@node ax_build_date_epoch
@unnumberedsec ax_build_date_epoch

@majorheading Synopsis

@smallexample
AX_BUILD_DATE_EPOCH(VARIABLE[, FORMAT[, ACTION-IF-FAIL]])
@end smallexample

@majorheading Description

Sets VARIABLE to a string representing the current time.  It is
formatted according to FORMAT if specified, otherwise it is formatted as
the number of seconds (excluding leap seconds) since the UNIX epoch (01
Jan 1970 00:00:00 UTC).

If the SOURCE_DATE_EPOCH environment variable is set, it uses the value
of that variable instead of the current time.  See
https://reproducible-builds.org/specs/source-date-epoch).  If
SOURCE_DATE_EPOCH is set but cannot be properly interpreted as a UNIX
timestamp, then execute ACTION-IF-FAIL if specified, otherwise error.

VARIABLE is AC_SUBST-ed.

@majorheading Source Code

Download the
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_build_date_epoch.m4,latest
version of @file{ax_build_date_epoch.m4}} or browse
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=history;f=m4/ax_build_date_epoch.m4,the
macro's revision history}.

@majorheading License

@w{Copyright @copyright{} 2016 Eric Bavier @email{bavier@@member.fsf.org}}

This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
Public License for more details.

You should have received a copy of the GNU General Public License along
with this program. If not, see <https://www.gnu.org/licenses/>.

As a special exception, the respective Autoconf Macro's copyright owner
gives unlimited permission to copy, distribute and modify the configure
scripts that are the output of Autoconf when processing the Macro. You
need not follow the terms of the GNU General Public License when using
or distributing such scripts, even though portions of the text of the
Macro appear in them. The GNU General Public License (GPL) does govern
all other use of the material that constitutes the Autoconf Macro.

This special exception to the GPL applies to versions of the Autoconf
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exception to the GPL to apply to your modified version as well.