[SOLVED] Probably an important detail to know in the MAN pages.
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Probably an important detail to know in the MAN pages.
Something that I have had a question about for awhile, but just now "getting around" to asking:
In the following quotation block, there is some syntax that is mysterious to me. In order to better understand how to read the man pages, would somebody answer for me the following question(s):
Non argument options that are duplicated either on the command line, in $MANOPT, or both, are not harmful. For
options that require an argument, each duplication will override the previous argument value.
General options -Cfile, --config-file=file
Use this user configuration file rather than the default of ~/.manpath.
This quotation was taken from the page for the command
My questions have to do with the placement of the equals sign following
as well as what the second usage of the word "file" means in that line. Also, I have seen other pages where the equals sign is not in bold font--what does that mean? I am getting the impression based on my readings of the man pages over the years that the line
implies more than one concept. Of course, I could be wrong. But, to the point, my questions are: (1) Can the line be read more than one way? and (2) How do I read that line? In other words, what is the sum of information that I can get from that line? And what does a non-bold equals sign mean, and what does a bold equals sign mean?
Thank you much, in advance for your help.
Last edited by theAdmiral; 05-13-2014 at 06:06 PM.
Both are the same thing. The -C is a short form for the equivalent --config-file. Thus the "file" reference is the same.
Using the long form is good for use in scripts that may embed the man command for its self documenting capability, but it is a pain to type on a command line.
This is similar to the "-d, --debug" that follows. -d is the short form, --debug the long.
Now there are some options that don't have a short form, (like --warnings), but these are very rarely used options where "-d" is used for finding out why something didn't display as expected (usually used by documentation developers).
In some cases, the short form is included to provide for backward compatibility - the option may have some extended capabilities (such as the -w, --where, --location).
In other cases the option is totally new - such as the "-e sub-extension, --extension=sub-extension" which can be useful on the command line, but because the structure is already provided, a long form also included.
Forgot one other thing.
There are sometimes multiple short form options and one long form option (here the example is the "-S list, -s list, --sections=list". This provides for compatibility with multiple systems - BSD/AIX/Solaris.
GNU developed applications tend to always have the long form available with short form. But some applications come from other places and have not been converted/translated as their source would have to be updated (and possibly the project providing them just doesn't feel like adding the code as that would also affect their runtime library too).
When using the long form, must I type the equals sign when, for example, also typing a filename? Also, what is the difference between a bold and a non-bold equals sign?
Again, thank you.
The "=" is part of the syntax.
As for the bolding/non-bolding I think that is an error in the man page as the bolding is not relevant to the command. It can even be an error in the translation to the terminal type as the original purpose of the man page was to be able to produce a fancy printed documentation (where things are italicized). The bolding is used to substitute for the lack of capability in the terminal for handling multiple fonts.
This last goes way back (historically) into the text documenting that UNIX had as a foundation. The original use for UNIX was a typesetting and text formatting system for Bell Laboratory secretaries. It was based on a macro language for generating escape sequences for typesetting. The original "man" command itself was a shell script that ran something like "pic | eqn | nroff -man" where "pic" was a preprocessing language for generating figures and diagrams (PICture), "eqn" was another for generating equations, and the "man" was a specific set of macros for man page formatting. The combination of various tools made the availability of quite elaborate documentation for both online use, and creating reference books.
Current implementations are now available where groff is the common one. groff = GNU roff, and it tends to include all of the documentation tools from UNIX, including table of contents, subscripting/superscripting, diagrams, tables, and cross reference indexes.
This was the first general text processing tool kit included as a basic part of an operating system.
Unfortunately, with the rise of the GUI a lot of the documentation tradition of UNIX has been killed - partly due to Windows not including tools, and partly due to laziness. Some of the GNU project produce documentation in "info" format that has the same goals, and that includes the ability to create man pages, but with some searchability. Again, creating the original documents has fallen by the wayside, so man pages now have a tendency to be missing, or even incomplete.