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

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72
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9answers
5k views
+100

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 ...
4
votes
1answer
46 views

Origin of /etc/termcap linux entry

Why is there a type of $TERM called linux described in /etc/termcap? Why and when was it created and what's the point of it? Couldn't we just stay with vt-generic? Is linux just a customary name and a ...
4
votes
2answers
46 views

Purpose of find command's default size unit 512 bytes

The find command allows you to search by size, which you can specify using units spelled out in the man page: File uses n units of space. The following suffixes can be used: `b' for 512-byte ...
105
votes
6answers
37k 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 ...
35
votes
4answers
4k views

Is the shell ksh93 dead?

On 10/1/2013 Glenn Fowler posted this to the ast-users mailing list: As has been pointed out several times on the AST and UWIN lists, AT&T gives very little support to OpenSouce software, ...
0
votes
0answers
16 views

Save history to separate file with time-stamp and who did the action

I'm looking for a solution to capture all Linux commands to some file, there are many solutions but I prefer to capture all History to some file. I want it to include : "time-stamp" "Server-name" ...
3
votes
1answer
88 views

History of UNIX not including current directory in $PATH

In the UNIX world, it's well understood that you need to prefix binaries in the current directory with ./ in order to run them: . is not in $PATH by default. This is to avoid evil binaries overriding ...
174
votes
5answers
26k 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 ...
0
votes
4answers
122 views

How to run Unix?

I always wanted to try Unix but I can't seem to find an ISO file or somewhere to buy it. Is Unix published for the whole wide world to use or is it a special OS only for high-class servers, mainframes ...
623
votes
2answers
128k views

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?
11
votes
2answers
589 views

Is there a reason why the first element of a Zsh array is indexed by 1 instead of 0?

From my experience with modern programming and scripting languages, I believe most programmers are generally accustomed to referring to the first element of an array by 0 as index. Are there any ...
48
votes
6answers
3k views

Is there any reason to have a shebang pointing at /bin/sh rather than /bin/bash?

In most shell scripts I've seen (besides ones I haven't written myself), I noticed that the shebang is set to #!/bin/sh. This doesn't really surprise me on older scripts, but it's there on fairly new ...
4
votes
1answer
761 views

What does the “f” in fdisk stand for?

gdisk stands for GPT fdisk. cfdisk stands for curses fdisk. And so on and so forth. However, what does the original "f" in fdisk stand for? The only things I can think of would be either "files" or ...
126
votes
6answers
42k 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 ...
0
votes
1answer
69 views

What can be considered as operating system? [closed]

I am talking about GNU/Linux but not about GNU or Linux! I know that Kernel is the core component in operating system but I want to know what defines the "operating system" (What can be considered as ...
80
votes
3answers
14k 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?
15
votes
2answers
10k views

Is `cal` broken? What happened in September 1752?

If you look at the output of cal 9 1752 you will see this strange output: September 1752 S M Tu W Th F S 1 2 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 The following story ...
0
votes
1answer
82 views

What really is bash? (or any linux shell) [duplicate]

I understand bash as a window where I can type commands to linux. Reading the wikipedia, I've learned that there were various shell applications throughout the history. First, I understood bash as ...
4
votes
1answer
70 views

Why does a '.' work in chown?

Why does GNU chown user.group work? The docs say nothing of the syntax being supported. Is there a juicy story behind it?
21
votes
2answers
2k views

Origin of 'root' account

What's the origin of root account? Where did it come from and why is it called root anyway? (Originally asked by @lizztheblizz on Twitter.)
2
votes
1answer
62 views

Why do GNU tools use non-matching ` and ' to quote errors?

GNU tools often output error and warning messages with parts of the line (e.g. filenames, syntax errors, invalid dates, etc) quoted with non-matching quotes: ` and ' e.g. From the GNU coreutils FAQ: ...
2
votes
2answers
98 views

Was 'diff' included in the first version of Linux

What is the list of programs that were available in the first public version of Linux distribution (not just kernel)? I am specially concerned when this distribution was released and if diff utility ...
1
vote
1answer
97 views

Why does xargs -I imply -L 1

I've seen Why does 'find -exec cmd {} +' need to end in '{} +'? which explains why {} + has to be at the end of the -exec cmd(*), and now I'd like to know why GNU xargs reverts to one ...
3
votes
3answers
129 views

Why is NetworkManager package name upper case?

