Which Linux distro is closest to Unix?

I would like to brush up on my Unix skills.


thanks

Probably FreeBSD or Slackware. Because they follow the BSD style init scripts etc.
Also, you could install ksh/csh if you want, if you feel comfortable in those shells.

Is FreeBSD considered Linux? (e.g. does it use the Linux kernel?) Also, I think there is OpenSolaris.

But, what is the real objective? For a lot of scripting and other programming, it's all pretty similar. To administer specific systems, however, you probably want to learn those systems.

'Debian' was the most familiar to me after using Solaris back in the early 1990s. I'd say there were far more differences between UNIX systems than between any Linux distros. Anyone care for IRIX? SCO?

Not sure if this was a rhetorical question or not, but no, FreeBSD isn't Linux - it definitely does not use the Linux kernel.

I think it depends more on the architecture of Unix.
SCO, for example, based on SysV. FreeBSD has a little bit another structure.
Linux tries to cover both of them. Thus, you can use SysV syntax: ps -lf as well as BSD: ps aux.
However, the boot process differs between distros. RedHat and Mandriva use SysV style (one file in /etc/rc.d/ for each service), whereas Debian and SuSE (please correct me if I wrong) use one file for starting all the services.
Another difference is in software installation way.

I'd suggest you to try using several distros (for not long time), get your own opinion and choose the best for you.

Debian has been using SysV for at least 8 years; I remember a more BSD-like option used to be available, but before the year 2000 I know nothing of Debian. Debian has /etc/rcS.d (startup), then rc0.d .. rc6.d and init.d all in /etc rather than in /etc/rc.d. Other differences are in handling the networking; Debian has /etc/network/ while RH has different network configuration scripts.

These are all minor differences though (try finding anything on a Mac, which you know came from BSD) and users of one Linux distro can adjust fairly easily.

Otherwise, the tools are really more or less the same between many versions of *NIX and Linux. 'BSD' tends to be the one that's a little weird, but all versions of *NIX have code taken/modified from BSD. The main differences that I find are in your choice of shell and how the shell interprets special characters, performs assignments, etc. You can basically install any shell with the behavior of the shell you want (or close to it - some shells really are unique in a few ways).

Logfiles - similar, though not exactly the same.
Configuration - for many things, similar if not the same.
Programming - ah, well, you run into a lot of differences then, either for historical reasons or just plain different kernel behavior.

Slackware is the most Unix like, as it hasn't changed since it's beginnings. Most people who use BSD will prefer Slackware if they use Linux.

BSD is not Linux and it is actually a Unix, so saying it's Unix like is saying a Ford Mustang is the most Ford like vehicle on a used car lot.

There were some pretty ugly mustangs that Ford might not want to admit were mustangs.

If the purpose is to brush up on Unix, then install any linux distro and run a couple of different BSD flavors and Open Solaris in virtual machines. You'll only find it frustrating to use linux extensively and then have to move to Solaris or other Unix. The reason being, linux is close and a mixture of sysv and bsd, but the commands have subtle differences in command line options.

Well, in my opinion all Mustangs were ugly. That's coming from a Camaro fan though..

To answer your question most Linux users that want more of a UNIX experience use Slackware.

But I must digress for the passer bys that see UNIX vs Linux.

I wanted to do the same thing back in 2002, but how do you get your hands on a copy of AIX? Here is what's available. There are the BSD flavors ie FreeBSD, OpenBSD and NetBSD, which are not Linux and the Linux flavors. In my experience, the BSD's are more of a pure UNIX than Linux. Debian and Slackware are the two most UNIX-like Linux flavors. However, these staements can be perceived as relative. To put it in perspective the local community college teaches UNIX class with an old Red Hat version.

Knowing the Command Line from different shells reveals the *nix world. Study the history and philosophy of UNIX and the programs that evolved into what we use today like VI/VIM, emacs, SED, AWK and perhaps X. Look at the gcc or GNU Compiler collection, since UNIX and Linux are development environments. Look up shell scripting and GNU. Check out books on System V and BSD UNIX from the library.

I used the BSD's, but honestly became frustrated with them, so I moved back to Linux. What I was enjoying about Linux was how the BASH shell and VI were already configured. The C shell and Korn shell aren't the most user friendly. You can use all the different shells in both BSD and Linux.

When your using several commands with piping and redirects you're really starting to utilize the UNIX and UNIX-like environments. Linux does this for me best.

Have fun!

Exactly, using one over the other will get your familiar with each environment. They'll have their differences but in essence, learning the command line from either gets you started and comfortable with both Linux or Unix.

Slackware is the closest I've ever seen -- I work in both Solaris (which is pretty much System V R4 with Berkeley enhancements) and Slackware and, generally, port software back and forth without a lot of fooling around. Too, I work in Korn shell in both and shell programs port directly without change. I find that if I adhere to ANSI/ISO standards for C programming I don't have to change much of anything to go from one to the other and the DBMS' I use (Informix and Oracle) perform identically on both platforms. Slackware's start up scripts are found in /etc/rc.d where Solaris' are found in /etc/init.d and /etc/rc0.d, ..., rcS.d; six of one, half dozen of the other and not real hard to figure out. There are minor -- real minor -- differences in the "standard" utilities, but for the most part you can get along just fine on either platform without a lot of teeth gnashing.

You probably won't go wrong with Slackware.

Hope this helps some.

http://www.oreillyschool.com/

I was considering taking some courses.

has any taken any computer classes here.

I would like to transition to computer programming.