Unix and Linux Stack Exchange
Unix and Linux Stack Exchange

Questions tagged [history]

The history of Unix systems and their main components. Please DO NOT USE this tag for shell-related questions; use "command-history" instead.

This tag is about the history of Unix systems and their main components. For the recall of previous commands in shells and other applications, use .

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

I have often wondered why the ~ (tilde) represents the home directory of a user. Is there a reason behind this, or is it just some infrequently used character?
Lelouch Lamperouge
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459
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5 answers

Why not use "which"? What to use then?

When looking for the path to an executable or checking what would happen if you enter a command name in a Unix shell, there's a plethora of different utilities (which, type, command, whence, where, whereis, whatis, hash, etc). We often hear that…
Stéphane Chazelas
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334
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4 answers

What does "rc" in .bashrc stand for?

Is it "resource configuration", by any chance?
Lazer
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327
votes
5 answers

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 This aptitude does not have Super Cow Powers. and…
derobert
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259
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8 answers

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 seems to be anyone (although you need the root…
Michael Mrozek
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234
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4 answers

Why are tar archive formats switching to xz compression to replace bzip2 and what about gzip?

More and more tar archives use the xz format based on LZMA2 for compression instead of the traditional bzip2(bz2) compression. In fact kernel.org made a late "Good-bye bzip2" announcement, 27th Dec. 2013, indicating kernel sources would from this…
user44370
207
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8 answers

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 of the original? If not, what separates Linux from…
Shawn J. Goff
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138
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6 answers

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 command 1 /usr/bin/whoami [root@c04c ~]#…
spuder
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122
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9 answers

On what systems is //foo/bar different from /foo/bar?

Throughout the POSIX specification, there's provision (1, 2, 3...) to allow implementations to treat a path starting with two / specially. A POSIX application (an application written to the POSIX specification to be portable to all POSIX compliant…
Stéphane Chazelas
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117
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6 answers

If Linux is only a kernel, then how were its first versions used (without distribution)?

Linux is only a kernel, and if users want to use it, then they need a complete distribution. That being said, how were the first versions of Linux used when there were no Linux distributions?
noop
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96
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3 answers

What does the letter 'u' mean in /dev/urandom?

I understand that reads to /dev/random may block, while reading /dev/urandom is guaranteed not to block. Where does the letter u come into this? What does it signify? Userspace? Unblocking? Micro? Update: Based on the initial wording of the…
Tom Hale
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96
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3 answers

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?
Ruban Savvy
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92
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4 answers

Why does Linux use LF as the newline character?

As far as I know, every operating system has a different way to mark the end of line (EOL) character. Commercial operating systems use carriage return for EOL (carriage return and line feed on Windows, carriage return only on Mac). Linux, on the…
Bagas Sanjaya
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83
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6 answers

Why can't Linux usernames begin with numbers?

Is there a technical reason why? Is this an artifact from the early days of Linux or Unix, and if so is there a reason why it persists?
43Tesseracts
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78
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6 answers

What is a socket?

Could someone explain to me what a socket is? I see it in many acronyms in context of SSL, etc. Also, why is it called a socket? Is it purely because it was what a name they invented? Or was it the first name they came up with?
chrisjlee
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