Difference Between Linux and UNIX

Posted on in Categories , last updated September 8, 2016

What is the difference between Linux and UNIX operating systems?

UNIX is copyrighted name only big companies are allowed to use the UNIX copyright and name, so IBM AIX and 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.

User-Friendly

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

A Sample UNIX Desktop Screenshot

UNIX Desktop - IRIX 6.5 Desktop
Fig.01: UNIX Desktop - IRIX 6.5 Desktop

A Sample Linux Desktop Screenshot

Linux KDE desktop environment
Fig.02: Linux KDE desktop environment

UNIX and Linux Hardware

Commercial UNIX hardware has more advanced initial boot options such as:

  • Decide how to boot
  • Check system health
  • Set hardware parameters etc

The BIOS that is standard in PCs which is used by Linux has few, of these features. UNIX hardware or servers are pretty expensive as compare to Linux server systems.

Further readings:

Following documents or URL should help anyone to get more idea:

(Image credit IRIX and KDE wikipedia articles)

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

313 comment

    1. That still doesn’t help the bimbo recruiter from the big investment bank on the phone “Sir, Sir my managers are very specific they want Unix type people-SIR, Sir I don’t think they want a Red Hat”

  1. Unix and linux both are multiuser operating system. Unix operating based on CUI(Character User Interface) and does not support pointing device, where as in linux opearating system; adding new features XWindows in Unix operating system and it is based on GUI(Graphical User Interface) i.e., it is like as DOS and Windows

            1. Linux has both CLI and GUI (via X window start it by cmd # startx) from cli;
              On the Other hand Unix is purely CLI, however many distribution has the GUI feature now. BSd unix for exmpl.

              1. I’m not sure where so much misinformation is coming from, but this bit about GUI vs CUI is just bunk. The X Window System including its use of mouse (“pointing device”) was developed on real UNIX systems 3/4 of a decade (1984 vs 1991) before Linux was even invented. All modern Unix systems support GUI as well as CLI interfaces, and have since before most of you were born. Please check on Wikipedia before blindly repeating false information.

    1. linux and unix ar standard cli. they both can run almost the same software, so the both suport gui. mac os is unix and has gui suport. most linux distributions have the possibility to use a bsd (=unix) kernel with the same gui you use with the linux kernel.

    1. Both share many common applications such as:

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

    2. linux is open source and unix is cloused source os it mean linux r freely available user can upgrade or invent commands n so many things r did but as per unix it leaglly perchase……there is no doubt that linux is clone of unix if u r able to handle linux so u must hv well handled unix also….if u have cartain doubt then mail me swati

  2. Great!!!

    I gained some valuable knowledge here!!!
    But still confused about the origin of these two!!!

    I m new to linux using Ubuntu 9.10 >>>
    Pls give me some tricks and tips for my Os…

        1. me too i m thinking the same tought.. on thing i want to get confirmed these are the OS’s MS, Mac, Apple, Linux. thats it i know. so wether UNIX And LINUX are same or different OS’s.

  3. Unix and linux both operating system is based in the multiuser/multing environment. and kernal
    based operating system. unix only suport the CUI but linux suport both CUI & GUI.
    basicaly this operating system is used in the network environment. it is very use full for security point of view.

  4. 1-unix is CUI whereas linux is GUI
    2-unix has pointer device linux dnthav
    3-unix is property software where as linux is open source
    4-unix is more secure than linux
    5-keranel of unix is in enhace in linux

  5. its intersting and knowlegable !!! but how they r originated !!!! and if linux is 4 free than wat is the beneifit of the company and linux is authorised or not ????

    1. this is also a question that has to be raised… more over Linux LTS is for some 18 months to 3 yrs. what about after that. do we need to purchase Original OS Disks or any improvements.

  6. UNIX is CUI……….But CUI means not character user interface………CUI means command user interface……….Unix is developed on C-language and C is a CUI which is Character user interface(CUI)…….so so many of us think that UNIX also Character user interface but its wrong……..UNIX is Command user interface……….

    1. Kernel is the main component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level.

      The kernel’s responsibilities include managing the system’s resources (the communication between hardware and software components).

