When naming links to http://manpages.ubuntu.com (or other online sources for manual pages), I think <code>man *topic*</code> (e.g., `man ls`)--as suggested by [andrewsomething's answer][1] and others here--is the way to go.

However, **occasionally there are multiple manpages with the same name** (i.e., from different sections of the manual). When one actually runs the *command* <code>man *topic*</code>, typically the page for *`topic`* in the lowest-numbered section is shown, and typically this is desired. For example, running `man chmod` shows [the `chmod` page from section **1** of the manual][2].

There are [other manpages for `chmod`, though][3]. If I were to link to the manual page on the `chmod` *system call*, I would not label that link `man chmod`, because running `man chmod` doesn't show that manual page. To show that manual page on the command line, one would run `man 2 chmod` (since it's in page **2** of the manual).

Therefore, calling the link [`man 2 chmod`][4] makes the most sense.

Note that while running `man 1 chmod` shows the same page as `man chmod`--the manual page for the `chmod` *command*--I am not suggesting labeling links with the <code>man **N** *topic*</code> syntax except when it would be necessary on the command line--i.e., except when <code>man *topic*</code> would usually refer to a manpage different from the one desired.

This ambiguity can arise even when answering non-programming questions posted by novice users. The `crontab` topic is such an instance:

- [`man crontab`][5] (equivalent to `man 1 crontab`) shows the manual page for the `crontab` *command*.
- The manual page for the `crontab` *file format* (i.e., how to write a crontab), which is perhaps more commonly cited and recommended, is [`man 5 crontab`][6].

###Syntactic/Historical Note and "Citation"

Traditionally among UNIX/[*nix][7] aficionados, manual pages are referred to as <code>*topic*(**n**)</code> (e.g., [`ls(1)`][8], [`sudo(8)`][9]). This notation is useful for brevity, and when everyone knows what that means because they have to be conversant with manpages to use the system (i.e, on Unix-like OSes that are way less user-friendly or GUI-oriented than Ubuntu), and on systems where hyperlinking often cannot be facilitated (e.g., email, usenet). I am not suggesting we adopt that notation widely here, though I wouldn't necessarily edit it out of someone else's post.

However, that notation is my motivation for my suggestion to specify the section of the manual when a different section would otherwise be inferred. I would cite the <code>*topic*(**n**)</code> tradition as the source for the <code>man **n** *topic*</code> idea I've put forward in this post.


  [1]: http://meta.askubuntu.com/a/800/22949
  [2]: http://manpages.ubuntu.com/manpages/trusty/en/man1/chmod.1.html
  [3]: http://manpages.ubuntu.com/cgi-bin/search.py?q=chmod&op=&cx=003883529982892832976%3A5zl6o8w6f0s&cof=FORID%3A9&ie=UTF-8
  [4]: http://manpages.ubuntu.com/manpages/trusty/en/man2/chmod.2.html
  [5]: http://manpages.ubuntu.com/manpages/trusty/en/man1/crontab.1.html
  [6]: http://manpages.ubuntu.com/manpages/trusty/en/man5/crontab.5.html
  [7]: https://en.wikipedia.org/wiki/Unix-like
  [8]: http://manpages.ubuntu.com/manpages/trusty/en/man1/ls.1.html
  [9]: http://manpages.ubuntu.com/manpages/trusty/en/man8/sudo.8.html