Questions tagged [unix]

For questions about the Unix operating system.

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90
votes
19answers
18k views

How did people use ed?

ed was the standard Unix editor, and is present on all POSIX certified systems (though it's not installed by default in Debian, FWIW). It's a line editor (meaning, you can't see all the text at a ...
68
votes
3answers
8k views

Why did Unix use slash as the directory separator?

The Unix designers came from the GE/MIT Multics project, and Multics inspired some Unix features. In particular, Multics has a hierarchical filesystem, and so does Unix. On Multics, pathnames were of ...
61
votes
1answer
9k views

What's the story behind the name “X11”?

To this day on Linux configs and startup scripts for the GUI system are stored in /etc/X11. I remember this name appearing alone, or alongside others - XFree86, X.org, X - for as long as I had contact ...
58
votes
1answer
10k views

When was the famous “sudo warning” introduced? Under what background? By whom?

On all Unix-like operating systems, sudo is often provided as the standard package for executing commands as superuser (or an alternative user). When sudo is invoked by the user for the first time, ...
57
votes
2answers
17k views

Why is Windows using CRLF and Unix just LF when Unix is the older system?

Windows and MS-DOS use for new lines the control characters CR-LF (carriage return, line feed), while unix uses just LF. As far as I know CR-LF made sense for systems controlling an real teletyper, ...
55
votes
5answers
13k views

Which Linux or BSD distributions do still support i386, i486 or i586 CPUs?

Unfortunately Debian kicked out Pentium 1 (i586) CPU support from its 32-bit PC port (named i386 for historic circumstances) for its next stable release Debian 9 Stretch. (Then again they complain ...
52
votes
5answers
12k views

Why did base64 win against uuencode?

From the the two methods of encoding 8-bit data as human-readable ASCII, for a time, uuencode format was more popular. USENET 'binaries' groups were filled with uuencoded posts with whatever goodies ...
49
votes
10answers
9k views

Why was preemptive multitasking so slow in coming to consumer OS's?

Preemptive (rather than cooperative) multitasking was a highly-touted feature for PC's in 1996, with its inclusion in Windows 95 for the first time. It was also highly-touted for 2001 Macs when ...
41
votes
2answers
23k views

Why were the /\ (min) and the \/ (max) operators abandoned in the C language?

In the UNIX V7 version of the C language (but not yet in the V6 version), there were the /\ (min) and the \/ (max) operators. In the source of the scanner part of the compiler, case BSLASH: if (...
39
votes
1answer
7k views

What warning was given on attempting to post to USENET, circa 1990?

I recall a confirmation/warning message that read something like "this will post to thousands of sites... are you sure?" What was a typical such message in the days of pay-per-minute dialup access?
34
votes
6answers
8k views

How should we interpret Dave Cutler's criticism of Unix?

Dave Cutler is well known for his contributions to operating systems, having led the effort on VAX VMS at DEC and Windows NT at Microsoft. According to his Wikipedia page, he is also known for ...
32
votes
2answers
5k views

Why was UNIX never backported to the PDP-7?

Originally, UNIX was written in PDP-7 assembly, and then in PDP-11 assembly, but then when UNIX V4 began to be re-written in C in 1973 and was run mostly on the PDP-11. So far as I can tell, there ...
27
votes
6answers
3k views

Why does UNIX ed not have a prompt by default

The line editor ed in UNIX/Linux has a "command mode" and an "insert mode" and there is no visual way to tell which mode you are in. However, there is a -p option that causes it to display a prompt ...
27
votes
6answers
6k views

What are the major technical difference between Multics and Unix?

From the naming of operating system only i.e Unix = Uniplexed Information and Computing Service vs Multics = Multiplexed Information and Computing Service, I was first having a misconception that the ...
24
votes
4answers
5k views

Was Unix ever a single-user OS?

I've been told that Unix started out as a Phone Switch OS and was not a multi-user OS at some time in its infancy. As I'm always willing to learn new things, are there any greybeards around here ...
21
votes
1answer
2k views

Process model in early UNIX

I heard recently that the process model in very early variants of UNIX was quite a bit different to the fork/exec model used nowadays. How did it differ from the current state?
20
votes
3answers
896 views

What software stack could I use to get X10 (the version of X before X11) up and running on a modern system?

"What's the story behind the name "X11"?" showed up in the sidebar while I was browsing stackoverflow earlier and I noticed the question getting some high-signal answers, so I added a ...
19
votes
2answers
1k views

Slash versus backslash as directory separator - what/who caused this rift?

MS DOS and derived systems use backslash \ for path separator and slash '/' for command parameters. Unix and a number of other systems used slash '/' for paths and backslash \ for escaping special ...
18
votes
1answer
2k views

Identifying late 1990s embedded 486 UNIX-like system

I'm trying to identify the operating system on a Thermo-CRS C500 robot arm controller. From the specifications I know it runs on a 100 MHz 486 processor, and has 4 MB RAM and 2MB of flash/NVRAM ...
16
votes
5answers
3k views

What determines which architecture an a.out executable runs on?

The ELF file format has an e_machine field in the header, which specifies which ISA the executable expects. And the e_ident structure also has an EI_OSABI field that specifies which ABI the executable ...
15
votes
1answer
582 views

Why does AT&T syntax use * and $?

In a comment to an answer about AT&T assembly syntax, another-dave asked the following: DEC used #foo for an immediate operand in -11 assemblers; the Unix guys apparently preferred $foo, which ...
13
votes
2answers
3k views

Could you use uppercase or special characters in a password in early Unix?

This article is about Ken Thompson's old Unix password hash being cracked. One line in the article intrigues: "Even an exhaustive search over all lower-case letters and digits took several days (...
13
votes
6answers
3k views

Using only one terminal, can I interrupt a process that's hung on very early Unix versions?

Within modern shells, I am able to leave a process via one of two control sequences: Usually Ctrl + C will directly send SIGINT to the majority of shell commands (e.g. ping, echo, cat) A few ...
13
votes
1answer
3k views

How many lines of code were in the first Unix version (with the Thompson shell)?

How many lines of code were in the first Unix version (with the Thompson shell)? Given that the modern Linux kernel has about 15 million lines of code, I do wonder of the amount with the first Unix ...
13
votes
1answer
468 views

Where did /usr/mdec come from?

On UNIX, the boot code is traditionally found in the directory /usr/mdec. Some modern UNIX variants keep this tradition up (e.g. OpenBSD) while others have changed the directory layout (e.g. FreeBSD)....
13
votes
2answers
981 views

How can I build Gameboy Development Kit 2.1.5 on a modern Unix/Mac platform?

Continuing with my quest to build the Infinity Game Boy Color source code, I am trying to build the Unix source of GBDK 2.1.5 on my macOS El Capitan machine. Trying to make the files in the lib ...
12
votes
2answers
3k views

How did the /dev file system work in early Unix?

UNIX did not have support for virtual file systems (vnodes) until 1986. S.R. Kleiman, “Vnodes: An Architecture for Multiple File System Types in Sun UNIX,” Summer USENIX 1986 I remember this quite ...
12
votes
0answers
253 views

Unix on the H11?

I'm curious if anyone is aware of actual uses of Unix on the Heathkit H11? I don't see any technical reason a memory-expanded H11 couldn't run Unix, but can't find any examples of it doing so.
11
votes
4answers
1k views

Is it a Directory, a List, or a Catalogue?

There are three common CLI commands on microcomputers that all mean the same thing: "Show me the contents of a volume, disk, or sub-directory". I will mention that the noun "Catalogue", and the ...
11
votes
2answers
1k views

What is the version of Unix and the name of the computer it run on in this 1982 video?

I am learning about the history of computers, and based on what I know so far, Unix was run on a large computer, and in order to use it, you have to use a computer terminal. Does anybody knows what ...
11
votes
2answers
621 views

Origin of “tarball”

It seems to be common (at least among my section of the world's *NIX users) to refer to "tape archives" made with GNU tar or similar as "tarballs". I always thought this was a slightly odd choice, ...
11
votes
1answer
381 views

Unix utility “smiley” to decode emoticons: Where to get it?

I remember in the 90s, there existed a Unix command line utility named smiley that decoded emoticons. A sample use would be like this (the output is likely not the exact output the program gave): $ ...
10
votes
2answers
564 views

Trying to understand some assembly syntax in the Unix v7 write system call

so here is the code: (which comes from here, I've also verified this source is in my unix v7 distribution). For reference, this is running on a PDP-11 simulated with the simh program (so please keep ...
10
votes
1answer
556 views

How POSIX-compliant is Xenix?

