ggonza at tin.itLet's start politically correct. Throughout this document I say ``Linux'', but I mean ``GNU/Linux''. Please go to http://www.gnu.org/gnu/linux-and-gnu.html to see why.
You want to switch from the DOS/Windows world to Linux? Good idea: Linux is technically superior to DOS, Windows 9x and even Windows NT. But beware: it might not be useful for you. These are the main differences between DOS/Windows and Linux:
It's up to you to decide what you need. Furthermore, Linux gives you power, but it takes some time to learn how to harness it. Thus, if mostly need commercial sw, or if you don't feel like learning new commands and concepts, you had better look elsewhere. Be aware that many newcomers give up because of initial difficulties.
Work is underway to make Linux simpler to use, but don't expect to be proficient with it unless you read a lot of documentation and use it at least for a few months. Linux won't give you instant results. In spite of these warnings, I'm 100% confident that if you are the right user type you'll find in Linux your computer Nirvana. By the way, Linux + DOS/Win can coexist happily on the same machine.
Prerequisites for this howto: I'll assume that
COMMAND.COM) is bash.
Unless specified, all information in this work is aimed at bad ol' DOS. There is information about Windows here and there, but bear in mind that Windows and Linux are totally different, unlike DOS that is sort of a UNIX poor relation.
Please also note that this work is neither a complete primer nor a configuration guide!
The latest version of this document is available in several formats on http://www.linuxdoc.org.
You installed Linux and the programs you needed on the PC. You gave yourself
an account (if not, type adduser yourname now!) and Linux
is running. You've just entered your name and password, and now you are
looking at the screen thinking: ``Well, now what?''
Now, don't despair. You're almost ready to do the same things you used to do with DOS/Win, and many more. If you were running DOS/Win instead of Linux, you would be doing some of the following tasks:
You'll be glad to know that these tasks can be accomplished under Linux in a fashion similar to DOS. Under DOS, the average user uses very few of the 100+ commands available: the same, up to a point, applies to Linux.
The best way to learn something new is to get your feet wet. You are strongly encouraged to experiment and play with Linux: unless you login as ``root'', you can't damage the system that way. A few points:
There are many ways to get help with Linux. The most important are:
help or, better, man bash or info bash;
man command that invokes
the manual (``man'') page of command. Alternatively, type info
command that invokes, if available, the info page pertinent of
command; info is a hypertext-based documentation system, perhaps
not intuitive to use at first. Finally, you may try apropos command
or whatis command. With all of these commands, press `q' to exit.
Throughout this work, examples will often follow the following format:
<...> is a required argument, while [...] an optional one.
Example:
$ tar -tf <file.tar> [> redir_file]
file.tar must be indicated, but redirection to redir_file
is optional.
``RMP'' means ``please Read the Man Pages for further information''. I can't stress enough how important reading the documentation is.
When the prompt of a command example is #, the command can only
be performed by root.
Want to strike out? Have a look at this table:
DOS Linux Notes
------------------------------------------------------------------------------
ATTRIB (+-)attr file chmod <mode> file completely different
BACKUP tar -Mcvf device dir/ ditto
CD dirname\ cd dirname/ almost the same syntax
COPY file1 file2 cp file1 file2 ditto
DEL file rm file beware - no undelete
DELTREE dirname rm -R dirname/ ditto
DIR ls not exactly the same syntax
DIR file /S find . -name file completely different
EDIT file vi file I think you won't like it
jstar file feels like dos' edit
EDLIN file ed file forget it
FORMAT fdformat,
mount, umount quite different syntax
HELP command man command, same philosophy
info command
MD dirname mkdir dirname/ almost the same syntax
MORE < file less file much better
MOVE file1 file2 mv file1 file2 ditto
NUL /dev/null ditto
PRINT file lpr file ditto
PRN /dev/lp0,
/dev/lp1 ditto
RD dirname rmdir dirname/ almost the same syntax
REN file1 file2 mv file1 file2 not for multiple files
RESTORE tar -Mxpvf device different syntax
TYPE file less file much better
WIN startx poles apart!
If you need more than a table of commands, please refer to the following sections.
Good news: with Linux you type much less at the prompt, because the
bash shell types for you whenever possible, and features cool line
editing capabilities. To begin with, the arrow-up key recalls previous
command lines; but there's more. Pressing <TAB> completes file and
directory names, so typing
$ ls /uTABloTABbTAB
is like typing
$ ls /usr/local/bin
If there were ambiguities, as typing
$ ls /uTABloTABiTAB
bash stops because it doesn't know if you mean
/usr/local/info or /usr/local/include. Supply more
characters then press <TAB> again.
Other useful key presses are <ESC-BACKSPACE> that deletes a word to the left, while <ESC-D> deletes a word to the right; <ESC-F> moves the cursor one word to the right, <ESC-B> to the left; <CTRL-A> moves to the beginning of the line, <CTRL-E> to the end. The <ALT> key is equivalent to <ESC>.
