Extracting number from text files for variable

Question

Hello again,
I have several different types of text files all with the line
# NPTS=32768  DT=0.005
somewhere in the file.  The numerical values are different for each file and I need to pull them out to assign as a variable for a program I am running.
How can I search a file and pull out each of these two numbers?
Thank you

Answer 1

Procyon's sed script assumes that the NPTS number and the DT number will both always have a period in them. In the original, the NPTS number doesn't have a period, and I don't know whether the DT number may lack a period.
You could try this instead (replacing the 's~....~p' part of Procyon's script):
's~# NPTS=\([0-9.]*\) *DT=\([0-9.]*\)~\1,\2~p'
That may let in stuff you want to exclude, for instance, it would let in:
NPTS=0.0.0.0.0 DT=1.1.1.1.1
and:
NPTS=....... DT=
and so on. But it's a tradeoff: if you know your data doesn't include anything like that, you can go with a simpler sed script. If you need to be fussier about what you're matching, then your sed script will need to be more complex.
EDIT: What I said in first paragraph is wrong. I overlooked the '*' after the '\.' in Procyon's script. What he's got will permit but not require a period. My final point still applies, though, to both of our suggestions. His script and my script would both match the second of my bad cases.
Last edited by Profjim (2008-09-17 21:31:34)