What is the relationship between man pages and info pages?

Answer 1

Well, the first thing to keep in mind is that they both co-exist ... for virtually all command line utilities.

You can display a "man" page at your Linux/UNIX prompt by typing: man <command-name> (e.g., man ls) .

You can display a "info" page at your Linux/UNIX prompt by typing: info <command-name> (e.g., info ls).

You can also find both man and info pages online.

So what's the difference?

Only 2 things that are worth pointing out from where I sit.

1) Man pages are written in the quite antiquated MM (memorandum macro) language -

before modern markup/markdown standards, there was MM. There are very few people in industry still

proficient in MM ... and it kinda looks like this (the MM mnemonics start with a period and mist appear

in the 1st column of an MM src file:

.TH CORRUPT 1

.SH NAME

corrupt \- modify files by randomly changing bits

.SH SYNOPSIS

.B corrupt

[\fB\-n\fR \fIBITS\fR]

[\fB\-\-bits\fR \fIBITS\fR]

.IR file ...

.SH DESCRIPTION

.B corrupt

modifies files by toggling a randomly chosen bit.

.SH OPTIONS

.TP

.BR \-n ", " \-\-bits =\fIBITS\fR

Info pages are written in "texinfo" typesetting language.

And yes, it's newer than MM and kinda looks like this:

\input texinfo @c -*-texinfo-*-

@comment $Id@w{$}

@comment %**start of header

@setfilename sample.info

@include version.texi

@settitle GNU Sample @value{VERSION}

@syncodeindex pg cp

@comment %**end of header

@copying

This manual is for GNU Sample (version @value{VERSION}, @value{UPDATED}),

which is an example in the Texinfo documentation.

2) The info page content tends to contain more detailed information - especially for the more complex

commands like grep, find, etc. Man pages are typically briefer than info pages.

You can easily make this observation by viewing both content online, but if you count the number

of characters or lines generated by info & man at your favorite shell prompt, you might notice that the

info content is 3-4+ times the size of the man content.

For example, in my cygwin env, I found that the info content for grep was about 3X the man

content for grep.

114606 /tmp/grep_info <<< character count

34252 /tmp/grep_man

When it comes to reference documentation, I suppose having more choices is better than having

less (as long all content is consistent).

I personally tend to use man pages more than info pages because I'm typically hunting

for a minor detail at the head of the doc, so "less" usually works better for me,

and regardless, I've gotten to be proficient at searching within the man output over the years ...

If you spend a lot of time at your cygwin, macbook, Ubuntu, redhat, etc. terminal prompts, it's

handy to know that both of these formats exist for most commands.