Enough for now. Once you get used to these shortcuts, you'll find the DOS prompt very annoying...
Linux has a structure of directories and files very similar to that of DOS/Win. Files have filenames that obey special rules, are stored in directories, some are executable, and among these most have command switches. Moreover, you can use wildcard characters, redirection, and piping. There are only a few minor differences:
NOTENOUG.TXT. Under Linux we can do better. If you installed Linux
using a file system like ext2 or umsdos, you can use longer filenames (up to
255 characters), and with more than one dot: for example,
This_is.a.VERY_long.filename. Please note that I used both upper
and lower case characters: in fact...
FILENAME.tar.gz and filename.tar.gz
are two different files. ls is a command, LS is a mistake;
$ # the following command makes a directory called "My old files"
$ mkdir "My old files"
$ ls
My old files bin tmp
!*$&#.
*' at the end of their name when you issue the ls -F
command. For example:
$ ls -F
I_am_a_dir/ cindy.jpg cjpg* letter_to_Joe my_1st_script* old~
cjpg* and my_1st_script* are executables, that
is ``programs''. Under DOS, backup files end in .BAK, while under Linux they
end with a tilde `~'. Further, a file whose name starts with
a dot is considered as hidden. Example: the file
.I.am.a.hidden.file won't show up after the ls command;
/switch, Linux
switches with -switch or --switch. Example: dir
/s<tt> becomes ls -R. Note that many DOS programs, like
PKZIP or ARJ, use UNIX-style switches.
You can now jump to Section Translating Commands from DOS to Linux, but if I were you I'd read on.
UNIX has a type of file that doesn't exist under DOS: the symbolic link.
This can be thought of as a pointer to a file or to a directory, and can be
used instead of the file or directory it points to; it's similar to Windows
shortcuts. Examples of symbolic links are /usr/X11, which points to
/usr/X11R6; /dev/modem, which points to either
/dev/ttyS0 or /dev/ttyS1.
To make a symbolic link:
$ ln -s <file_or_dir> <linkname>
Example:
$ ln -s /usr/doc/g77/DOC g77manual.txt
Now you can refer to g77manual.txt instead of
/usr/doc/g77/DOC. Links appear like this in directory listings:
$ ls -F
g77manual.txt@
$ ls -l
(several things...) g77manual.txt -> /usr/doc/g77/DOC
DOS files and directories have the following attributes: A (archive), H (hidden), R (read-only), and S (system). Only H and R make sense under Linux: hidden files start with a dot, and for the R attribute, read on.
Under UNIX a file has ``permissions'' and an owner, who in turn belongs to a ``group''. Look at this example:
$ ls -l /bin/ls
-rwxr-xr-x 1 root bin 27281 Aug 15 1995 /bin/ls*
The first field contains the permissions of the file /bin/ls, which
belongs to root, group bin. Leaving the remaining information aside,
remember that -rwxr-xr-x means, from left to right:
- is the file type (- = ordinary file, d =
directory, l = link, etc); rwx are the permissions for the
file owner (read, write, execute); r-x are the permissions for the
group of the file owner (read, execute); (I won't cover the concept of
group, you can survive without it as long as you're a beginner ;-)
r-x are the permissions for all other users (read, execute).
The directory /bin has permissions, too: see Section
Directories Permissions for further
details. This is why you can't delete the file /bin/ls unless you
are root: you don't have the permission to do so. To change a file's
permissions, the command is:
$ chmod <whoXperm> <file>
where who is u (user, that is owner), g (group),
o (other), X is either + or -, perm is r
(read), w (write), or x (execute). Common examples of
chmod use are the following:
$ chmod +x file
this sets the execute permission for the file.
$ chmod go-rw file
this removes read and write permission for everyone but the owner.
$ chmod ugo+rwx file
this gives everyone read, write, and execute permission.
# chmod +s file
this makes a so-called ``setuid'' or ``suid'' file---a file that everyone can execute with its owner's privileges. Typically, you'll come across root suid files; these are often important system files, like the X server.
A shorter way to refer to permissions is with digits: rwxr-xr-x can
be expressed as 755 (every letter corresponds to a bit: --- is 0,
--x is 1, -w- is 2, -wx is 3...). It looks
difficult, but with a bit of practice you'll understand the concept. root,
being the superuser, can change everyone's file permissions. RMP.
On the left, the DOS commands; on the right, their Linux counterpart.
