 Most software that runs on Linux can run on FreeBSD using an optional built @-@ in compatibility layer . Hence , most Linux binaries can be run on FreeBSD , including some proprietary applications distributed only in binary form . This compatibility layer is not an emulation ; Linux 's system call interface is implemented in the FreeBSD 's kernel and hence , Linux executable images and shared libraries are treated the same as FreeBSD 's native executable images and shared libraries . Additionally , FreeBSD provides compatibility layers for several other Unix @-@ like operating systems , in addition to Linux , such as BSD / OS and <unk> , however , it is more common for users to compile those programs directly on FreeBSD . 
