On my system (Darwin 15.5.0), man(1) opens as follows:

       man - format and display the on-line manual pages

The file the page is formatted from, however, is clearly on disk:

% man -w man
% file `man -w man`
/usr/share/man/man1/man.1: troff or preprocessor input text

So, "on-line" in this case does not mean "online," as in, "somewhere else accessible over the Internet."

Does "on-line" just mean that my system is powered on? If so, why bother specifying that in the first place, i.e., isn't it obvious that I'm reading a page that the formatter processed? Or, when the description was written, was it a huge deal to have a manual on disk because most "manuals" then were paper volumes? Is this usage of "on-line," hyphen and all, still common in computing?

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    On-line does not mean what you think it means. The network can be on or off line, but now people have started to use it to mean the network. Probably because they did not know what the word means. Another similar word is wireless, meaning without wires. I had an interesting conversation a few year back, trying to buy a wireless internet connection, but the company wanted to arrange a time to come and fit the wire to my house. They did not know what wireless means. Or mini computer, a computer the size of a small car, as opposed to a room. Not a computer smaller than a micro-computer. – ctrl-alt-delor Jul 10 '16 at 21:48
  • You're also reading meaning into the hyphen where there is none. – Lightness Races in Orbit Jul 11 '16 at 13:26

In contrast to a printed (hard-copy) manual, which you could read off-line (while not using a computer).

The term dates back (at least) to time-sharing systems. Users may have had a terminal which could be used for typing text, punching paper tapes. But they were only able to use the computer when they were on-line (the "line" referring to the communications link from the terminal to the computer).

Lots of English is that way: you likely use terms which on reflection you might not consider up-to-date.

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    Note that the number in man(1) originally literally meant that the command in question was in volume 1 of the printed manual. – chrylis -on strike- Jul 11 '16 at 4:08
  • When Unix was first released and "reading on-line" meant "waiting for your typewriter-terminal to print something on a roll of paper at about 5 characters per second" the tradeoff between printed books and on-line documentation was rather different from what it is today. – alephzero Jul 11 '16 at 12:35
  • Actually, TeleType did 10cps. 30cps was more typical of the terminals used in the early 1970s. Bell Labs developers didn't use low-cost terminals (those were limited to uppercase). – Thomas Dickey Jul 11 '16 at 20:25

The word "on-line" is used in the sense "operating under the direct control of, or connected to, a main computer." Reading a manual "on-line" is therefore the same as reading it "on the computer".

This is in contrast to "off-line" in the sense "operating independently of, or disconnected from, an associated computer." Reading a manual "off-line" is therefore the same as reading it by some other means, probably on paper (or asking the in-house wizard who knows every manual by heart).

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    Alternatively: "On-line, adj.: The idea that a human being should always be accessible to a computer." – Satō Katsura Jul 11 '16 at 5:36

Indeed in this context "online" means "on a computer" as opposed to printed on paper.

Source: I was responsible for getting new versions of those manuals printed and reproduced at the MIT Lab for Computer Science back in the 70s.

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