  7. The OS has basically 2 parts 1.Kernel 2.Shell ….. Kernel is the part which deals with the system resources and hardware and shell is the part which deals with the application software. Whenever any OS is designed first its Kernel is designed.The same had happened in case of Linux

  8. Woah… thanks… this info is fueling my knowledge for explaining the real and indepth differences between Macs and Windows… God bless you sir ;)

  9. Wow…this is a load of FUD about UNIX. It has nothing to do with ONLY big companies.

    Instead UNIX is a trademark that signifies that the OS using it has passed specific tests and conforms the defined UNIX specification to handle interoperability. This is like POSIX which is also administered by The Open Group joinly with IEEE.

    Any OS can become UNIX-certified if the vendor chooses to try and can meet the standard. As far as I know, no Linux vendor (i.e. RedHat) has tried.

  10. Can someone explain what “A-Z programs” are? If you google, the sentence
    “Most UNIX operating systems comes with A-Z programs such as editor, compilers etc.”
    is repeated verbatim all over the place, with no explanation. The next sentence won’t clarify much, either:
    “For example HP-UX or Solaris comes with A-Z programs.”
    Thanks!

    1. Unix comes with all sort of utilities and command bundled from a single vendor such as IBM, HP, SUN/Oracle and so on. The single vendor provides you updates, patches, commands, installer, and management utilities (source #1).

      On other hand, Linux installs userland tools from GNU project (source #1). The installer scripts and management tools are often written by distro maintainers (source #2). Third party apps need to be downloaded and install as required (source #3). Also, you need to add additional repos to install binary software (such as EPEL or debian multimedia source #4).

      Hope this helps!

  11. It is interesting comparing screen shots of a bland Unix desktop compared to a nicely laid out Linux version. The Mac OS X is Unix certified and clearly has a very elegant and polished User Interface. The comparison between screen shots here implies that Linux desktops are more professional looking. In general that may be true, but not when comparing to the Mac. Being a Mac guy… just had to point that out.

  12. it is good to have ,,, such operating system…..linux is totally based on unix os … or we can say it’s xerox of unix .
    y i love unix OS ?
    =coz it come with fully loaded software .. Eg-(perl, php, python, GNU c/c++ compilers)
    which is important for us ,,,,,,,,,,,,

  13. Hi,

    I like to install Sun Solaris operating system in Laptop, for installing solaris OS, is there any PC configuration should be required or am using windows 7, i can install solaris OS using VM ware software?

    Any one can guide me?

    Thanks

  14. So, Linux differs from UNIX by:
    -being operatable on PC’s
    -open source and therefore free

    UNIX obviously :
    – runs on mainframe computers only
    – and must be legally purchased as it is closed source

    is this corect?

  15. so..linux and unix is a same thing? both compatible in a laptop or in cpu? means..when i want to change os from windows to ubuntu, i just uninstall windows or can the two os work together?

    1. for example,
      IBM — AIX, HP — HP-UX, Sun — Solaris.
      same is for linux also…linux can available free to use but unix is not …
      different versions of linux has numbers of same applications but in unix different applications for different versions…

      thnks to all …its very good work …….keep it (y).!!!!!!!!!!!!

  16. Hello,

    This is Hamid from Egypt, I am so interested to learn Unix. I found out that most of people in my country are tide up to Windows while I’ve had a quick look at Unix and I liked it so much. I am not asking you for any thing just to guide me to the right and true way to get the whole thing about it. Please tell me what to do to get it .

    With kindness always,
    Hamid Kamel

  17. i got more knowledge about this linux & unix this explanation helps me a lot for my future and also the reply of peoples explanation is also good .still provide me more about linux and unix

  18. Its a Good Explanation , Appriciating for the same.
    Adding few terms , Linux is not the same OS as compare to UNIX OS , it is developed the way it Actually looks like UNIX , in a Era , UNIX is being used in Telecommunication based Servers like Sun-Solaries Netra V440/v890/M3000/X4170 (All are Solaries based Unix OS) , Installed the Application on this Servers.

  19. Whenever i am searching about basics of unix, every other search comes up with basics of linux.
    is it because both of the are similar at base level? or am i missing something? since i have just started learning about unix, i am a bit confused whether leaning about one makes you understand the other then?

  20. Article is seriously flawed by omitting discussion of modern Unix-derived open-source systems such as OpenBSD (the guys who gave you OpenSSH, the PF firewall and other innovations), FreeBSD and NetBSD, all derived from Berkeley Unix, a version developed at UC Berkeley in the late 1970’s.

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