ATTRIB: chmod
COPY: cp
DEL: rm
MOVE: mv
REN: mv
TYPE: more, less, cat
Redirection and plumbing operators: < > >> |
Wildcards: * ?
nul: /dev/null
prn, lpt1: /dev/lp0 or /dev/lp1; lpr
DOS Linux
---------------------------------------------------------------------
C:\GUIDO>ATTRIB +R FILE.TXT $ chmod 400 file.txt
C:\GUIDO>COPY JOE.TXT JOE.DOC $ cp joe.txt joe.doc
C:\GUIDO>COPY *.* TOTAL $ cat * > total
C:\GUIDO>COPY FRACTALS.DOC PRN $ lpr fractals.doc
C:\GUIDO>DEL TEMP $ rm temp
C:\GUIDO>DEL *.BAK $ rm *~
C:\GUIDO>MOVE PAPER.TXT TMP\ $ mv paper.txt tmp/
C:\GUIDO>REN PAPER.TXT PAPER.ASC $ mv paper.txt paper.asc
C:\GUIDO>PRINT LETTER.TXT $ lpr letter.txt
C:\GUIDO>TYPE LETTER.TXT $ more letter.txt
C:\GUIDO>TYPE LETTER.TXT $ less letter.txt
C:\GUIDO>TYPE LETTER.TXT > NUL $ cat letter.txt > /dev/null
n/a $ more *.txt *.asc
n/a $ cat section*.txt | less
Notes:
* is smarter under Linux: * matches all files
except the hidden ones; .* matches all hidden files (but also the
current directory `.' and parent directory `..': beware!);
*.* matches only those that have a `.' in the middle or
that end with a dot; p*r matches both `peter' and `piper';
*c* matches both `picked' and `peck';
more, press <SPACE> to read through the
file, `q' to exit. less is more intuitive and lets you use the
arrow keys;
UNDELETE, so think twice before
deleting anything;
< > >>, Linux has
2> to redirect error messages (stderr); moreover,
2>&1 redirects stderr to stdout, while 1>&2
redirects stdout to stderr;
[]. Usage: [abc]*
matches files starting with a, b, c; *[I-N1-3] matches files ending
with I, J, K, L, M, N, 1, 2, 3;
lpr <file> prints a file in background. To check the
status of the print queue, use lpq; to remove a file from the print
queue, use lprm;
RENAME; that is, mv *.xxx
*.yyy won't work. A REN-like command is available on
ftp://metalab.unc.edu/pub/Linux/utils/file;
cp -i and mv -i to be warned when a file is
going to be overwritten.
To run a program, type its name as you would do under DOS. If the directory
(Section
Using Directories) where the program
is stored is included in the PATH (Section
System Initialisation Files), the program will start. Exception:
unlike DOS, under Linux a program located in the current directory won't run
unless the directory is included in the PATH. Escamotage: being
prog your program, type ./prog.
This is what the typical command line looks like:
$ command [-s1 [-s2] ... [-sn]] [par1 [par2] ... [parn]] [< input] [> output]
where -s1, ..., -sn are the program switches,
par1, ..., parn are the program parameters. You can issue
several commands on the command line:
$ command1 ; command2 ; ... ; commandn
That's all about running programs, but it's easy to go a step beyond. One of the main reasons for using Linux is that it is a multitasking os---it can run several programs (from now on, processes) at the same time. You can launch processes in background and continue working straight away. Moreover, Linux lets you have several sessions: it's like having many computers to work on at once!
su - <loginname>. Example: su - root. This
is useful, for instance, when you need to perform a task that only root can
do.
exit. If there are stopped jobs (see
later), you'll be warned.
&'
at the end of the command line:
$ progname [-switches] [parameters] [< input] [> output] &
[1] 123
[1]; see
below), and with a PID (Process Identification Number; 123 in our example).
ps ax. This will
output a list of currently running processes.
kill <PID>. You
may need to kill a process when you don't know how to quit it the right
way.... Unless you're root, you can't kill other people's processes.
Sometimes, a process will only be killed by kill -SIGKILL
<PID>.
In addition, the shell allows you to stop or temporarily suspend a process,
send a process to background, and bring a process from background to
foreground. In this context, processes are called ``jobs''.
jobs. Here the jobs are
identified by their job number, not by their PID.
bg
<%job> (it becomes a job).
fg <%job>. To bring
to foreground the last job sent to background, simply type fg.
kill <%job> where <job> may
be 1, 2, 3,...
Using these commands you can format a disk, zip a bunch of files, compile a program, and unzip an archive all at the same time, and still have the prompt at your disposal. Try this with Windows, just to see the difference in performance (if it doesn't crash, of course).
To run a program on a remote machine whose name is
remote.machine.edu:
$ telnet remote.machine.edu
After logging in, start your favourite program. Needless to say, you must have a shell account on the remote machine.
If you have X11, you can even run an X application on a remote computer,
displaying it on your X screen. Let remote.machine.edu be the
remote X computer and let local.linux.box be your Linux machine. To
run from local.linux.box an X program that resides on
remote.machine.edu, do the following:
xterm or equivalent terminal emulator,
then type:
$ xhost +remote.machine.edu
$ telnet remote.machine.edu
remote:$ DISPLAY=local.linux.box:0.0
remote:$ progname &
DISPLAY..., you may have to write: setenv DISPLAY
local.linux.box:0.0. It depends on the remote shell.)
