Hi Lee, On Wed, 12 Jun 2013 06:44:19 +0200 lee <l...@yun.yagibdah.de> wrote:
> Hi, > > what I'm trying to do is create a list of sha-2 sums of files the names > of which are stored in a file. The purpose is to verify from time to > time whether any of the listed files have been modified or not in the > meantime. > > So I can read the list of file names; what I don't understand is what > the most efficient way would be to create a sha-2 sum for a file. > > It doesn't even need to be sha-2 since there are no security issues > involved. The only purpose is to figure out reliably if any of the > files on the list have been modified or not. I don't want to go by file > modification dates because that isn't entirely reliable. > > I've been googling for examples of how to create a sha-2 sum of a file > in perl without success. What I'm looking for is something like: In general, you should not Google for Perl information, because Google tends to find outdated results. Instead, use MetaCPAN - http://metacpan.org/ with a fallback to DuckDuckGo - https://duckduckgo.com/ . > > $hash = create_sha2_sum( $filename); > This MetaCPAN search should be instructive: https://metacpan.org/search?q=sha Especially https://metacpan.org/module/Digest::SHA You can write create_sha2_sum like that (untested): <CODE> sub create_sha2_sum { my ($filename) = @_; my $sha = Digest::SHA->new(512); $sha->addfile($filename); return $sha->hexdigest(); } </CODE> > Do you know of any examples I could look at? Or is there a better way > to figure out if a file has been modified? > You can try looking at the mtime() from http://perldoc.perl.org/File/stat.html , but that's not as reliable as calculating a checksum of the contents. Regards, Shlomi Fish -- ----------------------------------------------------------------- Shlomi Fish http://www.shlomifish.org/ Why I Love Perl - http://shlom.in/joy-of-perl Doing linear scans over an associative array is like trying to club someone to death with a loaded Uzi. — Larry Wall Please reply to list if it's a mailing list post - http://shlom.in/reply . -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
