(cvs.info.gz) Seconds since the Epoch

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 A.6.8 Seconds since the Epoch
 -----------------------------
 
 If you precede a number with `@', it represents an internal time stamp
 as a count of seconds.  The number can contain an internal decimal
 point (either `.' or `,'); any excess precision not supported by the
 internal representation is truncated toward minus infinity.  Such a
 number cannot be combined with any other date item, as it specifies a
 complete time stamp.
 
    Internally, computer times are represented as a count of seconds
 since an epoch--a well-defined point of time.  On GNU and POSIX
 systems, the epoch is 1970-01-01 00:00:00 UTC, so `@0' represents this
 time, `@1' represents 1970-01-01 00:00:01 UTC, and so forth.  GNU and
 most other POSIX-compliant systems support such times as an extension
 to POSIX, using negative counts, so that `@-1' represents 1969-12-31
 23:59:59 UTC.
 
    Traditional Unix systems count seconds with 32-bit two's-complement
 integers and can represent times from 1901-12-13 20:45:52 through
 2038-01-19 03:14:07 UTC.  More modern systems use 64-bit counts of
 seconds with nanosecond subcounts, and can represent all the times in
 the known lifetime of the universe to a resolution of 1 nanosecond.
 
    On most systems, these counts ignore the presence of leap seconds.
 For example, on most systems `@915148799' represents 1998-12-31
 23:59:59 UTC, `@915148800' represents 1999-01-01 00:00:00 UTC, and
 there is no way to represent the intervening leap second 1998-12-31
 23:59:60 UTC.
 

Info Catalog

(cvs.info.gz) Pure numbers in date strings

(cvs.info.gz) Date input formats

(cvs.info.gz) Specifying time zone rules