NAME
relup - Release upgrade file
DESCRIPTION
The release upgrade file describes how a release is upgraded in a
running system.
This file is automatically generated by systools:make_relup/3,4, using
a release resource file ( .rel), application resource files ( .app) and
application upgrade files ( .appup) as input.
FILE SYNTAX
In a target system, the release upgrade file should be located in the
OTP_ROOT/erts-EVsn/Vsn directory.
The relup file contains one single Erlang term, which defines the
instructions used to upgrade the release. The file has the following
syntax:
{Vsn,
[{UpFromVsn, Descr, Instructions}, ...],
[{DownToVsn, Descr, Instructions}, ...]}.
* Vsn = string() is the current version of the release. .br .br
* UpFromVsn = string() is an earlier version of the release to
upgrade from. .br .br
* Descr = term() is a user defined parameter passed from the
systools:make_relup/3,4 function. It will be used in the return
value of release_handler:install_release/1,2. .br .br
* Instructions is a list of low-level release upgrade instructions,
see appup(4). .br .br It consists of the release upgrade
instructions from the respective application upgrade files (high-
level instructions are translated to low-level instructions), in
the same order as in the start script. .br .br
* DownToVsn = string() is an earlier version of the release to
downgrade to. .br .br
When upgrading from UpFromVsn with release_handler:install_release/1,2,
there does not have to be an exact match of versions, but UpFromVsn can
be a sub-string of the current release version.
SEE ALSO
app(4), appup(4), rel(4), release_handler(3erl), systools(3erl)