Et voila! Now progname will start on remote.machine.edu
and will be displayed on your machine. Don't try this over the modem though,
for it's too slow to be usable. Moreover, this is a crude and insecure
method: please read the ``Remote X Apps mini-HOWTO'' at
http://www.linuxdoc.org/HOWTO/mini/Remote-X-Apps.html.
We have seen the differences between files under DOS/Win and Linux. As for
directories, under DOS/Win the root directory is \, under Linux
it is /. Similarly, nested directories are separated by \
under DOS/Win, by / under Linux. Example of file paths:
DOS: C:\PAPERS\GEOLOGY\MID_EOC.TEX
Linux: /home/guido/papers/geology/middle_eocene.tex
As usual, .. is the parent directory and . is the current
directory. Remember that the system won't let you cd, rd,
or md everywhere you want. Each user has his or her stuff in a
directory called `home', given by the system administrator; for instance, on
my PC my home dir is /home/guido.
Directories, too, have permissions. What we have seen in Section
Permissions and Ownership applies to directories as
well (user, group, and other). For a directory, rx means you can
cd to that directory, and w means that you can delete a
file in the directory (according to the file's permissions, of course), or
the directory itself.
For example, to prevent other users from snooping in
/home/guido/text:
$ chmod o-rwx /home/guido/text
DIR: ls, find, du
CD: cd, pwd
MD: mkdir
RD: rmdir
DELTREE: rm -rf
MOVE: mv
DOS Linux
---------------------------------------------------------------------
C:\GUIDO>DIR $ ls
C:\GUIDO>DIR FILE.TXT $ ls file.txt
C:\GUIDO>DIR *.H *.C $ ls *.h *.c
C:\GUIDO>DIR/P $ ls | more
C:\GUIDO>DIR/A $ ls -l
C:\GUIDO>DIR *.TMP /S $ find / -name "*.tmp"
C:\GUIDO>CD $ pwd
n/a - see note $ cd
ditto $ cd ~
ditto $ cd ~/temp
C:\GUIDO>CD \OTHER $ cd /other
C:\GUIDO>CD ..\TEMP\TRASH $ cd ../temp/trash
C:\GUIDO>MD NEWPROGS $ mkdir newprogs
C:\GUIDO>MOVE PROG .. $ mv prog ..
C:\GUIDO>MD \PROGS\TURBO $ mkdir /progs/turbo
C:\GUIDO>DELTREE TEMP\TRASH $ rm -rf temp/trash
C:\GUIDO>RD NEWPROGS $ rmdir newprogs
C:\GUIDO>RD \PROGS\TURBO $ rmdir /progs/turbo
Notes:
rmdir, the directory to remove must be empty. To
delete a directory and all of its contents, use rm -rf (at your own
risk).
~' is a shortcut for the name of your
home directory. The commands cd or cd ~ will take you to
your home directory from wherever you are; the command cd ~/tmp
will take you to /home/your_home/tmp.
cd - ``undoes'' the last cd.
There are two ways to manage devices under Linux: the DOS way and the UNIX way. Take your pick.
Most Linux distributions include the Mtools suite, a set of commands that
are perfectly equivalent to their DOS counterpart, but start with an `m':
i.e., mformat, mdir, mdel, mmd, and so
on. They can even preserve long file names, but not file permissions. If you
configure Mtools editing a file called /etc/mtools.conf (a
sample is provided in the distribution), you can also access the DOS/Win
partition, the CD--ROM, and the Zip drive. To format a fresh disk though,
the mformat command won't do. As root, you'll have to issue this
command beforehand: fdformat /dev/fd0H1440.
You can't access files on the floppy with a command like, say, less
a:file.txt! This is the disadvantage of the DOS way of accessing disks.
UNIX has a different way to handle devices. There are no separate volumes like A: or C:; a disk, be it a floppy or whatever, becomes part of the local file system through an operation called ``mounting''. When you're done using the disk, before extracting it you must ``unmount'' it.
Physically formatting a disk is one thing, making a file system on it is
another. The DOS command FORMAT A: does both things, but under
Linux there are separate commands. To format a floppy, see above; to create
a file system:
# mkfs -t ext2 -c /dev/fd0H1440
You can use dos, vfat (recommended) or other formats
instead of ext2. Once the disk is prepared, mount it with the
command
# mount -t ext2 /dev/fd0 /mnt
specifying the right file system if you don't use ext2. Now you can
address the files in the floppy using /mnt instead of A: or B:.
