Difference Between Linux and UNIX

UNIX is copyrighted name only big companies are allowed to use the UNIX copyright and name, so IBM AIX andUnix_F   Sun Solaris and HP-UX all are UNIX operating systems. The Open Group holds the UNIX trademark in trust for the industry, and manages the UNIX trademark licensing program.Most UNIX systems are commercial in nature.

Linux is a UNIX Clone

But if you consider Portable Operating System Interface (POSIX) standards then Linux can be considered as UNIX. To quote from Official Linux kernel README file:

Linux is a Unix clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX compliance.

However, "Open Group" do not approve of the construction "Unix-like", and consider it misuse of their UNIX trademark.

Linux Is Just a Kernel

Linux is just a kernel. All Linux distributions includes GUI system + GNU utilities (such as cp, mv, ls,date, bash etc) + installation & management tools + GNU c/c++ Compilers + Editors (vi) + and various applications (such as OpenOffice, Firefox). However, most UNIX operating systems are considered as a complete operating system as everything come from a single source or vendor.

As I said earlier Linux is just a kernel and Linux distribution makes it complete usable operating systems by adding various applications. Most UNIX operating systems comes with A-Z programs such as editor, compilers etc. For example HP-UX or Solaris comes with A-Z programs.

License and cost

Linux is Free (as in beer [freedom]). You can download it from the Internet or redistribute it under GNU licenses. You will see the best community support for Linux. Most UNIX like operating systems are not free (but this is changing fast, for example OpenSolaris UNIX). However, some Linux distributions such as Redhat / Novell provides additional Linux support, consultancy, bug fixing, and training for additional fees.


Linux is considered as most user friendly UNIX like operating systems. It makes it easy to install sound card, flash players, and other desktop goodies. However, Apple OS X is most popular UNIX operating system for desktop usage.

Security Firewall Software

Linux comes with open source netfilter/iptables based firewall tool to protect your server and desktop from the crackers and hackers. UNIX operating systems comes with its own firewall product (for example Solaris UNIX comes with ipfilter based firewall) or you need to purchase a 3rd party software such as Checkpoint UNIX firewall.

Backup and Recovery Software

UNIX and Linux comes with different set of tools for backing up data to tape and other backup media. However, both of them share some common tools such as tar, dump/restore, and cpio etc.

File Systems

  • Linux by default supports and use ext3 or ext4 file systems.
  • UNIX comes with various file systems such as jfs, gpfs (AIX), jfs, gpfs (HP-UX), jfs, gpfs (Solaris).

System Administration Tools

  1. UNIX comes with its own tools such as SAM on HP-UX.
  2. Suse Linux comes with Yast
  3. Redhat Linux comes with its own gui tools called redhat-config-*.

However, editing text config file and typing commands are most popular options for sys admin work under UNIX and Linux.

System Startup Scripts

Almost every version of UNIX and Linux comes with system initialization script but they are located in different directories:

  1. HP-UX – /sbin/init.d
  2. AIX – /etc/rc.d/init.d
  3. Linux – /etc/init.d

End User Perspective

The differences are not that big for the average end user. They will use the same shell (e.g. bash or ksh) and other development tools such as Perl or Eclipse development tool.

System Administrator Perspective

Again, the differences are not that big for the system administrator. However, you may notice various differences while performing the following operations:

  1. Software installation procedure
  2. Hardware device names
  3. Various admin commands or utilities
  4. Software RAID devices and mirroring
  5. Logical volume management
  6. Package management
  7. Patch management
UNIX Operating System Names

A few popular names:

  1. HP-UX
  2. IBM AIX
  3. Sun Solairs
  4. Mac OS X
  5. IRIX
Linux Distribution (Operating System) Names

A few popular names:

  1. Redhat Enterprise Linux
  2. Fedora Linux
  3. Debian Linux
  4. Suse Enterprise Linux
  5. Ubuntu Linux

Common Things Between Linux & UNIX

Both share many common applications such as:

  1. GUI, file, and windows managers (KDE, Gnome)
  2. Shells (ksh, csh, bash)
  3. Various office applications such as OpenOffice.org
  4. Development tools (perl, php, python, GNU c/c++ compilers)
  5. Posix interface

You can see the original article here

To put it very generically, Linux is an operating system kernel, and UNIX is a certification for operating systems. The UNIX standard evolved from the original Unix system developed at Bell Labs. After Unix System V, it ceased to be developed as a single operating system, and was instead developed by various competing companies, such as Solaris (from Sun Microsystems), AIX (from IBM), HP-UX (from Hewlett-Packard), and IRIX (from Silicon Graphics). UNIX is a specification for baseline interoperability between these systems, even though there are many major architectural differences between them. Linux has never been certified as being a version of UNIX, so it is described as being "Unix-like." A comprehensive list of differences between Linux and "UNIX" isn’t possible, because there are several completely different "UNIX" systems.


About aronnirmal

A student pursuing Masters in Compter Applications. Intrested in Linux, Computer Hardware and networking,eco-enviorment related issues and politics.

Posted on December 2, 2010, in linux, Open source and tagged , , , , , , , , , , , , , , , , , , . Bookmark the permalink. 1 Comment.

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