I'm trying to write a bash shell script, that opens a certain file CATALOG.dat
, containing the following lines, made of both characters and numbers:
event_0133_pk.gz
event_0291_pk.gz
event_0298_pk.gz
event_0356_pk.gz
event_0501_pk.gz
What I wanna do is print the numbers (only the numbers) inside a new file NUMBERS.dat
, using something like > ./NUMBERS.dat
, to get:
0133
0291
0298
0356
0501
My problem is: how do I extract the numbers from the text lines? Is there something to make the script read just the number as a variable, like event_0%d_pk.gz
in C/C++?