Examples:
DOS Linux
---------------------------------------------------------------------
C:\GUIDO>DIR A: $ ls /mnt
C:\GUIDO>COPY A:*.* $ cp /mnt/* .
C:\GUIDO>COPY *.ZIP A: $ cp *.zip /mnt
C:\GUIDO>EDIT A:FILE.TXT $ jstar /mnt/file.txt
C:\GUIDO>A: $ cd /mnt
A:> _ /mnt/$ _
When you've finished, before extracting the disk you must unmount it with the command
# umount /mnt
Obviously, you have to fdformat and mkfs only unformatted
disks, not previously used ones. If you want to use the drive B:, refer to
fd1H1440 and fd1 instead of fd0H1440 and
fd0 in the examples above.
Needless to say, what applies to floppies also applies to other devices; for instance, you may want to mount another hard disk or a CD--ROM drive. Here's how to mount the CD--ROM:
# mount -t iso9660 /dev/cdrom /mnt
This was the ``official'' way to mount your disks, but there's a trick in store. Since it's a bit of a nuisance having to be root to mount a floppy or a CD--ROM, every user can be allowed to mount them this way:
# mkdir /mnt/floppy ; mkdir /mnt/cdrom
# chmod 777 /mnt/floppy /mnt/cd*
# # make sure that the CD-ROM device is right
# chmod 666 /dev/hdb ; chmod 666 /dev/fd*
/dev/cdrom /mnt/cdrom iso9660 ro,user,noauto 0 0
/dev/fd0 /mnt/floppy vfat user,noauto 0 0
Now, to mount a DOS floppy and a CD--ROM:
$ mount /mnt/floppy
$ mount /mnt/cdrom
/mnt/floppy and /mnt/cdrom can now be accessed by every user. Remember that allowing everyone to mount disks this way is a gaping security hole, if you care.
Two useful commands are df, which gives information on the mounted
file systems, and du dirname which reports the disk space consumed
by the directory.
There are several packages to help you, but the very least you can do for a multi-volume backup is (as root):
# tar -M -cvf /dev/fd0H1440 dir_to_backup/
Make sure to have a formatted floppy in the drive, and several more ready. To restore your stuff, insert the first floppy in the drive and do:
# tar -M -xpvf /dev/fd0H1440
The ``equivalent'' of Windows is the graphic system X Window System. Unlike Windows or the Mac, X11 wasn't designed for ease of use or to look good, but just to provide graphic facilities to UNIX workstations. These are the main differences:
fvwm, basic but nice and memory efficient, fvwm2-95,
Afterstep, WindowMaker, Enlightenment, and many
more. The w.m. is usually invoked from .xinitrc;
.fvwmrc, .fvwm2rc95, .steprc, etc. A sample
configuration file is typically found in
/etc/X11/window-manager-name/system.window-manager-name;
xdvi,
xman, xcalc); others use Motif (netscape), others
still use Tcl/Tk, Qt, Gtk, XForms, and what have you. Nearly all of these
libraries provide roughly the same look and feel as Windows;
xsetroot or xloadimage;
xclipboard, that provides for multiple clipboard buffers;
This said, good news for you. There are projects that aim at making X11 look and behave as coherently as Windows. Gnome, http://www.gnome.org, and KDE, http://www.kde.org, are simply awesome. Most likely your distribution uses either or both. You won't regret your Windows desktop anymore!
Two important files under DOS are AUTOEXEC.BAT and
CONFIG.SYS, which are used at boot time to initialise the system,
set some environment variables like PATH and FILES, and possibly launch a
program or batch file. Additionally, Windows has the infamous registry---one
of the worst ideas ever conceived in computer science.
Under Linux there are lots of initialisation files, some of which you had better not tamper with until you know exactly what you are doing; they reside in the /etc tree. All configuration can be done editing plain text files. If all you need is setting the PATH and other environment variables, or you want to change the login messages or automatically launch a program on login, have a look at the following files:
FILES NOTES
/etc/issue sets pre-login message
/etc/motd sets post-login message
/etc/profile sets $PATH and other variables, etc.
/etc/bashrc sets aliases and functions, etc.
/home/your_home/.bashrc sets your aliases + functions
/home/your_home/.bash_profile or
/home/your_home/.profile sets environment + starts your progs
If the latter file exists (note that it is a hidden file), it will be read after the login, and the commands therein will be executed.
Example---look at this .bash_profile:
# I am a comment
echo Environment:
printenv | less # equivalent of command SET under DOS
alias d='ls -l' # easy to understand what an alias is
alias up='cd ..'
echo "I remind you that the path is "$PATH
echo "Today is `date`" # use the output of the command 'date'
echo "Have a good day, "$LOGNAME
# The following is a "shell function"
ctgz() # List the contents of a .tar.gz archive.
{
for file in $*
do
gzip -dc ${file} | tar tf -
done
}
# end of .profile
$PATH and $LOGNAME, you guessed right, are
environment variables. There are many others to play with; for instance, RMP
for apps like less or bash.
