UNIX for Dummies Questions & Answers

Hi guys

I need help in comparing 2 files

for example

file1:

asdf|gdddd|acx
asdf|vcxzz|eww
avxc|bvvce|qwe

file2:
qwer|asdfg|sss
avxc|bvvce|eww
aass|weews|llk

I need to get the lines that are present in file1 but not found in file2.

so in these case
file3 will contain the lines which are present in file1 but not in file2

file3:
asdf|gdddd|acx
avxc|bvvce|qwe

I tried using sdiff but i cant understand the results.

Help me please.

if your files are sorted, look into 'man comm'.

Otherwise:

Code:

nawk 'NR==FNR {a[$0];next} !($0 in a)' file2 file1

Most (all ?) commands to find unique or common lines want the files sorted.

Code:

> sort file101 >file101.s
> sort file102 >file102.s

Then, I display the files to show them in sorted order. Done only to see, not needed as part of a 'solution'.

Code:

> cat file101.s
asdf|gdddd|acx
asdf|vcxzz|eww
avxc|bvvce|qwe
> cat file102.s
aass|weews|llk
avxc|bvvce|eww
qwer|asdfg|sss

The comm command can show what is in common, or what exists in only one of the files - review the manpages for more info

Code:

> comm -23 file101.s file102.s
asdf|gdddd|acx
asdf|vcxzz|eww
avxc|bvvce|qwe

Unlike your example output, all lines are unique to file101, thus all print. Review the third part of you lines and you will notice the differences. However, this should demonstrate the method to solve your problem.

sorry bout the wrong inputs
The files that i am really going to compare consists of 7000+ lines i think they are already sorted
for my sample:
file1:

asdf|gdddd|acx
asdf|vcxzz|eww
avxc|bvvce|qwe

file2:
qwer|asdfg|sss
avxc|bvvce|qwe
aass|weews|llk

output file:
asdf|gdddd|acx
avxc|bvvce|qwe

Code:

> sort file101 >file101.s
> sort file102 >file102.s

> comm -23 file101.s file102.s
asdf|gdddd|acx
asdf|vcxzz|eww

So, two entries are unique to the first file, although they are not the sample lines you show.

ok thanks

i tried using sdiff ang use grep to search for the lines with '<' which means unique to the first file then i tried using comm command which is simplier how come the results differ? which is more accurate? When i use sdiff it produces 3569 lines while it only produces 3540 lines when i use comm -23 command.