How to set "SINGULARITY_SHELL" variable?

[Heng-Zhou]

I wish to set SINGULARITY_SHELL variable which is used in /.singularity.d/actions/shell to control what shell to use and how to start it. I tried to set it in %environment and %post, but none of them work. So, how to set this variable?

[Heng-Zhou]

It is set in %environment section. I did not spot it out previously.

[dtrudg]

Please see the singularity shell --help output and the environment variable documentation. The shell is set via the -s or --shell flag:

  -s, --shell string                  path to program to use for
                                      interactive shell

Or by setting SINGULARITY_SHELL on the host.

Manipulating the variable inside a definition file / container directly is not something that we advise. The exact code of the action scripts is considered to be an internal detail, and the way that the action scripts are implemented in newly built containers may change in future.

The intended / supported behaviour is only by setting SINGULARITY_SHELL on the host, or use the -s / --shell flag.