Putting this line in your /etc/profile will provide the rough
equivalent of PROMPT $P$G:
export PS1="\w\\$ "
Under Linux, virtually everything can be tailored to your needs. Most
programs have one or more initialisation files you can fiddle with, often as
a .prognamerc in your home dir. The first ones you'll want to
modify are:
.inputrc: used by bash to define key bindings;
.xinitrc: used by startx to initialise X Window
System;
.fvwmrc: used by the window manager fvwm.
.joerc, .jstarrc: used by the editor joe;
.jedrc: used by the editor jed;
.pinerc: used by the mail reader pine;
.Xdefault: used by many X programs.
For all of these and the others you'll come across sooner or later, RMP. Perhaps I could interest you in the Configuration HOWTO, http://www.linuxdoc.org/HOWTO/Config-HOWTO.html?
Not only is ``Dialup Networking'' available under Linux, it's also more stable and quicker. The name of the game is ``PPP'', the protocol employed for connecting to the Internet using modems. All you need is a tool that dials out and makes the connection.
To retrieve your mail from the ISP's server you need a tool called ``email
fetcher'' that uses the POP protocol; when the mail is fetched it will
appear as though it had been directly delivered to your Linux box. You'll
then use a MUA (Mail User Agent) like pine, mutt,
elm or many others to manage it.
While under Windows the dialer is automatically invoked when you launch an
Internet application, under Linux the path is the other way round: you dial
first, then launch the application. A thing called diald provides
the usual behaviour. Installing and configuring dialup networking used to be
one of the most difficult things to do under Linux, but not anymore: please
consult the Configuration HOWTO.
Finally, a word about ``Network neighborhood'': you can make your Linux workstation appear as Windows NT/9x in a local network of Windows machines! The magic word is Samba: not the lively Brazilian dance, but an implementation of the SMB protocol for Linux. Go to http://samba.anu.edu.au/samba.
If you used .BAT files to create shortcuts of long command lines (I did a
lot), this goal can be attained by inserting appropriate alias lines (see
example above) in profile or .bash_profile. But if your
.BATs were more complicated, then you'll love the scripting language made
available by the shell: it's as powerful as good ol' QBasic, if not more. It
has variables, structures like while, for, case, if... then... else, and
lots of other features: it can be a good alternative to a ``real''
programming language.
To write a script---the equivalent of a .BAT file under DOS---all you have
to do is write a standard ASCII file containing the instructions, save it,
then make it executable with the command chmod +x <scriptfile>.
To execute it, type its name.
A word of warning. The system editor is called vi, and in my
experience most new users find it very difficult to use. I'm not going to
explain how to use it; please consult Matt Welsh's book or search for a
tutorial on the net. Suffice it here to say that:
i then your text;x;vi whithout saving, type <ESC> then :q!:wq.A good beginner editor is joe: invoking it by typing jstar
you'll get the same key bindings as the DOS/Win editor. jed in
WordStar or IDE mode is even better. Please consult Section
Where to Find Applications to see where to get these
editors.
Writing scripts under bash is such a vast subject it would require
a book by itself, and I will not delve into the topic any further. I'll just
give you an example of shell script, from which you can extract some basic
rules:
#!/bin/sh
# sample.sh
# I am a comment
# don't change the first line, it must be there
echo "This system is: `uname -a`" # use the output of the command
echo "My name is $0" # built-in variables
echo "You gave me the following $# parameters: "$*
echo "The first parameter is: "$1
echo -n "What's your name? " ; read your_name
echo notice the difference: "hi $your_name" # quoting with "
echo notice the difference: 'hi $your_name' # quoting with '
DIRS=0 ; FILES=0
for file in `ls .` ; do
if [ -d ${file} ] ; then # if file is a directory
DIRS=`expr $DIRS + 1` # DIRS = DIRS + 1
elif [ -f ${file} ] ; then
FILES=`expr $FILES + 1`
fi
case ${file} in
*.gif|*jpg) echo "${file}: graphic file" ;;
*.txt|*.tex) echo "${file}: text file" ;;
*.c|*.f|*.for) echo "${file}: source file" ;;
*) echo "${file}: generic file" ;;
esac
done
echo "there are ${DIRS} directories and ${FILES} files"
ls | grep "ZxY--%%WKW"
if [ $? != 0 ] ; then # exit code of last command
echo "ZxY--%%WKW not found"
fi
echo "enough... type 'man bash' if you want more info."
Under UNIX, the system language is C, love it or hate it. Scores of other languages (Java, FORTRAN, Pascal, Lisp, Basic, Perl, awk...) are also available.
