How do I convert an epoch timestamp to a human readable format on the cli?

Question

How do I convert an epoch timestamp to a human readable format on the cli? I think there's a way to do it with date but the syntax eludes me (other ways welcome).

Answer 1

On *BSD:

date -r 1234567890

On Linux (specifically, with GNU coreutils ≥5.3:

date -d @1234567890

With older versions of GNU date:

date -d '70-1-1 + 1234567890 sec'

If you need portability, you're out of luck. The only time you can format with a POSIX shell command (without doing the calculation yourself) line is the current time. In practice, Perl is often available:

perl -le 'print scalar localtime $ARGV[0]' 1234567890

Answer 2

date -d @1190000000 Replace 1190000000 with your epoch

Answer 3

$ echo 1190000000 | perl -pe 's/(\d+)/localtime($1)/e' 
Sun Sep 16 20:33:20 2007

This can come in handy for those applications which use epoch time in the logfiles:

$ tail -f /var/log/nagios/nagios.log | perl -pe 's/(\d+)/localtime($1)/e'
[Thu May 13 10:15:46 2010] EXTERNAL COMMAND: PROCESS_SERVICE_CHECK_RESULT;HOSTA;check_raid;0;check_raid.pl: OK (Unit 0 on Controller 0 is OK)

Answer 4

The two I frequently use are:

$ perl -leprint\ scalar\ localtime\ 1234567890
Sat Feb 14 00:31:30 2009

and

$ tclsh
% clock format 1234567890
Sa Feb 14 00:31:30 CET 2009