break-module-exports

#!/bin/bash

set -o errexit \
    -o nounset \
    -o pipefail \
    -o noclobber

function print_help() {
    echo "Usage: $0 <modules install prefix>"
    echo ""
    echo "This script creates and links a copy of a Tcl Env Modules"
    echo " bash init script, appending commands to unexport all"
    echo " the module shell functions."
    echo "This is done because qrsh -- which we use to run MPI tasks"
    echo " on compute nodes -- cannot handle exported shell functions"
    echo " and produces very noisy errors if they are present."
    echo ""
    echo "Because this performs the symlink as the final operation,"
    echo " it should be safe to run live."
    echo ""
}

if [[ "$#" != 1 ]]; then
    print_help >&2
    exit 1
fi

if [[ "$1" == "-h" ]] || [[ "$1" == "--help" ]]; then
   print_help 
   exit 0
fi

target_dir="$1"
target_file="$target_dir/init/bash"

if [[ ! -w "$target_file" ]]; then
    echo "Error: No writable bash init file found in provided directory" >&2
    exit 2
fi

if grep --quiet -e '^#UNEXPORTED_FLAG_COMMENT' "$target_file"; then
    echo "Detected UNEXPORTED_FLAG_COMMENT in target file: unexports already added." >&2
    exit 0
fi

if [[ -f "$target_file.old" ]]; then
    echo "Error: Flag not found, but found existing backup of bash init file in: $target_file.old" >&2
    echo "       This script does not know how to proceed in this situation." >&2
    exit 3
fi

# Okay let's get on with it

echo "Making copies of old bash init file..." >&2
cp -v "$target_file" "$target_file.old"
cp -v "$target_file" "$target_file.no_export_fs"

echo "Appending unexports to copy..." >&2
cat >>"$target_file.no_export_fs" <<'EOF'
# unexports all module shell functions to avoid a bug in qrsh
declare -Fx module      && export -nf module       || true
declare -Fx ml          && export -nf ml           || true
declare -Fx _module_raw && export -nf _module_raw  || true
declare -Fx switchml    && export -nf switchml     || true
#UNEXPORTED_FLAG_COMMENT
# ^-- this means we can check whether we've made the change to the init file
EOF

echo "Force-linking old filename to new copy..." >&2
ln -vsf "${target_file##*/}.no_export_fs" "$target_file"

echo "Done." >&2