All other software packages are lower case, so why NetworkManager upper case?
1
vote
1answer
47 views

Relation between emacs and bash terminal shortcuts [closed]

I would like to know what is the relation between emacs and bash terminal shortcuts.
1
vote
1answer
41 views

Zeller's congruence and cal command

According to Zeller's Congruence, the day of 29 Feb, 1600 is Tuesday. However, the cal command shows it as Friday.Is there a bug in cal's code or a limit on the range of years which Zeller's ...
139
votes
3answers
9k 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, ...
28
votes
5answers
2k views

What is the point of mv -f

The GNU Coreutils manual for mv says: -f --force Do not prompt the user before removing a destination file. However, this already seems to be the default behaviour for mv, so the -f option appears ...
50
votes
5answers
18k 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 ...
18
votes
3answers
823 views

The Linux kernel: breaking user space

I started thinking about this issue in the context of etiquette on the Linux Kernel Mailing list. As the world's best known and arguably most successful and important free software project, the Linux ...
2
votes
0answers
38 views

What is the background of the program segmentation?

Each program is separated into several segments like: code segment data segment stack segment heap segment But who was responsible for that progression? The compiler and linker has to support that ...
36
votes
4answers
9k views

What did Ken Thompson mean when he said, “I'd spell creat 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 creat with an 'e'." What is Ken referring to? Is there a "creat" command?
27
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.
1
vote
0answers
21 views

Etymology of “descriptor” in “file descriptor”

The choice of the word descriptor has always struct me as odd. "Index" or "id" seem like more obvious alternatives. Is there a known rationale for the choosing the word "descriptor"? I guess ...
18
votes
2answers
376 views

Why does niceness range from -20 to 19?

The nice command allows you to adjust the scheduling priority ("niceness") of a program. On all Unix-like systems I've used, niceness is specified by a range of integers, where -20 is the most ...
51
votes
5answers
4k views

Why does no one use the true Bourne shell as /bin/sh?

I've noticed that basically no system I've ever worked with has /bin/sh as a real executable. It's always a symlink to dash, bash in POSIX mode, or something similar. Why? What are the disadvantages ...
1
vote
1answer
117 views

Where did the default GTK2 theme (raleigh) theme come from?

Who made the theme? When was the theme made? Was it made originally for a specific distro? Does the theme have anything to do with the city of Raleigh?
4
votes
3answers
141 views

Historically why is umask the way it is?

umask has always tripped me up. Logically I would prefer to have a 'setmask' instead that takes chmod-style arguments. Anyone know why it is the way it is?
139
votes
3answers
25k views

What does “rc” in .bashrc stand for?

Is it "resource configuration", by any chance?
2
votes
0answers
38 views

Where does the name of i3 (the WM) come from?

I was thinking about this, so I searched the i3 website, but did not find anything. I was alarmed by the thought, that the name was ie (internet explorer) in leetspeak. It might also be a weird ...
45
votes
2answers
4k views

why is rm allowed to delete a file under ownership of a different user?

From the post Why can rm remove read-only files? I understand that rm just needs write permission on directory to remove the file. But I find it hard to digest the behaviour where we can easily delete ...
0
votes
2answers
797 views

Where does the word GNU come from?

GNU is a Unix-like operating system. That means it is a collection of many programs: applications, libraries, developer tools, even games. The development of GNU, started in January 1984, is known ...
1
vote
1answer
265 views

How can I find out the IP address from which a user logged in?

We have two RHEL 6.4 64-bit boxes in our environment. They are accessed remotely via putty. The password of user ABC on one RHEL box is shared by multiple users. User ABC logged into server from ...
2
votes
1answer
60 views

What is the meaning of the mode mask names from stat(2) and chmod(2)?

The stat calls have a series of symbolic names for the various bits in the mode field. From the stat(2) manual page: The following mask values are defined for the file mode component of the st_mode ...
2
votes
1answer
1k views

Why is the Intel HD Graphics driver called i915?

The only references to i915 I can find are indeed to the linux kernel driver for the intel chips. Intel just seems to call them HD graphics whatever. Intel 915 seems to refer to some Pentium 4 ...
7
votes
1answer
224 views

How were these Linux TCP default settings decided?

I spent quite some time tracking down a problem in production recently, where a database server disappearing would cause a hang of up to 2 hours (long wait for a poll() call in the libpq client ...
2
votes
2answers
73 views

Why are certain naming conventions so inconsistent in Linux? [closed]

It seems like the general pool of logging, changelog, readme, and config files in Linux is very inconsistently named. It always makes me wonder, why didn't *nix devs decide on a common file name ...
111
votes
3answers
24k views

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. ...
18
votes
2answers
3k views

Why is JFS so obscure?

When I first got into using Slackware years ago I quickly learned to love JFS over ext3 or reiserfs given that it was reliable and if there was an unclean shutdown, its disk checking was very very ...
10
votes
3answers
748 views

Why does the “she-bang” begin with a “#!”?

Why does the "she-bang" begin with a #!, like #!/bin/bash? I have always accepted that this how it is done, but is there a reason behind it? Why start with #; isn't that usually a comment? Or is it ...