Perl regex to act on a file from the command line

Question

In a file, say xyz.txt i want to replace the pattern of any number followed by a dot example:1.,2.,10.,11. etc.. with a whitespace. How to compose a perl command on the comm

Answer 1

This HAS to be a Perl oneliner?

perl -i -pe  's/\d+\./ /g' 

The Perl command line options: -i is used to specify what happens to the input file. If you don't give it a file extension, the original file is lost and is replaced by the Perl munged output. For example, if I had this:

perl -i.bak -pe  's/\d+\./ /g' 

The original file would be stored with a .bak suffix and itself would contain your output.

The -p means to enclose your Perl program in a print loop that looks SOMEWHAT like this:

while ($_ = <>) {
    
    print "$_";
}

This is a somewhat simplified explanation what's going on. You can see the actual perl loop by doing a perldoc perlrun from the command line. The main idea is that it allows you to act on each line of a file just like sed or awk.

The -e simply contains your Perl command.

You can also do file redirection too:

perl -pe  's/\d+\./ /g' < xyz.txt > xyz.txt.out