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reversing and appending data in multiple files


 
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# 1  
Old 08-26-2009
reversing and appending data in multiple files

Hello,

I have a some files that look like this:
Code:
0 3
1 5
2 8
3 7

I want to reverse and append the data so it looks like this:
Code:
3 7
2 8 
1 5
0 3
0 3
1 5
2 8
3 7

I first thought about using cat and tac cleverly with some redirection and pipe in a one-liner but I couldn't get it to work.

What I do now is the following:
Code:
for i in log* 
do awk '{ a[i++] = $0 } END { for (j=i-1; j>=0;) print a[j--]; for (j=0; j<=i-1;) print a[j++]}' $i > $i.new
mv $i.new $i
done

Actually I would like to do something like this:

tac log1 | cat >> log1

but the result of tac log1 is now at the end of log1 instead of at the beginning. Is it possible to use the second option somehow in a oneliner but with the result of tac log1 at the beginning of log1?

Thanks in advance

Last edited by vgersh99; 08-26-2009 at 01:33 PM.. Reason: code tags, PLEASE!
# 2  
Old 08-26-2009

Code:
{
 cat log1
 tac log1
} > temp && mv temp log1


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