Handle unset MANPATH more gracefully to avoid overwriting system man pages

[Amrithasuresh]

Hi Lmod team,

I recently contributed a fix a bug where many module files unintentionally override the system MANPATH openhpc/ohpc#2095. I was redirected here to start a conversation about this issue. I'm new to these repositories, so I’d really appreciate any guidance or pointers on how I can contribute effectively.

The issue

This is my understanding. In Rocky Linux 9, the MANPATH environment variable is not set by default.

When Lmod loads a module that includes a line like:

prepend-path MANPATH /opt/moduleX/share/man

it replaces the MANPATH entirely — making man pages like man bash, man ls, etc., disappear unless a colon prefix is manually added:

prepend-path MANPATH :/opt/moduleX/share/man

[rtmclay]

This issue is handled by the Lmod startup scripts. Your system needs to have the following. This is found lmod/profile

  #
  # If MANPATH is empty, Lmod is adding a trailing ":" so that
  # the system MANPATH will be found
  if [ -z "${MANPATH:-}" ]; then
    export MANPATH=:
  fi

As this is discussed in the lmod documentation: https://lmod.readthedocs.io/en/latest/030_installing.html

On this web page the documentation recommends that sites do:

ln -s /opt/apps/lmod/lmod/init/profile        /etc/profile.d/z00_lmod.sh

Where /opt/apps/lmod/lmod is where Lmod is installed.

It looks like your installation of openhpc has issues. You should look at how Lmod is installed on your system and that the lmod/profile is linked to /etc/profile.d.

Also since you are on a Rocky 9 system, you much have

if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi

at the top of your ~/.bashrc. This guarantees that the system bashrc is source in interactive non-login shells.