SteveR: /* Intro to the Command Line: Part I */

2014-04-01T00:47:02Z

Intro to the Command Line: Part I

← Older revision		Revision as of 20:47, 31 March 2014
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	In command lines, most shells recognize "~" as a shortcut meaning "my		In command lines, most shells recognize "~" as a shortcut meaning "my
	home directory". So, <tt>ls ~</tt> lists the files in your home		home directory". So, <tt>ls ~ </tt> lists the files in your home
	directory.		directory.

SteveR: Created page with "= Intro to the Command Line: Part I = We tried out a few different commands this evening: * '''ls''' to list files. * '''cd''' to change directories * '''pwd''' to see what..."

2014-04-01T00:45:55Z

Created page with "= Intro to the Command Line: Part I = We tried out a few different commands this evening: * '''ls''' to list files. * '''cd''' to change directories * '''pwd''' to see what..."

New page

= Intro to the Command Line: Part I =

We tried out a few different commands this evening:

* '''ls''' to list files.
* '''cd''' to change directories
* '''pwd''' to see what directory you're currently in
* '''more''' and '''less''' to examine the contents of files
* '''id''' to see what your username is, and to find out which groups you're in

The general form for a command is

COMMAND-NAME OPTIONS ARGUMENTS

COMMAND-NAME is the name of a command, like <tt>ls</tt> or
<tt>cd</tt>.

ARGUMENTS indicate what the command should operate on. For
examine, <tt>ls /etc</tt> has an ARGUMENT of "/etc", meaning that ls
should show files in the /etc directory.

OPTIONS affect the command's behavior. For example, in <tt>ls -l
/etc</tt>, the "-l" is an option that tells ls to produce a "long"
listing.

In command lines, most shells recognize "~" as a shortcut meaning "my
home directory". So, <tt>ls ~</tt> lists the files in your home
directory.

If you want to think in terms of grammar, COMMAND is a verb, OPTIONS
are adverbs, and ARGUMENTS are direct objects.

For many commands, ARGUMENTS are optional. For example <tt>cd</tt>
(without any arguments) is equivalent to <tt>cd ~</tt>. <tt>ls</tt>
(without any arguments) is equivalent to <tt>ls .</tt> ("." means "the
current directory").

How can you tell which options a command accepts? The manual pages
are a good way to find out. For example:

man ls

Shows the manual page for the <tt>ls</tt> command.

Of course, <tt>man</tt> is just a command; it's got a manual page,
which you can see with <tt>man man</tt>.

Many commands accept <tt>--help</tt> or <tt>-h</tt> as an option, and
will respond with a brief summary of their command line syntax.

Man pages are written to be reference material; they're generally not
tutorials (though some of them are written as tutorials).

Other sources of documentation include [http://tldp.org/ TDLP], the
linux documentation project, and your distribution's web site. And of
course, searching the fine web is another way to find documentation.

Finally, we talked a little about environment variables, and the
<tt>$PAGER</tt> environment variable in particular. A "pager" is a
program for viewing files one page at a time (<tt>more</tt> and
<tt>less</tt> are two popular pagers). As an illustration, compare
this

export PAGER=more
man ls

with this

export PAGER=less
man ls

If you define a <tt>$PAGER</tt> program, man will use it to display
manual pages one screen at a time. The former shows the <tt>ls</tt>
manpage, paged through <tt>more</tt>. The latter shows the
<tt>ls</tt> manpage, paged through <tt>less</tt>. You can also do
silly things like

export PAGER=tac
man ls

to see the ls manpage displayed with the lines reversed.

[[Category:Linux Class]]

Intro to the Command Line: Part I - Revision history

SteveR: /* Intro to the Command Line: Part I */

SteveR: Created page with "= Intro to the Command Line: Part I = We tried out a few different commands this evening: * '''ls''' to list files. * '''cd''' to change directories * '''pwd''' to see what..."