Compare 2 files and remove duplicate lines

[Anand_30]

HI,

I have 2 files a & b. I need to compare these 2 files and remove all the entry from file b which is same as that of file a.

Can anyone please help me do this.

Thanks
Anand

[Sundar_7 · Accepted solution]

grep -vf a b > c
mv c b

[Hein van den Heuvel]

Are those files sorted?
If they are, simply use: comm -2 a b > c
If they are not you may consider pre-sorting.

Hein.

[Muthukumar_5]

we can do this with diff command too as,

echo "`diff -u file1 file2 | grep -v '^++' | grep '^+'| sed -e 's/^+//'` > file2


We can use commands donot use temporary files then, we can use echo and redirection there.

sundar reply can be done as,

echo "`grep -vf file1 file2`" > file2

No temporary files there.