I think there are some mistakes in build file which copy from 2016-09-01,http://files.directadmin.com/services/custombuild/2.0/custombuild/build,beacause there are some hints from:
[CODE[root@server custombuild]# ./build clean
: integer expression expected
: integer expression expected
./build: line 2506: [: : integer expression expected
[root@server custombuild]#
][/CODE]
[CODE[root@server custombuild]# ./build clean
: integer expression expected
: integer expression expected
./build: line 2506: [: : integer expression expected
[root@server custombuild]#
][/CODE]