The history of Unix systems and their main components.

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79
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3answers
5k views

Why not use “which”? What to use then?

When looking for the path to an executable or checking what would happen would you enter a command name in a Unix shell, there's a plethora of different utilities (which, type, command, whence, where, ...
90
votes
5answers
21k views

Is Linux a Unix?

So, there are lots of different versions of Unix out there: HP-UX, AIX, BSD, etc. Linux is considered a Unix clone rather than an implementation of Unix. Are all the "real" Unices actual descendants ...
10
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4answers
3k views

Evolution of Operating systems from Unix

Can you explain the evolution hierarchy of operating systems (Linux and Windows) from Unix?
21
votes
4answers
3k views

Single dashes `-` for single-character options, but double dashes `--` for words?

Where did the convention of using single dashes for letters and doubles dashes for words come from and why is continued to be used? For example if I type in ls --help, you see: -a, --all ...
27
votes
5answers
5k views

Why do /usr and /tmp directories for Linux miss vowels in their spellings?

I have often started to think about this but never found a good answer. Why are these two Unix directories not /user and /temp instead? All the other directories under root seem to be exactly what ...
80
votes
6answers
23k views

Where did the “wheel” group get its name?

The wheel group on *nix computers typically refers to the group with some sort of root-like access. I've heard that on some *nixes it's the group of users with the right to run su, but on Linux that ...
36
votes
5answers
3k views

Why is there a * When There is Mention of Unix Throughout the Internet?

I've noticed that throughout the Internet, within forums and blog posts, Unix always has a * in the word, whether it is *nix or Un*x, as I noticed at the welcoming banner at the Unix StackExchange ...
513
votes
2answers
119k views

Why was '~' chosen to represent the home directory?

I have often wondered why the ~ represents the home directory of a user. Is there a reason behind this, or is it just some infrequently used character?
91
votes
3answers
13k views

What does “rc” in .bashrc stand for?

Is it "resource configuration", by any chance?
24
votes
1answer
2k views

Were all Unix commands re-written in Linux?

I would like to know which commands were re-written for Linux and which were retained from Unix? I'm new to Linux.
16
votes
2answers
1k views

What is Unix now?

As I read in Wikipedia, Unix started as a revolutionary operating system written mostly in C allowing it to be ported and used on different hardware. Descendants of Unix is mentioned next, mostly BSD. ...
20
votes
2answers
995 views

Why do Unix man pages use double backticks in place of double quotes?

I've noticed that man pages and other documents formatted by Unix utilities often use double backticks `` followed by double single quotes '' to wrap quoted phrases instead of the double quote ...
24
votes
4answers
2k views

What is GNU Info for?

I understand what GNU Info is and how to use it, but what is it for? Why does it exist in parallel to the man pages? Why not write detailed man pages rather than provide a separate utility?
28
votes
3answers
6k views

What did Ken Thompson mean when he said, “I'd spell create with an 'e'.”

Ken Thompson, the creator of Unix, was once asked what he'd do if he had it to do over again. He said, "I'd spell create with an 'e'." What is Ken referring to? Is there a "creat" command?
4
votes
2answers
232 views

What are all the items on the cover of the “Linux Administration Handbook”?

As I mentioned in What do all the pictures on the front of the "Unix and Linux System Administration Handbook" represent? I'm fairly new to Linux and Unix. @jasonwryan provided an excellent ...
124
votes
5answers
12k views

What's the story behind Super Cow Powers?

As we know, apt-get has Super Cow Powers and aptitude does not: $ apt-get --help | grep -i cow This APT has Super Cow Powers. $ aptitude --help | grep -i cow ...
72
votes
3answers
10k views

Why is the root directory denoted by a / sign?

I have done some research about this on Google, but the results were cloudy. Why is the / sign used to denote the root directory. Are there any solid reasons behind it?
27
votes
3answers
4k views

What is the purpose of the hash command?

If you run hash it shows the path of all commands run since the hash was last reset (hash -r) [root@c04c ~]# hash hash: hash table empty [root@c04c ~]# whoami root [root@c04c ~]# hash hits ...
36
votes
2answers
7k views

Why is 'umount' not spelled 'unmount'?

I am wondering if there is any historical or practical reason why the umount command is not unmount.
12
votes
2answers
2k views

What are the main differences between BSD- and linux-based operating systems?

I am a long time linux user and have recently become interested in playing about with BSD-based operating systems. What are the differences between linux and BSD-based systems. I am interested in ...
20
votes
1answer
1k views

What does Ritchie's 1979 PDP-11 `/usr/games/bcd` do?

I recently tried the simh emulator pdp11. The disk image I used can be found on the internet, and instructions for booting it are here. Presumably it belonged to Dennis Ritchie, as the username is ...
11
votes
1answer
726 views

What do all the pictures on the front of the “Unix and Linux System Administration Handbook” represent? [duplicate]

I'm a newcomer to Unix and Linux, and I've been trying to get up to speed on everything. One of the guides I've used is the "Unix and Linux System Administration Handbook" It's a pretty great book, ...
20
votes
3answers
8k views

Why does Unix time start at 1970-01-01

Why does Unix time start at 1970-01-01? Why not 1971-01-01 or any other date?
10
votes
2answers
412 views

/usr/bin/ptx: Can you provide a use case or two?

I was going through the list of files included in coreutils and I was able to come up with an example of how I could personally use all of the commands provided except for ptx. Can you give one or two ...
4
votes
5answers
769 views

If Mac OS X is UNIX, why is it that it is not open sourced and the license is proprietary?

If Mac OS X is a Unix, as answered in this question, why is it that it is not open sourced and the license is proprietary, as stated in this Wikipedia article? According the the genealogy from this ...
3
votes
1answer
137 views

What does it mean when something says that UNIX device files are static?

I've been reading up on udev. In the "overview" section, Wikipedia states that "unlike traditional Unix systems, where the device nodes in the /dev directory have been a static set of files, the Linux ...
7
votes
3answers
259 views

When was process substitution first introduced?

I'm curios to know how long process substitution has been around. What shell first had it? When did it get added to other shells?
6
votes
1answer
172 views

Where does this convention for quotation marks (`` …'') come from? [closed]

Frequently I get asked the question: ``K., where does this convention for quotation marks come from? You know, the one with the two grave accents introducing a quoted string and two regular ...
2
votes
4answers
245 views

Is the Filesystem Hierarchy Standard a UNIX standard or a GNU/Linux standard?

The Filesystem Hierarchy Standard says where to put stuff in a UNIX distribution. Is the FHS used/designed for use outside of GNU/Linux, or is it mostly limited to GNU/Linux?
2
votes
3answers
129 views

Why are POSIX Find Parameters Different from Other Program styles?

Why is a parameter in the POSIX find command added with a single hyphen for multi-character parameter names, while most other programs use single hyphen to indicate multiple single-character flags, ...
1
vote
0answers
57 views

Where does backtick and single quote come from when denoting commands e.g. `prog'? [duplicate]

When referring to commands in tutorials, man pages, and articles I see authors use the backtick and single quote in this way: `./configure' `make' I believe I have seen gcc denote points of failure ...
1
vote
2answers
1k views

Who wrote the “Linux kernel” (Linus Torvalds and his team)?

Who are the authors of the pure Linux kernel from scratch, which was integrated with GNU tools and formed the full GNU/Linux Operating system in the 1990s? I have read some wiki articles but I haven't ...