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
- UNIX comes with its own tools such as SAM on HP-UX.
- Suse Linux comes with Yast
- 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:
- HP-UX - /sbin/init.d
- AIX - /etc/rc.d/init.d
- 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:
- Software installation procedure
- Hardware device names
- Various admin commands or utilities
- Software RAID devices and mirroring
- Logical volume management
- Package management
- Patch management
UNIX Operating System Names
A few popular names:
- HP-UX
- IBM AIX
- Sun Solairs
- Mac OS X
- IRIX
Linux Distribution (Operating System) Names
A few popular names:
- Redhat Enterprise Linux
- Fedora Linux
- Debian Linux
- Suse Enterprise Linux
- Ubuntu Linux
Common Things Between Linux & UNIX
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)
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: