   definition of unix
  What exactly makes a system unix like?  I have been using unix like systems for a while, but I have never gone very deep into the system itself, as I like to keep my software portable.  But now I am delving in. 
  The filesystem hierarchy, system calls (like fork()), being written in C (which affects the execution model and the system call or library model), the presence of something that works enough like bourne shell to run most sh scripts.A descriptor like "unix-like" is inherently defined by what makes it different from other operating systems.  Really, this is a hierarchical filesystem (others have database like filesystems or even abstract persistence entirely, so that all allocated storage is written to disk automatically.  This is particularly useful for distributed OSes, for which memory allocation is as complicated as writing to disk) that abstracts the underlying medium (i.e. everything is under /, even portable media, which distinguishes it from Windows). ;  all of that could be a wrapper around any os.  if windows had cygwin replace thesystem shell, dlls, etc would that make it unix-like?And how does mach fit in?  it was written in c++, and considered a *nix.  well, the os is.  the microkernel is just a kernel.   [edited by - witchcraven on May 12, 2004 4:36:47 AM];  There is a standard known as POSIX which all Unix systems conform to. There are also other common things, like the System V architecture.Windows can be made POSIX compatible, but it doesn''t ship like that. No, not Cygwin; that other MS thing of which I forget the name. ;quote:Original post by Promit  There is a standard known as POSIX which all Unix systems conform to. There are also other common things, like the System V architecture.Windows can be made POSIX compatible, but it doesn''t ship like that. No, not Cygwin; that other MS thing of which I forget the name.   Windows Services for UNIX? ;  The most important specification as to whether an OS is UNIX is the Single UNIX Specification.;quote:Original post by aftermath  quote:Original post by Promit   There is a standard known as POSIX which all Unix systems conform to. There are also other common things, like the System V architecture.Windows can be made POSIX compatible, but it doesn''t ship like that. No, not Cygwin; that other MS thing of which I forget the name.   Windows Services for UNIX?   Aye, that''s the one. ;  Thanks Mayrel ;  UNIX is a trademark of the X/Open group. ;quote:Original post by Witchcraven  What exactly makes a system unix like?  I have been using unix like systems for a while, but I have never gone very deep into the system itself, as I like to keep my software portable.  But now I am delving in.   See Mr Raymond''s book The Art Of Unix Programming. It explains what Unix does and why it does things the way it does with comparisons to other OS''s and the way they do things.dave j 