Questions tagged [unix]

For questions about the Unix operating system.

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Early implementations of the `system()` call in a consumer OS

Nowadays, it's easy to take for granted the system() call (as defined in POSIX), which allows a user program to easily execute a child process and wait for it to complete. Obviously, this is a trivial ...
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4 votes
1 answer
318 views

Why did Dennis Ritchie write that UNIX was a modern implementation of CTSS? [closed]

At the Tenth Hawaii International Conference on the System Sciences in 1977 Dennis Ritchie presented the paper The Unix Time-sharing System: A retrospective in which he states: ...a good case can be ...
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30 votes
2 answers
7k views

Correct pronunciation of `vi` (Unix editor)?

According to this video with Brian Kernighan, the correct pronunciation of the classical Unix editor ed is "Eee. Dee." — not "Edd". So that made me wonder — what about the other ...
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7 votes
0 answers
218 views

Small format X terminal with EL screen

I remember an ad for a small-format (about as wide as a 60% keyboard) dark-ish grey colored X terminal that had a 12" (?) yellow electroluminescent screen similar to the Grid laptops but higher ...
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10 votes
1 answer
525 views

Nontrivial B program

I have been able to find very little about the B programming language online. the predominant resources seem incomplete, particularly in regards to standard library functions. I have not been able ...
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25 votes
9 answers
4k views

What happened to all those Unix workstations in the '90s?

Around the early to mid '90s it seems there was a trend for high-end workstations running some form of Unix, and running a RISC or at least some kind of non-x86 architecture. For example: Sun ...
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4 votes
1 answer
547 views

Why did this joke man page use July 16, 1974 as an epoch?

This fake manual page posted to the comp.humor newsgroup jokes that A.out accepts any option passed to it, stalls for a few seconds, and then prints a cryptic message chosen from the list below. The ...
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9 votes
2 answers
348 views

What environment was Coherent developed with?

Coherent was a Unix clone for IBM compatibles Mark Williams Company produced and sold in the 1980s and early 1990s. What environment and tools was Coherent developed with? Was it cross-developed on ...
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4 votes
1 answer
150 views

When did an overlay linker first appear in a PDP-11 UNIX OS?

On a 16-bit system with at most 64K of RAM available for a user program, one would think of having an executable overlay mechanism as an indispensable tool to maximize the amount of memory available ...
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11 votes
1 answer
615 views

How did early Minix represent processes

Minix, as most know, is a "Unix-like" OS originally used for teaching. Early Minix (v1 and, apparently, v2) ran on the 8088/6 series of processors. It could run on the IBM XT. There have ...
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17 votes
3 answers
4k views

What is the simplest UNIX system with a MMU?

I was recently looking at a Motorola 68010 and 68451 that have been in some ESD foam on a shelf for a very, very long time. Now, things are all so huge in memory, but BSD4.4-Lite can run in only 256k ...
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2 votes
2 answers
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How did Unix handle multiprocessing when virtual memory didn't exist?

It seems the first "real" virtual memory management system was the i386 with its powerful paging system that totally isolates processes. How did Unix work before this, ensuring no process ...
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8 votes
2 answers
2k views

What are the "other crontabs" that /etc/crontab refer to? [closed]

The /etc/crontab file on ubuntu has a header that reads: # /etc/crontab: system-wide crontab # Unlike any other crontab you don't have to run the `crontab' # command to install the new version when ...
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15 votes
1 answer
2k views

How would old software using the SIGPIPE signal really work if it were to manage _many_ pipes?

I'm wondering what was the thinking behind having a SIGPIPE signal. From my own experience, the first thing I do is turn off that signal (SIGIGN) and use the return value of the calls to make sure it ...
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36 votes
3 answers
4k views

Why does make only accept tab-indentation?

The syntax for Makefiles requires that indented lines start with a tab, and not a space. So far as I can tell, this has been the case even for very early implementations of make. But even modern-day ...
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9 votes
1 answer
1k views

Is it true that "do ... done" blocks in Bash do not end with "od" because od existed before Bash/Bourne shell?

The Wikipedia page about od says: Since it predates the Bourne shell, its existence causes an inconsistency in the do loop syntax. Other loops and logical blocks are opened by the name, and closed by ...
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  • 561
1 vote
1 answer
344 views

Did DEMOS have a C compiler?

DEMOS was a Soviet operating system derived from BSD Unix. The answer to this question shows that the familiar, English-derived BSD commands were essentially the same in DEMOS. Did DEMOS have a C ...
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6 votes
2 answers
324 views

DEMOS commands: Cyrillic or Roman letters? Uppercase or lowercase?

DEMOS was a Soviet operating system derived from BSD Unix. Commands in BSD are derived from English words. Did DEMOS use these same commands, develop their own commands but retain the Roman alphabet,...
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14 votes
3 answers
2k views

What were the differences between Xenix and Unix?

According to https://en.wikipedia.org/wiki/Xenix by the beginning of the nineties, SCO was selling 32-bit 386 versions of both Xenix and Unix. According to https://news.ycombinator.com/item?id=...
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40 votes
1 answer
7k views

What was "the shrinkwrap issue?"

I first read "Alice in UNIX Land" (by Lincoln Spector, Texas Computer Currents, Sept. 1989), probably around the time when it was written — and at that time didn't understand very many of ...
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1 vote
2 answers
607 views

Does an OS, in particular Unix, need special support for terminal colors? [closed]

Also of interest, would be the first OS to support color graphics in other ways (assuming it wasn't a Unix). Background: I'm thinking of playing around with Unix v6 due to all the material available, ...
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7 votes
1 answer
878 views

Unix: Why was five (SysV) released *after* seven (V7)?

AT&T released UNIX Version 7 (seven) in 1979. The same company released UNIX System V (five) in 1983. Why did the later release have a lower number?
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7 votes
3 answers
1k 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" # ...
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17 votes
1 answer
790 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 ...
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13 votes
2 answers
1k views

Why is the Unix epoch January 1st 1970?

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 ...
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30 votes
6 answers
8k 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 ...
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10 votes
2 answers
893 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 ...
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19 votes
1 answer
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 ...
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12 votes
2 answers
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 ...
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  • 273
5 votes
3 answers
868 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 ...
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43 votes
1 answer
8k 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?
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17 votes
1 answer
435 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 ...
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39 votes
6 answers
11k 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 ...
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14 votes
6 answers
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 ...
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0 votes
2 answers
270 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 ...
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31 votes
6 answers
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 ...
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6 votes
1 answer
352 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 ...
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  • 2,591
5 votes
1 answer
245 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 ...
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13 votes
0 answers
356 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.
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13 votes
2 answers
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 (...
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  • 241
61 votes
1 answer
13k 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, ...
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7 votes
2 answers
634 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 ...
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13 votes
2 answers
624 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): $ ...
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8 votes
1 answer
356 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 ...
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  • 1,760
45 votes
9 answers
8k views

What was the point of separating stdout and stderr?

I occasionally need to work with console commands and 100% of the time I want to redirect my output to a file I fail to redirect stderr as well as stdout the first time. I can't think of a single ...
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  • 587
26 votes
6 answers
6k 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 ...
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  • 465
10 votes
2 answers
850 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?
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  • 101
11 votes
6 answers
1k 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 ...
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  • 531
15 votes
1 answer
740 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 ...
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5 votes
1 answer
412 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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