Xenix was the most popular Unix flavour of the 80's. However, it was designed before the POSIX standards came to be, and its final version was released shortly after the first POSIX specification was ...
9
votes
6answers
879 views

What happens when a terminal (like a VT100) is connected to a computer?

I'm wondering what's the sequence of actions when a terminal (like a VT100) is plugged into a serial port of a computer? Especially, how the connection of this terminal is detected, and how the ...
8
votes
2answers
459 views

Is there anything special about /dev/console?

I am using the SimH emulator to emulate a PDP-11 computer with UNIX V7 installed on it. So basically I am emulating something like this: I issued the tty command to see on which TTY port my terminal ...
8
votes
2answers
585 views

Does “Unix” and “UNIX” represent the same thing?

In some articles I see the word Unix written as "Unix", while in other articles I see the word Unix written as "UNIX". Does "Unix" and "UNIX" represent the same thing?
8
votes
3answers
624 views

Was The Telemark Assembler available for the Unix or Mac Environments?

I'm trying to build the recently released Infinity Game Boy Color source code on my macOS El Capitan box. The original development environment was a Windows box, and I'm trying to modify the build ...
8
votes
0answers
135 views

What proprietary AT&T code/features were removed in BSD Net1 (/2), and BSD 4.4 Lite (/2) from the original 4.3BSD codebase?

Background Although BSD and its source code was freely available under the original BSD licenses, but it only covered the portion of the code which copyright was owned by Regents of the University of ...
7
votes
2answers
633 views

Does ancient UNIX create a new shell process for each terminal?

In Linux, each terminal is associated with a new shell process. For example, here I have two xterm terminals, and each xterm terminal has an associated shell process: I am wondering if in the old ...
7
votes
2answers
544 views

How to setup a teletype to a unix shell

So, recently I've been researching old tech because I want to write some fiction about some typewriter that can access the command line(yep) that shows up in many youtube videos like This one. I want ...
7
votes
1answer
288 views

WEGA operating system origins

I just recently stumbled across information about DDR minicomputer P8000 and its unixoid operating system WEGA. The website above as well as Wikipedia seem to claim some compatibility or even ...
7
votes
1answer
356 views

“ps” returning “No namelist” on UNIX V7

I am using this emulator for UNIX V7: http://www.jbox.dk/sanos/pdp11.htm When I type ps to get a list of processes, I get the following error:
7
votes
1answer
290 views

How to get a list of processes on UNIX V7?

I am running UNIX V7 using the SimH emulator. I am trying to get a list of processes using ps, but I am getting the following error: No namelist So I tried the following fix (from this post): cd /...
6
votes
2answers
207 views

Is the terminal number fixed?

Let's say that we have a PDP-11 computer with Unix installed on it and we have three terminals connected to it: A terminal can use the tty Unix command to get the terminal number. Now my question is:...
6
votes
1answer
424 views

Can you get the file descriptors of a process in UNIX V7?

In Linux, if I want to get the file descriptors of a process, I would go to the following directory: /proc/<pid>/fd But in UNIX V7, the /proc directory does not exist.
6
votes
1answer
148 views

Does the TELCOM program on the Tandy Model 100 support any Unix terminal–like control codes?

I've been connecting my Tandy Model 100 to a serial port on a Linux box via the TELCOM program with some success. The main downside is that in whatever the default terminfo/$TERM setting it gets, a ...
6
votes
1answer
226 views

Was job control supported in UNIX V7 or earlier?

Linux supports job control, i.e. you can start a process in the background, or make a foreground process run in the background, or make a background process run in the foreground, etc. Did any V7 or ...
6
votes
3answers
1k views

Is the SimH emulator available on macOS?

Is the SimH emulator available for macOS? I can't find it on their website: http://simh.trailing-edge.com/ What I am specifically interested in is to run UNIX V7 on a PDP-11 emulator.
5
votes
3answers
398 views

What were the Major Public Access Unix Systems Available in the 1980s-90s?

Back in the 1980s-90s, using a UNIX system required running expensive servers or paying for timesharing service, so they were beyond the reach of most individuals, and only available to members in ...