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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.
* UpFromVsn = string() is an earlier version of the release to
upgrade from.
* 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.
* Instructions is a list of low-level release upgrade instructions,
see appup(4).
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.
* DownToVsn = string() is an earlier version of the release to
downgrade to.
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)