Questions tagged [unix]

For questions about the Unix operating system.

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6
votes
3answers
870 views

Why does -z and -n exist in most shells and /bin/test?

The test command on Unix-like systems provides two special syntax forms for checking whether a string is empty or not: test -z "$foo" # the length of $foo is zero test -n "$foo" # ...
0
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3answers
1k views

What did developers use before bash? [closed]

It's a fairly short question. How did the early computers before 1989 where bash was published write commands to the OS. Did they have Systemctl?
15
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1answer
459 views

Where and when did the “.s” suffix for assembly-language source files originate?

The closest I was able to find on StackOverflow is What are .S files?, in which no answerer addresses why we use .s for assembly. (And .S for preprocessor/macro assembly; and gcc -S to produce ...
4
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2answers
346 views

Why is the Unix epoch January 1st 1970? (In honor of 1600000000 this weekend.)

In honor of this weekend being 1,600,000,000 (1.6 billion) seconds since the Unix epoch, I was wondering if anyone knows why January 1st 1970 was chosen? According to Wikipedia, The earliest versions ...
28
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6answers
7k 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 ...
10
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2answers
695 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 ...
18
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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 ...
12
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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 ...
5
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3answers
456 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 ...
39
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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?
15
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1answer
240 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 ...
35
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6answers
9k 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 ...
11
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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 ...
14
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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 processes ...
1
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2answers
254 views

Role of Termcap under contemporary unices

A word of caution regarding this question: I'm more a userland than kernel person but have this nagging concern which I think belongs to kernel. When configuring a system one decides on peripherals ...
27
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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 ...
6
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1answer
182 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 ...
5
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1answer
186 views

How to test a chat script with a uucp linux and uucp(server) unix?

I like to play with old networks, uucp is really and advanced(is from the 1978) for that time. I have setup a uucp server in a tru64 unix server. On tru64 server I have edit /etc/inetd.conf uucp ...
12
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0answers
271 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.
13
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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 (...
58
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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, ...
7
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2answers
559 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 ...
11
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1answer
392 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): $ ...
7
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1answer
301 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 ...
24
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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 ...
8
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2answers
605 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?
9
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6answers
982 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 ...
15
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1answer
605 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 ...
4
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1answer
322 views

What was the first publication documenting AT&T syntax assembly language?

What was the first publication to document what is (now) known as AT&T syntax assembly language?
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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?
1
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1answer
265 views

Netscape has detected a /.netscape/lock file

My computer is saying that my netscape file is being used by a host that says it is located in Boulder Colorodo. It is coming from a wierd IP address. I just plugged my ethernet cable to use the ...
49
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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 ...
11
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2answers
642 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, ...
1
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1answer
429 views

How do I compile C code with the IRIX X Window System?

I have typed out a rather large file in C code that is defining OpenGL graphics and will draw a triangle on the screen. While I know all of the functions of the X Windowing System, I do not know how ...
13
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1answer
482 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)....
68
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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 ...
5
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1answer
575 views

On the use of the “Code Improver”

Very early C compilers, (mostly K&R C, as seen in UNIX V6, or this compiler for the Atari ST called "Megamax C") came with a "code improver". This was apparently a separate binary, named c2, and ...
4
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0answers
141 views

a learning gomoku in Lisp

Years ago I played a version of gomoku that was written in Lisp that learned as you played. After a few rounds, it became nearly unbeatable. This was on Unix System III on a small PDP-11. I have ...
60
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3answers
19k 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, ...
16
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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 ...
32
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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 ...
1
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1answer
393 views

File system performance and the Unix API

A 1994 book called 'The Design and Implementation of a Log-structured file system' contains the claim "We have implemented a prototype log-structured file system called Sprite LFS; it outperforms ...
4
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2answers
422 views

Setting up and using UUCP (with analog modems)

These days, of course, we have the Internet, but back in the day, there was Unix to Unix Copy - UUCP. In its heyday it was a terrific way to get email and other simple data moving across the world, ...
13
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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 ...
90
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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 ...
42
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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 (...
4
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2answers
293 views

Could we change the baud rate for the two serial ports on a terminal and on a computer?

Say we have a terminal (for example: VT100) that is connected to a computer (for example: PDP-11), and UNIX V7 is installed on the computer. The terminal will have a serial port that is connected ...
19
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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 ...
21
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3answers
948 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 ...
62
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1answer
10k 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 ...