linux-basics.html

Linus guide, Linus guide, Linus guide,

<LI><B>Filename Completion:</B><br>Tab filename completion allows you
to type in portions of a filename or program, and then press [TAB],
and it will complete the filename for you. If there's more than one
file or program that starts with what you already typed in, it will
beep, and then when you press [TAB] again it lists all the files that
start with what you initially type. Play around with it a little bit
to see what its limits are, how it can work for what you do, etc.</LI>

<LI><B><tt>ifconfig</tt>:</B><br>You can check to see what your
current IP addresses are using the <B>ifconfig</B> command.</LI>

<LI><B>HOWTO-reading HOWTO:</B><br>When looking through a Linux HOWTO,
try to read only what you think you'll need. If you're still confused,
then try additional portions of the HOWTO that you think will be
helpful. This is useful if you've figured out part of the problem and
want to know how to do the rest.</LI>

<LI><B>How big is it, anyway?:</B><br>To find out how much space a
directory and its contents take up, use the command <B>du -b
--total</B> to give you the output in bytes. There's a lot more you
can do with this command, just read the manpage using <B>man
du</B>. Another good trick is to do <B>du -b | sort +0n -r >
foo-du.txt</B>, then use <B>less</B> to look for really big
files.</LI>

<LI><B>Development packages:</B><br>In case you decided to skip
installing development packages during the installation of your
distribution, and now can't compile source into binaries that you can
use (&quot;command not found&quot; when you're following the guides on
this page), install the following packages: autoconf, automake, make,
gcc, egcs, glibc, glibc-devel, kernel-headers, libstdc++,
XFree86-devel, and binutils. This will probably vary depending on your
distribution, but they're basically what you'll need. (Based on
experiments performed on <A HREF="mailto:[e-mail]">Parker
Mead</A>)</LI>

<LI><B>Long Filenames:</B><br>Linux can handle long filenames--with
spaces, too! However, it's not a good idea to use spaces in filenames,
as it creates problems for many programs. To refer to them you'll have
to use quotation marks. So if I have a file called <TT>That report I
was working on</TT> then I'll have to edit it using <TT><B>pico
&quot;That report I was working on&quot;</B></TT>.</LI>

<LI><B>^D:</B><br>Pressing ^D (Ctrl-D) on an empty line will close
that shell, either with the <B>exit</B> or <B>logout</B> command,
whichever is appropriate. When you've already typed something, and
then you press ^D, you'll see a list of filenames that start with the
thing you typed! (<A HREF="mailto:[e-mail]">Sybren
Stuvel</A>)</LI>

<LI><B>How Do I...?:</B><br>When you know what you want to do but not
what command you need, try typing <B>apropos <I>subject</I></B>. This
will print out a list of all the man pages having to do with
<I>subject</I>.  (<A HREF="mailto:[e-mail]">Paul
Winkler</A>)</LI>

<LI><B>Instant Replay:</B><br>Another nice bash feature: typing
<B>!<I>string</I></B> will execute the most recent command that began
with <I>string</I>. (<A HREF="mailto:[e-mail]">Paul
Winkler</A>) If you type <B>!?<I>string</I></B> then it will redo the
last command with &lt;string&gt;> anywhere in the command.  I think
this is a more useful version as it makes it easier to make the last
command lookup search pattern more unique. (<A
HREF="mailto:[e-mail]">Rob Denison</A>)</LI>

