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I have seen on many occasions a name of a function (frankly speaking I just call it function because of it typical appearance, they are though sometimes named commands or system calls but I do not know the idea behind labelling them differently), which contains a number within the brackets part of it, like in exec(1) exec(2) exec(3).

What is the meaning behind putting numbers into them ?

marked as duplicate by jasonwryan, Stéphane Chazelas, slm Mar 24 '15 at 21:55

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    yes, but I think this is one of the questions that should be redundant as long as they have different key terms in the question, because even if someone has seen some(number) it is not necessary he would associate it with the term "man" or "manual" , but for instance function , system call or something else. – Abdul Al Hazred Mar 24 '15 at 21:04
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    I agree with Al Hazred here. The question is, in fact, different, due only to the variant interpretations of exec(2). – Bruce Ediger Mar 24 '15 at 21:15
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exec here could be a system call or a bash built-in or something else from this . And respective man pages related to system call or bash built-in refer to the exec's man page with numbers in the brackets. So if I want to refer to manpage of bash built-in, I would say exec(1) and if I want to refer to manpage of system call exec() i would say exec(2)

The number referrs to particular manpage. When you see exec(2) in a manpage. To know about that particular referred exec you should say man 2 exec

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These numbers disambiguate manual pages that have the same name. They represent the manual section that the page should be retrieved from. As an excerpt from Wikipedia states:

The manual is generally split into eight numbered sections, organized as follows [...]

  • I am still somehow confused, does this mean that exec(1), exec(2),...exec(8) is about the same "function" , but eight different aspects of it ? – Abdul Al Hazred Mar 24 '15 at 20:19
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    Lets say you want to know about exec(3), you do man 1 exec and found out that its a bash built-in command and not a system call exec(). Then you do man 3 exec which is about a system call. So exec here is not necessarily a system call every time. it could be something else (bash built in) with the same name. – Milind Dumbare Mar 24 '15 at 20:23
  • so, the same name is not intended, and some(1) is not related to some(2) or some(8) in their functionality , except the core-meaning of its name. So one some(x) can do something to A and some(y) can do something to B, like theoretically scribble(1) writes something onto the display, scribble(2) writes something onto a critical location like RAM adress, scribble(3) enables some programming language to write something and scribble(7) is a game that teaches how to spell english words ? – Abdul Al Hazred Mar 24 '15 at 20:45
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The numbers are the sections in the manual. (1), for example, are commands.

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