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

learn more… | top users | synonyms

4
votes
2answers
237 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 ...
17
votes
1answer
500 views

What did the sticky bit originally do when applied to files?

In various places one can see the "sticky bit" accused of nowadays being a complete misnomer, as its functionality nowadays is to affect the write permissions on directories and act as a restricted ...
1
vote
0answers
33 views

Is there any history to the shell prompt? [duplicate]

Traditionally, users get the $ prompt and root gets the # prompt but is there any history why this is so?
5
votes
1answer
52 views

Why did “argument can be squished against option” prevail over “argument is always separate”?

Inspired by the recent question Why does the specific sequence of options matter for tar command?, in which the asker learned why tar -cfv test.tar *.jpg doesn't work, I'd like to ask a followup: ...
2
votes
2answers
87 views

Why is $ the default symbol for a user shell and # the default symbol for a root shell?

Operating a standard bash shell on a server, the PS1 prompt defaults to ending in a $ for non-root users, and # for root. IE: ubuntu@server:~$ sudo su root@server:/home/ubuntu# Why is this?
1
vote
2answers
33 views

Autocomplete hostnames when using SSH within history file

I'm looking for a feature that help me to autocomplete the servers I "sshed" in sometime and are in my .bash_history file without messing with known_hosts file or /etc/bash_completition, just grab ...
11
votes
1answer
585 views

What are the differences in shared memory between early and modern Unix systems?

How could processes share memory in early versions of Unix? How does this compare with modern implementations of shared memory?
14
votes
2answers
20k views

What is the concept behind “tty” in linux?

Where did the terminology "tty" come from in Linux?
14
votes
2answers
3k views

Origin of the word cron?

Trying to settle a friendly argument. Is "cron" an acronym for something? Additionally, did it's current canonical name "cron" originate from something shortened for something like chronos or ...
158
votes
3answers
10k 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, ...
3
votes
1answer
58 views

What was the first Unix platform to have the 'yes' command?

I have just answered this question on SO, and it fired off my curiosity a little. So I've searched around but can't find an answer ('yes' is a difficult thing to search for!) There are related ...
4
votes
2answers
36 views

How would I get my terminal to regurgitate the previous output text from past commands? Is this even possible?

I just ran a job that takes several hours, and I forgot to pipe that text into a text file. pseudocode: echo [previous text output] > OutputHistory.txt Additionally, I can't just "copy and ...
6
votes
4answers
172 views

Did all of the Requests for Comments directly affect the design of Unix networks?

I want to know more about Linux must be one of my most enduring sentiments. But I often find that I learn the most, or perhaps just feel the most satisfied with what I have learned, when I simply ...
0
votes
3answers
26 views

Is it possible to tab through the commandline history for a particular command?

For example, can I see all the previous parameters I passed to the command ssh (i.e. all the server addresses I passed as a parameter when calling ssh)? This is going to be something similar to the '...
71
votes
5answers
10k views

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?
9
votes
3answers
843 views

Is it true that the first version of Linux was based on parts of Unix? [duplicate]

Me and a friend had a discussion about Linux and Unix today and my friend kept saying that the first version of the Linux kernel was based on [parts] of the Unix kernel. This really surprised me ...
1
vote
1answer
53 views

What are the oldest irc clients I can still use on linux ?

I have a weakness for nostalgia and some interest in Unix history, therefore I would like to know which are the oldest still usable irc clients that can be run on Linux. In this context I value age ...
1
vote
1answer
41 views

why isn't there a historical pretty log of your upgrades, downgrades and package purges in Debian?

I wanted to lookup history of my recent updates/upgrades, package purges and found out that other than aptitude and ugly dpkg.log, there doesn't seem to be anything else which does the same. See ...
1
vote
0answers
33 views

When was pipelining introduced?

I understand early versions of Unix were licenced from AT&T to Universities and ran on PDP computers. I read in Tanenbaum's book (operating systems) that the first versions of Unix were only a ...
3
votes
1answer
66 views

When did bash's shopt huponexit start defaulting to off?

On Monday morning, I logged into a box with ssh and ran the following command: tail -f /var/log/foo/bar.log | grep something_interesting & At some point later in the day, I logged out by ...
3
votes
3answers
136 views

When was the UNIX single-user vs multi-user modes distinction first introduced?

Practically if not actually every single UNIX-like operating system today makes the distinction between multi-user and single-user modes. Single user mode is generally intended for low-level system ...
51
votes
5answers
5k 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 ...
7
votes
1answer
92 views

What is the historical origin of CTRL + P for up and CTRL + N for down?

I am a moderately experienced vim user, who is now beginning to use GNU emacs. At about the same time as I learned that Ctrl-p and Ctrl-n are the default for up and down in emacs, I also learned they ...
1
vote
2answers
407 views

Why are HTTP operations usually written in all caps? [closed]

I'm looking for the history of this. Why do we usually write HTTP POST or OPTIONS operations in all caps?
6
votes
1answer
444 views

What is ENOANO (No Anode) intended to be used for?

