Unix is the most portable operating system there is because it can run on wide variety of environments from PC's to mainframes. Every user has to have an account and security is set on every file and every directory.
Unix is inherently portable; this means that a program, script, or process may be moved from Unix system to Unix system with little effort or change (hence - portable).
Unix comes in multiple distributions some more secure than others. Much of the security also comes from how the system is configured. Most unix systems are fairly secure.
Unix is one of the more secure operating systems, but it would be difficult to give an exact answer. It is very easy (and possible) to make any operating system insecure. It takes individuals some amount of time to secure any operating system, and Unix is no exception to that.
"Portable Operating System Inferance (for Unix)
Importance Of Unix-support multiuser and multitasking.-adaptability and simplicity.-flexible file system.-excellent network environment.-portable.- provide better security.
POSIX stands for Portable Operating System Interface..
Unix was rewritten in the C Programming language and not in assembly language. The migration from assembly language to the higher-level language C resulted in much more portable software, requiring only a relatively small amount of machine-dependent code to be replaced when porting Unix to other computing platforms. (mihir)
vsftpd is an FTP server for unix-like systems that is specially built to be efficient and very secure (very secure FTP daemon).
flexibe, faster to run programme ,very secure , portability
flexibe, faster to run programme ,very secure , portability
Nitesh Dhanjani has written: 'HackNotes(tm) Linux and Unix Security Portable Reference'
A Unix shell can be obtained in Cygwin, a Unix compatibility layer used to compile Unix programs and run them on Windows. Microsoft also makes a shell known as "Windows PowerShell" which incorporates more Unix-like features than the standard command prompt.