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Switch first 10 rows in a file with the last 10 rows using shell script

Posted on 2011-03-01
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353 Views
Last Modified: 2012-06-27
If I have a file called file1.txt and it looks like this

/path/file1.txt
7.363E+07
7.363E+07
7.363E+07
7.363E+07
7.363E+07
7.363E+07
7.363E+07
7.363E+07
1.473E+08
6.627E+09
4.607E+07
4.607E+07
4.607E+07
4.607E+07
4.607E+07
4.607E+07
4.607E+07
4.607E+07
9.215E+07
4.147E+09

I want it to look like this

/path/file1.txt
4.607E+07
4.607E+07
4.607E+07
4.607E+07
4.607E+07
4.607E+07
4.607E+07
4.607E+07
9.215E+07
4.147E+09
7.363E+07
7.363E+07
7.363E+07
7.363E+07
7.363E+07
7.363E+07
7.363E+07
7.363E+07
1.473E+08
6.627E+09
0
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Question by:libertyforall2
5 Comments
 
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Expert Comment

by:pwust
ID: 35012470
Do I get you right that the input file also can hold more than 20 lines, and you still want to swap first ten with last ten lines?
0
 
LVL 58

Accepted Solution

by:
amit_g earned 250 total points
ID: 35012613

tail -10 /path/file1.txt > /tmp/$$.$$ && head -10 /path/file1.txt >> /tmp/$$.$$ && mv /tmp/$$.$$ /path/file1.txt

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0
 
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Assisted Solution

by:pwust
pwust earned 250 total points
ID: 35012678
or, without tempfile, and taking into account files of more than 20 lines:
tail -n10 /path/file1;head -n$((`wc -l /path/file1|cut -d" " -f1`-10)) /path/file1 |tail -n$((`wc -l /path/file1|cut -d" " -f1`-20));head -n10 /path/file1

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Author Closing Comment

by:libertyforall2
ID: 35013031
Works great!
0
 
LVL 12

Expert Comment

by:tel2
ID: 35020995
Am I too late for the scripting party?

Here's a slightly more concise version:
(tail -10 /path/file1.txt;head -10 /path/file1.txt) > /tmp/$$.$$ && mv /tmp/$$.$$ /path/file1.txt

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