<LI><B>^Z:</B><br>^Z (Control-z) stops a job. After stopping a job,
you can do two things with it - start it again in the foreground or
start it again in background. To start the job in foreground again,
use <B>fg n</B>; to start the job in background use <B>bg n</B>, where
n is the job number.  <B>jobs</B> will list all the jobs (along with
numbers) you currently have running. Note that &quot;all the jobs you
currently have running&quot; is only on the current tty - if you're
logged in as <B>joe</B> on tty1 and tty2, and you stop a job on tty2,
you can't do anything to it from tty1 (play with the <B>jobs</B>,
<B>bg</B> and <B>fg</B> commands - you'll see what I mean). Also note
that job numbers are not the same as process id (PID) numbers, so
DON'T TRY &quot;kill 2&quot; WHEN 2 IS THE JOB NUMBER FOR
ANYTHING. (Instead, try <B>kill %2</B>. Thanks to <A
HREF="mailto:[e-mail]">Mark Schreiber</A> for this one.)
If you have many jobs running background and make the simple mistake
of killing a job number instead of a PID, you risk having some large
nasty problems. Trust me on that one. Why? Because a lot of very
important processes are loaded with very low PIDs, and it's a bad idea
to be signalling them without a good reason. (<A
HREF="mailto:[e-mail]">jbm</a>) </LI>

<LI><B>No more root Logins:</B><br>To never have to log on as root
again (having to log on as root is generally looked down upon as a bad
practice), try two very useful utilities: <B>su</B> and <B>sudo</B>.
&quot;su&quot; allows users to become the superuser if they know the
superuser password. Simply type <B>su -</B> at the prompt (the
&quot;-&quot; is so that it will discard the PATH variable by the user
you're using to become the superuser; this means it is almost exactly
like having a root login), and the program will ask for the
password. Enter it in, and poof - your $ is now a #. Type <B>exit</B>
to get back to being a normal user. (Note: you can also use <B>su -
username</B>; &quot;su&quot; will prompt you for
&quot;username&quot;'s password. If you are a superuser, you can just
do <B>su - username</B> and it won't prompt for a password. Use
&quot;exit&quot; to get back to being your usual self). This is very
useful for installing system-wide programs, or moving things
around. (<A HREF="mailto:[e-mail]">jbm</a>)</LI>

<li><b>Less is More:</B><br>Most of the new Linux distributions come
with a version of <b>less</b> that will automagically handle gzip'd
and zip'd files. This means you can just do <b><tt>less
my-big-gzipped-text-file.gz</tt></b> and it will act just like normal
<b>less</b>! (Otherwise, try <B>zless</B>.) Also, <b>less</b> can read
the directory structure of tar files - gzip'd ones, too. So to make
sure that new package you got actually creates its own directory, do
<b><tt>less foobar-1.0.tar.gz</tt></b> to see where all it puts
things; it'll spit out a listing somewhat like <b><tt>ls
-l</tt></b>. (<a href="mailto:[e-mail]">jbm</a>)</LI>

<li><B>Screenshots:</B><br>To grab a screenshot in X, use
<b>xv</b>. Open up <b>xv</b> and click "grab". Set the delay to 5
seconds and check "Hide XV windows". Click Grab and then click on the
root window (your desktop) and leave the mouse cursor over the desktop
(not over a window). The edge of your screen will blink and your
computer will beep to tell you it's grabbed the screenshot. Move the
<b>xv</B> window a little bit, and suddenly your whole screen will be
filled with the screenshot image. Right-click on that to bring up the
control window, and save the image.  (<a
href="mailto:[e-mail]">jbm</a>) You can also use the
<b>import</b> command from the ImageMagick package. Just type this in
an xterm: <b>import foobar.jpeg</b> and then click on the window you
want to grab. You can do other formats than jpeg, too. To grab the
whole screen, just do <b>import -window root wholescreen.jpg</b>. You
can do a lot of other tricks, like leaving out window borders,
delaying a number of seconds, grabbing a sequence of images to make an
animated GIF, etc. See <b>man import</b>. (Paul Winkler, <A
HREF="mailto:[e-mail]">[e-mail]</A>.</P>

</LI>

</UL>

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<P>Got any tips of your own to add? <A
HREF="mailto:[e-mail]">Let me know</A> and your name and
a link to your e-mail address or website will be included.</P>

<HR>

<P><B><FONT SIZE="-1">Copyright &copy; 1997-1999 <A
HREF="mailto:[e-mail]">Joshua Go ([e-mail])</A>. All
rights reserved. Permission to use, distribute, and copy this document is
hereby granted. You may modify this document as long as credit to me is
given.</FONT></B></P>

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