What does the --pre option in pip signify?

Question

I saw on this page that pip install neo4j-doc-manager --pre was used. What does the --pre flag mean?

Answer 1

The pip install command also supports a --pre flag that will enable installing pre-releases and development releases.

Source.

Answer 2

It tells pip to include pre-release versions of packages when searching for the latest version.

From the pip install reference documentation:

Include pre-release and development versions. By default, pip only finds stable versions.

See the section on Pre-release Versions:

Starting with v1.4, pip will only install stable versions as specified by PEP426 by default. If a version cannot be parsed as a compliant PEP426 version then it is assumed to be a pre-release.

The neo4j-doc-manager package currently has 5 releases out; one 'stable' 0.1.0 release and 4 devX releases which are newer, see the machine-readable list of releases. Without the --pre switch the 0.1.0 release would be installed, with the switch (as of this writing) 1.0.0.dev11 would be installed instead.