Taken for granted that you know C, here are a couple of guidelines for those
of you who have been spoilt by Turbo C++ or one of its DOS kin. Linux's C
compiler is called gcc and lacks all the bells and whistles that
usually accompany its DOS counterparts: no IDE, on-line help, integrated
debugger, etc. It's just a rough command-line compiler, very powerful and
efficient. To compile your standard hello.c you'll do:
$ gcc hello.c
which will create an executable file called a.out. To give the
executable a different name, do
$ gcc -o hola hello.c
To link a library against a program, add the switch -l<libname>. For example, to link in the math library:
$ gcc -o mathprog mathprog.c -lm
(The -l<libname> switch forces gcc to link the
library /usr/lib/lib<libname>.so; so -lm links
/usr/lib/libm.so).
So far, so good. But when your prog is made of several source files, you'll
need to use the utility make. Let's suppose you have written an
expression parser: its source file is called parser.c and
#includes two header files, parser.h and xy.h. Then
you want to use the routines in parser.c in a program, say,
calc.c, which in turn #includes parser.h. What a mess!
What do you have to do to compile calc.c?
You'll have to write a so-called Makefile, which teaches the
compiler the dependencies between sources and objects files. In our example:
# This is Makefile, used to compile calc.c # Press the <TAB> key where indicated! calc: calc.o parser.o <TAB>gcc -o calc calc.o parser.o -lm # calc depends on two object files: calc.o and parser.o calc.o: calc.c parser.h <TAB>gcc -c calc.c # calc.o depends on two source files parser.o: parser.c parser.h xy.h <TAB>gcc -c parser.c # parser.o depends on three source files # end of Makefile.
Save this file as Makefile and type make to compile your
program; alternatively, save it as calc.mak and type make -f
calc.mak, and of course RMP. You can invoke some help about the C
functions, that are covered by man pages, section 3; for example,
$ man 3 printf
To debug your programs, use gdb. info gdb to learn how to
use it.
There are lots of libraries available; among the first you may want to use
are ncurses (textmode effects), and svgalib (console
graphics). Many editors can act as an IDE; emacs and jed,
for instance, also feature syntax highlighting, automatic indent, and so on.
Alternatively, get the package rhide from
ftp://metalab.unc.edu:/pub/Linux/devel/debuggers/. It's a Borland IDE
clone, and chances are that you'll like it.
If you feel brave enough to tackle X11 programming (it's not that difficult), there are several libraries that make writing X11 programs a breeze. The main sites to visit are those of GTK+, http://www.gtk.org, and Qt, http://www.troll.no. Gtk+ is a C-based widget set originally written for the graphic package The GIMP ( http://www.gimp.org), and is used by the Gnome environment. Kdeveloper is based on C++-based Qt, used by KDE. Most likely, you'll use one of these.
Some of the best tools for visual programming are Kdevelop for Qt, http://www.kdevelop.org, and Glade for GTK+, http://glade.pn.org. This page has more information: http://www.free-soft.org/guitool/.
Wouldn't it be nice if you could write code that compiled seamlessly under
Linux and Windows using gcc? As of this writing, there are
some widget sets that allow for more-or-less stable multi-platform
programming. As far as stability and completeness are concerned though, I
would say that the choice is narrowed down to only one: FLTK, the Fast Light
Tool Kit
http://www.fltk.org. It's amazingly small, quick, and
stable. It also has a semi-visual builder called Fluid.
Much more than 1%, actually...
Yes, you can to some extent run DOS and Windows applications under Linux! There are two emulators that are quite good: Dosemu ( http://www.dosemu.org) and Wine ( http://www.winehq.com). The latter is getting better release after release, and the list of runnable applications is getting larger. It even runs Word and Excel!
Under UNIX there are some widely used applications to archive and compress
files. tar is used to make archives---it's like PKZIP or
Winzipbut it doesn't compress, it only archives. To make a new
archive:
$ tar cvf <archive_name.tar> <file> [file...]
To extract files from an archive:
$ tar xvf <archive_name.tar> [file...]
To list the contents of an archive:
$ tar tf <archive_name.tar> | less
You can compress files using compress, which is obsolete and
shouldn't be used any more, or gzip:
$ compress <file>
$ gzip <file>
that creates a compressed file with extension .Z
(compress) or .gz (gzip). These programs can
compress only one file at a time. To decompress:
$ compress -d <file.Z>
$ gzip -d <file.gz>
RMP.
There are also the unarj, zip and unzip (PK??ZIP
compatible) utilities. Files with extension .tar.gz or
.tgz (archived with tar, then compressed with
gzip) are as common in the UNIX world as .ZIP files are under DOS.
Here's how to list the contents of a .tar.gz archive:
$ tar ztf <file.tar.gz> | less
First of all: installing packages is root's work. Most Linux applications
are distributed as a .tar.gz archive, which typically will contain
a directory aptly named containing files and/or subdirectories. A good rule
is to install these packages from /usr/local with the command
# tar zxf <archive.tar.gz>
reading then the README or INSTALL file. In most cases, the application is
distributed in source, which you'll have to compile; often, typing
make then make install will suffice. If the archive
contains a configure script, run it first. Obviously, you'll need
the gcc or g++ compiler.
