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140 votes

What was the point of separating stdout and stderr?

Because you might not want error messages in your output. According to computer scientist Stephen C. Johnson: One of the most amusing and unexpected consequences of phototypesetting was the Unix ...
117 votes
Accepted

How did people use ed?

It's a line editor (meaning, you can't see all the text at a time. You query line numbers and it spits it back, but it came before vi, where you can use hjkl to navigate up and down the screen). How ...
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113 votes
Accepted

What was the point of separating stdout and stderr?

You are thinking that all output is for human reading. For instance, take the Unix cpio command. It writes the archive to stdout, which is always redirected to a device or file. It writes the ...
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109 votes
Accepted

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

This is covered largely in the history section of Wikipedia’s entry on newlines. Basically there are two primary lineages of operating systems leading to modern-day desktop usage: Windows on the one ...
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84 votes
Accepted

What's the story behind the name "X11"?

The short version is that X11 was the first widely-disseminated version, and it turned out to be good enough to remain as-is for thirty years. X is the X Window System, which at its core is a ...
  • 98.3k
75 votes
Accepted

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

The message appears in sudo’s revision control (in its current guise) in June 1993, in the University of Colorado version of sudo, in a slightly shorter form: We trust you have received the usual ...
  • 98.3k
71 votes

How did people use ed?

The reason you can't keep a 20 line program in your head is because you don't have to any more. Same reason you probably don't know any phone numbers. But back in the day, we certainly did do this. I ...
  • 11.1k
65 votes

Why did Unix use slash as the directory separator?

Primordial Unix on the PDP-7 was in many ways very different from what we know today. Directories existed but were very awkward to use; in practice most work was done in a single directory. Most ...
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64 votes
Accepted

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

The message was This program posts news to thousands of machines throughout the entire civilized world. Your message will cost the net hundreds if not thousands of dollars to send everywhere. ...
  • 98.3k
63 votes
Accepted

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

The I/O model on "Cutler systems" – RSX-11M, VAX/VMS, Windows NT – is an asynchronous packet-driven I/O model, rather than the fundamentally synchronous I/O model of Unix. At its core, you ...
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50 votes
Accepted

What was "the shrinkwrap issue?"

The shrinkwrap issue was a vicious circle perceived by the computer industry in the late 1980s to early 1990s. In essence: With many different processors and binary formats, it was difficult for a ...
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49 votes
Accepted

Why did base64 win against uuencode?

I’m not sure about specific events, but I think the main reason Base64 “won” is that it’s one of the binary encodings supported by MIME, and MIME took over. So perhaps the question then becomes two-...
  • 98.3k
47 votes
Accepted

Why does make only accept tab-indentation?

This goes back to early versions of Make, and isn’t specific to GNU’s implementation; as explained by the author of the original Make, Stuart Feldman: Why the tab in column 1? Yacc was new, Lex was ...
  • 98.3k
43 votes
Accepted

Correct pronunciation of `vi` (Unix editor)?

vi is pronounced as the two separate letters, /ˌviːˈaɪ/ (in English); listen to the same Brian Kernighan (also re-confirming the ed pronunciation). Vim’s pronunciation is explicitly documented: Vim ...
  • 98.3k
38 votes

Why does UNIX ed not have a prompt by default

Having used ed years ago on a printing terminal (such as a teletype or a DECwriter), I think the reason for having no prompt was that on pressing RETURN after one command, you didn't have to wait for ...
37 votes
Accepted

Was Unix ever a single-user OS?

Going from “AT&T made phone switches” to the idea that Unix was intended to drive phone switches is quite a leap. The creators of Unix described its creation and development in some detail, e.g. ...
  • 98.3k
36 votes
Accepted

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

It's obviously not practical to give the whole story of many companies from start to finish in a single answer. But, generally speaking in the 1980's, the computer industry was much more fractious ...
  • 1,485
34 votes
Accepted

What are the major technical difference between Multics and Unix?

From this list of Multics features, almost all are recognizable in modern UNIX-style systems in one form or another. Looking for distinctions between is two is made difficult due to the longevity of ...
  • 3,253
34 votes

What was the purpose of those special user accounts in Unix?

Debian includes a file which describes a number of historical accounts, with details covering more than Debian; it is shipped as /usr/share/doc/base-passwd/users-and-groups.txt.gz and its source can ...
  • 98.3k
33 votes

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

Slackware still claims to support 486s: Below is a list of minimum system requirements needed to install and run Slackware. 486 processor 64MB RAM (1GB+ suggested) About 5GB+ of hard disk space for ...
  • 98.3k
33 votes
Accepted

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

You get SIGPIPE only if you try to write to a pipe that has no readers anymore. The idea is that typical unix processes run to produce output. If the output is going to a pipe, but no one is reading ...
32 votes

What was the point of separating stdout and stderr?

In UNIX, which was developed along with C, it is common to redirect the output of a command to a file or another program. For example, ls -a | more or ls -lr > index. In these cases, you would ...
  • 5,983
31 votes

How did people use ed?

Before the advent of interactive terminals (and version control programs), most programmers were used to keeping their source code on 80-column punched cards. On the first mainframe that I worked on (...
  • 2,779
30 votes

Why was UNIX never backported to the PDP-7?

The team working on Unix at the time considered the PDP-7 to be obsolete, and had no interest in making Unix into a finished system to run on it; they only used it originally because the machine was ...
  • 12.5k
30 votes

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

Memory protection. It's not that preemptive multi-tasking is expensive, or hard. It's not. It's easy. It costs (or can cost) essentially the same as cooperative multitasking. You have to save process ...
  • 11.1k
30 votes

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

In 1986 (and for a few years after that still), /dev wasn’t handled by a special file system. It was generally a directory on the root file system, and its contents were largely static: a series of ...
  • 98.3k
30 votes
Accepted

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

As far as I can tell, the phrase "other crontabs" refers not to other versions of cron, but to the per-user crontabs. The description of the differences certainly fits with the differences ...
  • 1,949
29 votes

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

I have had great success with Gentoo Linux on the earliest generation of Intel 80486 processors, though I had to patch it (below). It works on the later ones too (486DX2 and 486DX4, both clock ...
29 votes
Accepted

Why was UNIX never backported to the PDP-7?

The PDP-7 was too small and too slow; quoting Dennis M. Ritchie in The Development of the C Language: On the PDP-7 Unix system, only a few things were written in B except B itself, because the ...
  • 98.3k

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