Make defined modulepaths persist over sudo

When running a command as another user with sudo, current user environment is most of the time flushed for security concerns. As a result, if one would like to use the modulecmd.tcl script in such context, an error is returned as modulecmd.tcl does not find modulepath defined (MODULEPATH variable is not set). Following recipe describes how to ensure the default modulepaths are set every time the modulecmd.tcl script is run.


Every time the modulecmd.tcl script is run, it evaluates during its start-up phase a global RC file following the same kind of evaluation than for modulefiles.

To ensure modulepaths are always defined, a check could be added in this global RC file to verify at least one modulepath is set (thanks to the is-used Tcl modulefile command). If no modulepath is found set, the .modulespath configuration file, which contains the default modulepaths, can be parsed to enable on the fly the default modulepaths (with module use Tcl modulefile command).

Global RC file

# ensure MODULEPATH is always defined, use content of .modulespath config file
# to initialize it if not defined
if {![is-used] && [file readable /usr/share/Modules/init/.modulespath]} {
    set fid [open /usr/share/Modules/init/.modulespath r]
    set fdata [split [read $fid] "\n"]
    close $fid
    foreach fline $fdata {
        if {[regexp "^\\s*(.*?)\\s*(#.*|)\$" $fline match patharg] == 1
            && $patharg ne {}} {
            eval module use --append [split $patharg :]

Compatible with Modules v4.1+


Copy the global RC file of this recipe in the configuration directory:

$ cp example/modulepaths-persist-over-sudo/rc /usr/share/Modules/etc/

The location of the .modulespath file defined in the proposed RC script should be adapted to reflect the location where this file is installed on your setup.

Usage example

Without the proposed RC file installed, MODULEPATH environment variable is lost through the sudo call:

$ sudo $MODULES_CMD bash avail >/dev/null
ERROR: No module path defined

Once RC file is installed, flushed MODULEPATH is restored on the fly based on .modulespath configuration file:

$ sudo $MODULES_CMD bash use >/dev/null
Search path for module files (in search order):

Thus available modulefiles are found again:

$ sudo $MODULES_CMD bash avail >/dev/null
--------------- /usr/share/Modules/modulefiles ---------------
dot  module-git  module-info  modules  null  use.own