Many programs can offer immediate help without the need for searching
out man pages, info pages, or other documentation. It is a very
widely-respected convention that programs offer help when invoked with an
appropriate switch. Programs that support only what are called ``short
options,'' options formed by a minus sign and a single letter, often print
help when the
-h switch is used. Programs that
support ``long options,'' options formed with two minus signs and a word,
often accept a
--help switch. The long help
option is particularly well-supported by GNU programs.
Example 11-3. Getting help from the gzip program
$ gzip --help gzip 1.3.2 (2001-11-03) usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...] -c --stdout write on standard output, keep original files unchanged -d --decompress decompress -f --force force overwrite of output file and compress links -h --help give this help -l --list list compressed file contents -L --license display software license -n --no-name do not save or restore the original name and time stamp -N --name save or restore the original name and time stamp -q --quiet suppress all warnings -r --recursive operate recursively on directories -S .suf --suffix .suf use suffix .suf on compressed files -t --test test compressed file integrity -v --verbose verbose mode -V --version display version number -1 --fast compress faster -9 --best compress better file... files to (de)compress. If none given, use standard input. Report bugs to <firstname.lastname@example.org>.
Some programs also support a
which in most shells must be typed as -\?.
Other programs will also print help whenever they are passed incorrect
On many systems, miscellaneous documentation will be found under the /usr/doc or /usr/share/doc directory. For example, the mutt program, a popular email client has an extensive user manual that is neither man pages nor Texinfo documentation. On many systems, it can be found in /usr/share/doc/mutt/manual.txt.gz. In this case, the documentation is a compressed text file (as indicated by its extension). It can be viewed easily with zless, a version of less that automatically uncompresses compressed files.
Example 11-4. Viewing the mutt user manual.
The Mutt E-Mail Client by Michael Elkins <email@example.com> version 1.3.28 ``All mail clients suck. This one just sucks less.'' -me, circa 1995 ______________________________________________________________________ Table of Contents 1. Introduction 1.1 Mutt Home Page 1.2 Mailing Lists 1.3 Software Distribution Sites 1.4 IRC 1.5 USENET 1.6 Copyright 2. Getting Started 2.1 Moving Around in Menus 2.2 Editing Input Fields 2.3 Reading Mail - The Index and Pager 2.3.1 The Message Index 188.8.131.52 Status Flags 2.3.2 The Pager 2.3.3 Threaded Mode 2.3.4 Miscellaneous Functions 2.4 Sending Mail 2.4.1 Editing the message header 2.4.2 Using Mutt with PGP 2.4.3 Sending anonymous messages via mixmaster. 2.5 Forwarding and Bouncing Mail 2.6 Postponing Mail lines 1-32
The Linux community developed in parallel with the Internet community. As a consequence, Linux information is often easily found on the Internet. Many times, help is as close as a search at google.com for your question and the word ``linux.'' Google also has a ``Linux topic search,'' available at www.google.com/linux.