This question is merely for idle curiosity, but I suspect others will be curious as well. Searching through errno.h (of Linux 2.6) I found ENOANO "No Anode". There is no sign of a "No cathode" error. ...
1
vote
4answers
65 views

Why is it find dir -name file and not find -n dir file?

I've searched around for this but I couldn't find anything on it. I've always wanted to know, why is it that most other built in bash commands have the format of command -flag arg1 arg2, i.e. cp -r ...
7
votes
1answer
122 views

Why does 8250 UART driver not wake up TTY if more than 256 characters are pending?

What is the motivation of this if-condition in void serial8250_tx_chars(struct uart_8250_port *up)? if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(port); It has been ...
0
votes
3answers
78 views

Comparing integers: arithmetic expression or conditional expression

In Bash, two integers can be compared using conditional expression arg1 OP arg2 OP is one of ‘-eq’, ‘-ne’, ‘-lt’, ‘-le’, ‘-gt’, or ‘-ge’. These arithmetic binary operators return true if ...
-6
votes
1answer
88 views

Why does GNU say it is “Not Unix”? [closed]

I use Fedora. Today I found GNU (on the web) about which I didn't know till yesterday. I knew that GNU is a Unix-like operating system that is free software but I didn't get why they say GNU's "Not ...
2
votes
3answers
755 views

Why can't Korn Shell do ctrl-r?

If I use PC-BSD with the default shell (Korn) then Ctrl+r doesn't work. Why won't it work? Ctrl-r was introduced to search your history in the late 1970s or early 80s and my BSD still can't do it (...
2
votes
1answer
53 views

Unix vs OS360 (History)

I read the history of Unix operating system and also read the original Unix paper by Thompson and Ritchie. In their paper they mention some key features which Unix uses. Some terminologies including ...
-9
votes
2answers
156 views

What is the name of an animal used as a logo by the GNU Project? [closed]

What is the name of an animal used as a logo by the GNU Project (gnu.org)? And why was this animal chosen to represent the project?
11
votes
1answer
164 views

Why is the circumflex/caret character used as a symbol for Ctrl?

I started using the Linux console a long time ago but I never questioned myself about the circumflex aka caret character (^). I'd like to ask why it's used as a replacement for the word Ctrl. I ...
126
votes
4answers
29k 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. ...
1
vote
1answer
20 views

What was xhbin?

I've googled, searched Unix & Linux Stack Exchange, and... well, there's not really much else I can do, is there? I was browsing some quines in various shell languages, and I came upon the ...
2
votes
1answer
32 views

Behold System V; what about systems I-IV?

System V (by AT&T) is the ancestral Unix, and I have used it. But I have never read or heard anything about systems I-IV, other than they existed once upon a time in the dim past. How effective ...
3
votes
1answer
92 views

Syntactic differences in cp -r and how to overcome them

Let's say we are in a blank directory. Then, the following commands: mkdir dir1 cp -r dir1 dir2 Yield two (blank) directories, dir1 and dir2, where dir2 has been created as a copy of dir1. ...
1
vote
2answers
60 views

Why was shar written if tar already existed?

According to the BSD man pages, tar first appeared in Version 7 UNIX in 1979, but shar first appeared in 4.4BSD, which was released in 1994. What were the perceived advantages to shar at the time? ...
2
votes
0answers
45 views

put string to commandline

I am making a bashfunction that show a menu binded to pgdown to browse through a a window which list my history (like 4dos/4nt etcetera). I have made so one line is always highlighted. $pos is ...
1
vote
1answer
57 views

'revert' bash to searching correct history file [closed]

I hope this makes sense as I explain it, so please bear with me! I recently decided it would be a good idea to start backing up my history, and did so with the following added to .bashrc: export ...
30
votes
6answers
9k 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 ...
33
votes
2answers
2k views

Oldest binary working on Linux?

In a discussion on backwards-compatibility in Linux kernel and GUI ABIs, Alan Cox notes that "my 3.6rc kernel will still run a Rogue binary built in 1992. X is back compatible to apps far older than ...
20
votes
6answers
9k views

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 ...
25
votes
2answers
945 views

Where is “export var=value” not available?

I have picked up -- probably on Usenet in the mid-1990s (!) -- that the construct export var=value is a Bashism, and that the portable expression is var=value export var I have been advocating ...
1
vote
2answers
81 views

Why doesn't unix filesystem store creation time of a file? [duplicate]

Is there any historic reason? Stat stores last accessed time, last modified time and last changed time , but not the creation time! Isn't that important information. I can't understand why the ...
53
votes
5answers
24k 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 ...
1
vote
1answer
57 views

Why is uninterruptible sleep indicated by 'D'?

From "man ps": R = Running or Runnable S = interruptable Sleep T = sTopped Z = Zombie D = uninterruptible sleep (usually IO) Where does this D come from?
31
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.
27
votes
4answers
2k views

Does vi silently add a newline (LF) at the end of file?

I have trouble understanding a weird behavior: vi seems to add a newline (ASCII: LF, as it is a Unix (AIX) system) at the end of the file, when I did NOT specifically type it. I edit the file as such ...
29
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 ...