Alexey Fedorchuk's book "Accessible UNIX: Linux, FreeBSD, DragonFlyBSD, NetBSD, OpenBSD" is addressed to the widest masses, the bulk of which will be quite experienced computer users who do not have the skills to work in UNIX systems, but who want to get acquainted with the world of POSIX systems (Unix, Linux, FreeBSD and other UNIX-like operating systems) and join it.