<3{s=$0;next}

If line number < 3 assign the current line to variable s and read the next line

Code:
{print s;s=$0}

Print the previous line and assign the current line to variable s

Explanation of sed code:

Code:
sed '1d;$d'

Delete the first (1d) and the last line ($d)
# 5  
Old 10-02-2009
Answer for one of your question:

How to make the edit in the same file itself,
use -i switch in sed as

Code:
sed -i <REQUIRED-PART>

# 6  
Old 10-07-2009
Quote:
Originally Posted by thegeek
Answer for one of your question:

How to make the edit in the same file itself,
use -i switch in sed as

Code:
sed -i <REQUIRED-PART>


sed: illegal option -- i
$

i got the above error message.

i am using ksh.

is there any other option to do this?
# 7  
Old 10-08-2009
Quote:
Originally Posted by karthi_gana
sed: illegal option -- i
$

i got the above error message.

i am using ksh.

is there any other option to do this?
No, but you can do something like:

Code:
sed '1d;$d' file > tempfile && mv tempfile file


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