use Modern::Perl;

use Modern::Perl;

say '  IP address: 10.10.10.10' =~ /IP\s+address:\s+([^\s]+)/;
say 'IP address: 10.10.10.10' =~ /IP\s+address:\s+([^\s]+)/;
say '  IP address: 10.10.10.10' =~ /^\s*IP\s+address:\s+([^\s]+)/;
say 'IP address: 10.10.10.10' =~ /^\s*IP\s+address:\s+([^\s]+)/;
[download]

Output:

10.10.10.10
10.10.10.10
10.10.10.10
10.10.10.10
[download]

Update: Ah! hmb104 was referring to using split, not the regex (which isn't attempting to match at the beginning of a line and is fully anchored w/o mentioning the spaces before "IP address:").