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Setting the OMERO_HOME environment variable


OMERO_HOME should be considered strictly internal to OMERO and be reserved for development or “power usage”.


OMERO_HOME defines the root deployment directory to be used by OMERO command line tools.

Setting it allows to switch between different versions of applications or libraries during development.


Despite a familiar-sounding name, OMERO_HOME does not denote the server installation directory.


As a “power switch”, OMERO_HOME will override the directory layout as detected by the bin/omero family of utilities.

This could cause hard-to-detect problems at runtime. Environments hosting multiple OMERO versions would be particularly prone to such side effects, as illustrated below.

# Installation directory layout:
# /opt
#   +-- OMERO.server-version-4.4.10
#   +-- OMERO.server-version-5.0.0

# OMERO-4 was first installed, and is conveniently referenced through OMERO_HOME
$ echo $OMERO_HOME
> /opt/OMERO.server-version-4.4.10

# Update the configuration for OMERO-4
$ /opt/OMERO.server-version-4.4.10/bin/omero config set 'omero_4_database'
$ /opt/OMERO.server-version-4.4.10/bin/omero config get
> omero_4_database

# Update the configuration for OMERO-5
$ /opt/OMERO.server-version-5.0.0/bin/omero config set 'omero_5_database'
$ /opt/OMERO.server-version-5.0.0/bin/omero config get
> omero_5_database

# Double check the OMERO-4 configuration...
# Using OMERO_HOME has taken precedence over the current directory
# The OMERO-4 server instance has been mistakenly updated to point at
# a version 5 database schema.
# Furthermore, the issue might go unnoticed until the next OMERO-4 restart.
$ /opt/OMERO.server-version-4.4.10/bin/omero config get
> omero_5_database


  • If you are using an environment variable to define the server installation root, choose a different name, as represented by OMERO_PREFIX in this documentation.
  • If you are nevertheless using OMERO_HOME in your local environment, it is worth checking for potentially lingering global definitions (eg. .bashrc, .profile, /etc/profile.d).