How can I match a pipe character followed by whitespace and another pipe?

Question

I am trying to find all matches in a string that begins with | |.

I have tried: if ($line =~ m/^\\\\\\|\\s\\\\\\|/) which didn\'t work. <

Answer 1

Pipe character should be escaped with a single backslash in a Perl regex. (Perl regexes are a bit different from POSIX regexes. If you're using this in, say, grep, things would be a bit different.) If you're specifically looking for a space between them, then use an unescaped space. They're perfectly acceptable in a Perl regex. Here's a brief test program:

my @lines = ;

for (@lines) {
    print if /^\| \|/;
}

__DATA__  
| | Good - space  
|| Bad - no space  
|   | Bad - tab  
 | | Bad - beginning space  
        Bad - no bars