io » filter(source,target,matchPattern)
Description
This command filters out all the lines found in source via the specified matchPattern (regular expression) and
stores the matched lines in target. This can be advantageous for situation where a fairly large file contains the
content of interest but only in small portion. Instead of scanning through such large file with return of deriving
at a relatively fewer lines of interest (which takes time and compute resource), using this command could drastically
cut down the processing time. As a side effect, this command will produce a file - i.e. target - which contains
only the lines of interest. See the Example section for more details.
Parameters
- source - the file to scan for matching pattern
- target - the file to save all matched lines
- matchPattern - the pattern to match. This is regular expression, matched a line at a time
Example
source.txt (shown only the first 50 lines)
matchPattern (line contains qu)
Script:
target.txt (17 lines found with qu)
