postfix/postfix.aliasesdb

#!/bin/bash

ALIASESDB_STAMP=/var/lib/misc/postfix.aliasesdb-stamp

make_aliasesdb() {
        local MAP=""
        local ALIASESDB="$(/usr/sbin/postconf -h alias_database)"
        [ "$ALIASESDB" = "hash:/etc/aliases" ] && MAP="db"
        [ "$ALIASESDB" = "lmdb:/etc/aliases" ] && MAP="lmdb"

        if [ "$MAP" = "db" -o "$MAP" = "lmdb" ]
        then
                # /etc/aliases.db|lmdb may be used by other MTA, make sure nothing
                # has touched it since our last newaliases call
                [ /etc/aliases -nt /etc/aliases.$MAP ] ||
                        [ "$ALIASESDB_STAMP" -nt /etc/aliases.$MAP ] ||
                        [ "$ALIASESDB_STAMP" -ot /etc/aliases.$MAP ] || return 0
                /usr/bin/newaliases
                touch -r /etc/aliases.$MAP "$ALIASESDB_STAMP"
        else
                /usr/bin/newaliases
        fi
}

make_aliasesdb