_____________________________________________________
Jeff japhy Pinyan: Perl, regex, and perl hacker.
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;

You simply want to use ($first) = $line =~ /(\S*)/;
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I believe that the original poster also wanted to capture a series of blank spaces, if that was what occupied the first element of a line.

\S matches non-whitespace characters only. . .

. . . the split solutions seem much more well-suited.

--twerq

No, if you'll read the entire post, you'll notice that I said "... if the line begins with spaces or is empty, I just want to print out a blank line..." Anyway, the first two examples here do just what I'm looking for. Thanks, guys!

No, the original post says:

As you can see, if the line begins with spaces or is empty, I just want to print out a blank line so I can tell that there was something there.

He either wants the column of text, or nothing. That is what I give him.

_____________________________________________________
Jeff japhy Pinyan: Perl, regex, and perl hacker.
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;

Try one of these one-liners (they have the same output, but I thought the second might be a little easier to understand):

perl -ple '($_) = /^\S+/g' filename
perl -ple '$_ = (/^\S+/g)[0]' filename
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Basically, it reads a line, then sets it to the first group of non-whitespace stuff at the beginning of the line, and then prints the changed line out. Hope this helps!

His Royal Cheeziness

Here is a nice simple example. We read from the DATA file handle but it could just as well be a file handle you open with an open FILE, "<file.txt" or die "Oops $!\n"

while (<DATA>) {
   ($first) = $_ =~ m/^(\S+)/;
    print "$first\n";
}

__DATA__
This is a line.
Another line is here.
  Here's a line.

Line five is this one.
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The while iterates over the filehandle assigning each line to $_. The next line is a standard perl idiom to capture a regex match. We match all non whitespace at the begining of the each line. We specify the beginning with the ^ and the non whitespace with the \S the + after \S specifies 1 or more of (and as much as possible)

You can also do this with split. Split returns an array of values so (split/\s/,$_)[0] is the first value when we split $_ on whitespace. Note that in the example I don't bother to specify $_ as this is the default string that split works on.

while (<DATA>) {
    $first = (split/\s/)[0];
    print "$first\n";
}
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Getting completely carried away you can also do it using substr and index. Index gets you the postion of the first space and substr gets you the string.

while (<DATA>) {
    $first = substr $_, 0, index $_, " ";
    print "$first\n";
}
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Hope this helps.

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

Your question has already been answered. I just want to give you some hints for the more general case (n-th column or you need more than one column):

• Don't try to use a regex there, use split:

  my @columns = split /\s*/, $line;
  
  # or
  my $col3 = (split /\s*/, $line)[2]
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• Depending on what you would like to get, split on / /, /\s*/ or ' '. Or whatever your column delimter might be.

-- Hofmator