Date in Filename

SQLMan has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Date in Filename by chip (Curate) on May 19, 2003 at 16:04 UTC
Reading `perldoc localtime` will help you: `my ($y,$m,$d) = (localtime)[5,4,3]; my $file = sprintf("errors.%04d-%02d-%02d", $y+1900, $m+1, $d); open ERRORS, '>>', $file;` [download] -- Chip Salzenberg, Free-Floating Agent of Chaos	[reply] [d/l] [select]
Re: Date in Filename by halley (Prior) on May 19, 2003 at 16:10 UTC
Whatever method you use, I recommend dates in the sortable format: "YYYY-MM-DD.hh-mm-ss". `my @now = localtime(); my $timestamp = sprintf("%04d-%02d-%02d.%02d-%02d-%02d", $now[5]+1900, $now[4]+1, $now[3], $now[2], $now[1], $now[0]); my $filename = "error.$timestamp.log";` [download] -- `[ e d @ h a l l e y . c c ]`	[reply] [d/l]
Re: Re: Date in Filename by sauoq (Abbot) on May 19, 2003 at 21:22 UTC
I agree that dates should be in a sortable format. For filenames, I often use something like `YYYYMMDD_HHMMSS-filename`. It varies because sometimes I only need the date; sometimes I don't need seconds; etc. It doesn't much matter one way or the other, but I do think that, if human readablity is a goal, different separation characters for date components and time components are helpful. So, how about ISO 8601? `YYYY-MM-DDTHH:MM:SS`. Several CPAN modules already handle it... -sauoq "My two cents aren't worth a dime.";	[reply]
Re: Date in Filename by jdporter (Paladin) on May 19, 2003 at 16:06 UTC
To get a useful short string from a date, I'd typically do something like this: `my( $sec, $min, $hour, $mday, $mon, $year ) = gmtime; my $datestamp = sprintf "%04d%02d%02d-%02d%02d", $year+1900, $mon+1, $mday, $hour, $min, $sec;` [download] Then you could include that in a file name, and open STDERR to it: `my $error_log = "error-$datestamp"; open STDERR, "> $error_log" or warn "Error redirecting stderr to $error_log: $!\n";` [download] Thereafter, all writes to stderr (including from `warn` and `die`) will go to that file. jdporter The 6th Rule of Perl Club is -- There is no Rule #6.	[reply] [d/l] [select]
Re(2): Date in Filename by chip (Curate) on May 19, 2003 at 16:08 UTC
Why `gmtime`? -- Chip Salzenberg, Free-Floating Agent of Chaos	[reply] [d/l]
Re: Re(2): Date in Filename by jdporter (Paladin) on May 19, 2003 at 18:22 UTC
There are various good reasons. One that I find compelling is that in this Internet Age, where I am and where my process runs might not be in the same timezone. Indeed, we might have many users in many timezones, and many servers in many timezones. I'm finding `localtime` to be rapidly diminishing in usefulness. jdporter The 6th Rule of Perl Club is -- There is no Rule #6.	[reply] [d/l]
Re: Re(2): Date in Filename by benn (Vicar) on May 19, 2003 at 16:52 UTC
Maybe to avoid any ambiguity with DST? Otherwise, the error log could overwrite itself during the 'switching hour'. Cheers,Ben.	[reply]
Re: Date in Filename by Corion (Patriarch) on May 19, 2003 at 16:04 UTC
Provided that your script name does not contain the percent sign : `use strict; use POSIX; my $filename = strftime "$0.%Y%m%d-%H%M%S.log", localtime();` [download] `strftime` is a really cool function for timestamps, but documentation is scarce. The DateTime module has more/better documentation on the format strings than the stock Perl/POSIX documentation. `perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ; # The $d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider ($c = $d->accept())->get_request(); $c->send_response( new #in the HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' # web` [download]	[reply] [d/l] [select]
Re: Re: Date in Filename by chip (Curate) on May 19, 2003 at 16:06 UTC
Tsk, passing unchecked data (`$0`) to `strftime` ... shame! What if somebody creates a symlink to the script, and that symlink's name contains a "%"; or what if there's a "%" in the path leading to the script? Then `strftime` is gonna get Really Mad, that's what. -- Chip Salzenberg, Free-Floating Agent of Chaos	[reply] [d/l] [select]
Re: Date in Filename by cciulla (Friar) on May 19, 2003 at 16:10 UTC
Try hitting "perldoc -f localtime". For example, `use POSIX qw(strftime); $now_string = strftime "error%Y-%m-%d.txt", localtime; print "$now_string\n";` [download] Update: I gotta learn to type faster. :) Update: Noticed a bug. C²	[reply] [d/l]