Question

I have a text file with the following type of data in it below:

Example:
10212012115655_113L_-247R_247LRdiff_0;
10212012115657_114L_-246R_246LRdiff_0;
10212012115659_115L_-245R_245LRdiff_0;
10212012113951_319L_-41R_41LRdiff_2;
10212012115701_116L_-244R_244LRdiff_0;
10212012115703_117L_-243R_243LRdiff_0;
10212012115705_118L_-242R_242LRdiff_0;
10212012113947_317L_-43R_43LRdiff_0;
10212012114707_178L_-182R_182LRdiff_3;
10212012115027_278L_-82R_82LRdiff_1;

I would like to copy all the data lines that have

1) _2 _3 _1 at the end of it into another file along with
2) stripping out the semicolon at the end of it.

So at the end the data in the file will be

Example:  
10212012113951_319L_-41R_41LRdiff_2
10212012114707_178L_-182R_182LRdiff_3
10212012115027_278L_-82R_82LRdiff_1

How can I go about doing this?
I’m using linux ubuntu 10.04 64bit

Thanks

Answer 1

Here’s one way using sed:

sed -n 's/\(.*_[123]\);$/\1/p' file.txt > newfile.txt

Here’s one way using grep:

grep -oP '.*_(1|2|3)(?=;$)' file.txt > newfile.txt

Contents of newfile.txt:

10212012113951_319L_-41R_41LRdiff_2
10212012114707_178L_-182R_182LRdiff_3
10212012115027_278L_-82R_82LRdiff_1