relup(5) Release upgrade file


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.


In a target system, the release upgrade file is to be located in directory $ROOT/releases/Vsn.

The relup file contains one single Erlang term, which defines the instructions used to upgrade the release. The file has the following syntax:

  [{UpFromVsn, Descr, Instructions}, ...],
  [{DownToVsn, Descr, Instructions}, ...]}.
Vsn = string():
Current release version.
UpFromVsn = string():
Earlier version of the release to upgrade from.
Descr = term():
A user-defined parameter passed from the function systools:make_relup/3,4. It is used in the return value of release_handler:install_release/1,2.
A list of low-level release upgrade instructions, see appup(5). 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():
Earlier version of the release to downgrade to.