one of the documented procedures in this installation of the ACS
apm_register_new_packages { -callback apm_dummy_callback }
What it does:
Looks for unregistered packages in the packages directory, registering them in the database if found.
Defined in: /web/philip/packages/acs-core/apm-procs.tcl

Source code:

arg_parser_for_apm_register_new_packages $args

    ns_log "Notice" "Scanning for new packages..."

    # Obtain paths and mtimes for the spec files of all installed packages, in order
    # to avoid reading spec files which haven't changed.
    db_foreach "
        select package_key, spec_file_path, spec_file_mtime
        from apm_packages
    " {
	set spec_file_paths($package_key) $spec_file_path
	set spec_file_mtimes($package_key) $spec_file_mtime

    # Loop through all directories in the /packages directory, searching each for a
    # .info file.
    set n_registered_packages 0
    foreach dir [lsort [glob -nocomplain "[acs_root_dir]/packages/*"]] {
	set package_key [file tail $dir]
	if { ![file isdirectory $dir] || [apm_ignore_file_p $dir] } {
	    apm_callback_and_log $callback "Skipping $package_key."

	# Locate the .info file for this package.
	if { [catch { set info_file [apm_package_info_file_path $package_key] } error] } {
	    apm_callback_and_log -severity Warning $callback "Unable to locate specification file for package $package_key: $error"

	# If the mtime for this package hasn't changed since the last time we
	# examined it, don't bother reregistering it.
	if { [info exists spec_file_paths($package_key)] &&  [file isfile $spec_file_paths($package_key)] &&  [file mtime $spec_file_paths($package_key)] == $spec_file_mtimes($package_key) } {
	    apm_callback_and_log $callback "[ad_make_relative_path $spec_file_paths($package_key)] has not changed; skipping."

	# Try to register the .info file in the database.
	if { [catch { set version_id [apm_register_package -callback $callback $info_file] } error] } {
	    apm_callback_and_log -severity Error $callback "Unable to register package $package_key: $error"

	    # Ensure that the package is not marked as installed, since we've established
	    # that there is no valid .info file in the filesystem!
	    db_dml "
                update apm_package_versions
                set    installed_p = 'f'
                where  package_id in (select package_id from apm_packages
                                      where package_key = '$package_key')
	} else {
	    incr n_registered_packages

	    array set version [apm_read_package_info_file $info_file]

	    # Remember that we've examined this .info file.
	    db_dml "
                update apm_packages
                set spec_file_path = '[db_quote $version(path)]',
                    spec_file_mtime = $version(mtime)
                where package_key = '$package_key'

	    # Mark this version of the package as installed, and other versions as un-installed.
	    db_dml "
                update apm_package_versions
                set    installed_p = decode(version_id, $version_id, 't', 'f')
                where  package_id in (select package_id from apm_packages
                                      where package_key = '$package_key')

    if { $n_registered_packages == 0 } {
	ns_log "Notice" "No new packages found."