Related question is "Datetime To Unix timestamp", but this question is more general.
I need Unix timestamps to solve my last question. My interests are Python, Ruby and Haskell, but other approaches are welcome.
What is the easiest way to generate Unix timestamps?
First of all, the Unix 'epoch' or zero-time is 1970-01-01 00:00:00Z (meaning midnight of 1st January 1970 in the Zulu or GMT or UTC time zone). A Unix time stamp is the number of seconds since that time - not accounting for leap seconds.
Generating the current time in Perl is rather easy:
perl -e 'print time, "\n"'
Generating the time corresponding to a given date/time value is rather less easy. Logically, you use the strptime() function from POSIX. However, the Perl POSIX::strptime module (which is separate from the POSIX module) has the signature:
($sec, $min, $hour, $mday, $mon, $year, $wday, $yday) =
POSIX::strptime("string", "Format");
The function mktime in the POSIX module has the signature:
mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = 0)
So, if you know the format of your data, you could write a variant on:
perl -MPOSIX -MPOSIX::strptime -e \
'print mktime(POSIX::strptime("2009-07-30 04:30", "%Y-%m-%d %H:%M")), "\n"'
The unix 'date' command is surprisingly versatile.
date -j -f "%a %b %d %T %Z %Y" "`date`" "+%s"
Takes the output of date, which will be in the format defined by -f, and then prints it out (-j says don't attempt to set the date) in the form +%s, seconds since epoch.