Substraction of matching lines from a file.

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# 1  
Old 08-26-2013
Wrench Substraction of matching lines from a file.

I have 2 files:
file1.txt contains


file2.txt contains


I need out put file1.txt as (without creating a new file).


file1.txt should contain the lines after the subtraction of lines in file2.txt, It will be very helpful for me, if you have a solution for this.

Last edited by Scrutinizer; 08-26-2013 at 04:55 AM.. Reason: code tags
# 2  
Old 08-26-2013
grep -vf file2 file1

To put the changes in the original file, create a new file and if the result is OK replace the original with the new file..
This User Gave Thanks to Scrutinizer For This Post:
# 3  
Old 08-27-2013
But this doesn't meets my requirement.
In my case the file1.txt file should be the out put after the subtraction of the lines as (file1.txt-file2.txt=file1.txt).
# 4  
Old 08-27-2013
You can probably do this if it is okay to create another file and then move it to original file

grep -vf file2 file1 >file3
mv file3 file1

This User Gave Thanks to krishmaths For This Post:
# 5  
Old 08-27-2013
But my intention is with out creating a new file like file3.txt.
# 6  
Old 08-27-2013
You could copy the input file first and use copy as input and create the original file as output..

Last edited by Scrutinizer; 08-27-2013 at 03:51 AM..
# 7  
Old 08-27-2013
also, try something like:
awk 'NR==FNR {a[$0]=$0; next; } {s=$0; sub("[^/]*$","", s); if (!a[s]) print}' file2.txt file1.txt |&
while read -p x ; do echo "$x" ; done > file1.txt

Last edited by rdrtx1; 08-27-2013 at 05:34 PM.. Reason: ksh example
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