Think different. Think very different! No, you're not thinking different enough! Think so differently that thinking becomes not-thinking and different is different from different! Until your mind becomes no-mind and your thoughts are un-thoughts! Astrally project your self into space, beyond the reaches of the galaxy where time is not time...
Sorry, got carried away. Just wanted to get you in the mood. Welcome to Plan 9 from Bell Labs - the weirdest operating system ever conceived! Visitors checking out my past three entries reviewing Belenix, GNU/HURD, and FreeSBIE, might have cause to wonder what was keeping me from experiencing those systems fully and why I reported such struggles with learning them. That's because I was fooling with plan9 the whole time in the background - which was burning every spare cycle I have.
Let me lay a big card on the table right now: I would not recommend this system as your day-to-day OS. Not even! But, as is frequently pointed out, it makes an amusing toy. Oh, yeah! If you're a hobbyist geek, you can give yourself a nice present by downloading the live CD (which also installs!) and keeping it around. How would I describe plan9 in a word? CUTE!!!
plan9 is not Unix, is not DOS, is not Mac. It exists in its own sphere. Its shell is rc. Its window manager is rio. Its file manager is acme. Its editor is sam. It has about 30% of the commands familiar from the Unix/Linux console world, and some behavior in common with Unix, but there the similarities end. The documentation goes on extensively about how they set out to throw out all preconceived notions of what an operating system is and start *clean*. And they made considerable efforts to change everything, even (it could be argued) in places where the old way was good.
The learning curve was absolutely vertical. I had to start over from scratch learning how to give commands, how to run programs, how to mount writable media, how to display pictures and play games and read man pages and HTML files, how to copy and paste. Copy and paste is actually "snarf and paste" though I would recommend that if you change "copy" to "snarf", you should follow suit and change "paste" to "barf".
Nevertheless, plan9 pulled me in like a tornado. Its interface is very tasteful. The color scheme is soft and gentle. The window manager is efficient. The fonts are adorable. The mascot "Glenda" is huggable. Every time I look at it, I think of the "Miffy and Friends" TV show theme song: "Miffy! Cute little bunny! Miffy! Smart little bunny!" plan9 can do truly crazy tricks, such as:
You can type or edit text *anywhere* there's a screen. You can literally type a command in midair in acme and then middle-click to execute it. You can type your file in the middle of the man page you're viewing and save it. You make a screen shot not with a special utility, but merely by piping /dev/screen to a file. There is no menu with executable programs; you type everything in a terminal window, which will then take off and morph into whatever program you told it to be. You generally work with one hand on the mouse and one on the keyboard; and your mouse had *better* have three-button functionality or you're out of luck. There is no special viewer that has to run for man pages or html files; instead, the printed text is simply dumped out to your screen, and you scroll out of it to get back to a terminal command prompt. You can run the rio window manager inside of a window running in rio...as many nested instances as you want! It takes some time for computing habits to return to normal when using other operating systems after running plan9 for a while.
plan9 has lots of downsides. The console is missing tab completion and up-arrow command recall. Thus, if you type out a command string and blow it, your only choice rather than hitting up-arrow and fixing your previous typo is to highlight the previous command line with the mouse, middle-click to snarf, click back to your current prompt, middle-click to paste...this put me off. Another bone to pick is, once you have a file system mounted and accessing a file and you then start a new program, you have to mount it *again* to access the same system...mounted systems apply only to that window in which they were mounted. This means that when you're done playing with everything, you then have to be careful to *unmount* (yes, they put the 'n' back in!) each individual instance, or you hose things up.
Other downsides are the obvious: it's virtually unknown to the world, so docs are scanty and support is seldom. There is a small nest of developers porting applications to it ( some really unexpected ones, like Firefox, Xaos, and POVray ), but not anywhere near the same as for Linux/BSD, or even Solaris. It has been around for a while, slowly being built, but seems to not have a user/developer community so much as it has a cult. Yes, a cult following! It lacks appeal for 95% of the world, but it's cream to the weirdo 5%.
And it has my attention! If it only caught on, it could kick ass! plan9 shows us another world that could have been, almost like what computers would be like in an alternate dimension. It is fascinating, and worth the time just for the curiosity value. Besides, programs for it can still be written in plain ol' everyday C, and it runs Perl and Python! How difficult to adapt could it be???
UPDATE 7/23/06: For those of you just joining us from places like Slashdot or OSNews (after a couple of hops): I reviewed this from the point of view of a Linux user experimenting with other free and open operating systems; part of a grand tour that included BSD, Solaris, and GNU/HURD. I openly admitted that I was struggling to learn it in three days or so while I was blogging this little tour. I think I made it clear that I genuinely *like* plan9.