Other archives have to be unpacked from /; this is the case
with Slackware's .tgz archives. Other archives contain the files
but not a subdirectory - careful not to mess things up! Always list the
contents of the archive before installing it.
Debian and Red Hat have their own archive format; respectively,
.deb and .rpm. The latter is widely used by many
distributions; to install an rpm package, type
# rpm -i package.rpm
Backscrolling: pressing <SHIFT + PAG UP> (the grey key) allows you to backscroll a few pages, depending on how much video memory you have.
Resetting the screen: if you happen to more or
cat a binary file, your screen may end up full of garbage. To fix
it, blind type reset or this sequence of characters: echo
CTRL-V ESC c RETURN.
Pasting text: in console, see below; in X, click and drag to select
the text in an xterm window, then click the middle button (or the
two buttons together if you have a two-button mouse) to paste. There is also
xclipboard (alas, only for text); don't get confused by its very
slow response.
Using the mouse: if you installed gpm, a mouse driver for
the console, you can click and drag to select text, then right click to
paste the selected text. It works across different VCs.
Messages from the kernel: have a look at /var/adm/messages
or /var/log/messages as root to see what the kernel has to tell
you, including bootup messages. The command dmesg is also handy.
If you're wondering whether you can replace your old and trusted DOS/Win application with a Linux one, I suggest that you browse the main Linux software repository: ftp://metalab.unc.edu/pub/Linux. Other good starting places are the ``Linux Applications and Utilities Page'' http://www.xnet.com/~blatura/linapps.shtml, the ``official'' Linux page http://www.linux.org, and http://freshmeat.net.
Linux can do an awful lot of things that were cumbersome, difficult or impossible do to with DOS/Windows. Here's a short list that may whet your appetite:
at allows you to run programs at a specified time;
awk is a simple yet powerful language to manipulate data
files (and not only). For example, being data.dat your multi field
data file,
$ awk '$2 ~ "abc" {print $1, "\t", $4}' data.dat
data.dat whose second
field contains ``abc''.
cron is useful to perform tasks periodically, at specified
date and time. Type man 5 crontab.
file <filename> tells you what filename is
(ASCII text, executable, archive, etc.);
find (see also Section
Directories: Translating Commands) is one of the most powerful and
useful commands. It's used to find files that match several characteristics
and perform actions on them. General use of find is:
$ find <directory> <expression>
$ find . -type l -exec ls -l {} \;
$ find / -name "*.old" -ok rm {} \;
$ find . -perm +111
$ find . -user root
grep finds text patterns in files. For example,
$ grep -l "geology" *.tex
zgrep works on gzipped files. RMP;
^a[^a-m]X{4,}txt$ matches a line that starts with `a', followed by
any character except those in the interval a-m, followed by 4 or more `X',
and ends in `txt'. You use regular expressions with advanced editors,
less, and many other applications. man grep for an
introduction.
script <script_file> dumps the screen contents on
script_file until you issue the command exit. Useful for
debugging;
sudo allows users to perform some of root's tasks (e.g.
formatting and mounting disks; RMP);
uname -a gives you info about your system;
zcat and zless are useful for browsing and piping
gzipped files without decompressing them. For example:
$ zless textfile.gz
$ zcat textfile.gz | lpr
bc, cal, chsh, cmp,
cut, fmt, head, hexdump, nl, passwd, printf, sort, split, strings, tac,
tail, tee, touch, uniq, w, wall, wc, whereis, write, xargs, znew. RMP.
Believe it or not, there are fine tools that provide a UNIX-like environment under DOS/Windows! One is the Djgpp suite ( http://www.delorie.com/djgpp/) for DOS, while Cygwin ( http://www.cygnus.com/cygwin) is a more complex port for Win32. Both include the same GNU development tools and utilities as Linux; you won't get the same stability and performance, though.
If you'd like to have a taste of Linux, try out Djgpp. Download and install
the following files (as of this writing, the latest version is 2.02):
djdev202.zip, bnu281b.zip, bsh1147b.zip, fil316b.zip, find41b.zip,
grep22b.zip, gwk303b.zip, lss332b.zip, shl112b.zip.. Installation
instructions are provided, and you can find assistance on
news:comp.os.msdos.djgpp.
In particular, using bash under DOS/Win is a whiff of fresh air. To
configure it properly, edit the supplied file BOOT.BAT to reflect
your installation, then put these files in your home directory (in the
Windows partition) instead of those provided:
# this is _bashrc
LS_OPTIONS="-F -s --color=yes"
alias cp='cp -i'
alias d='ls -l'
alias l=less
alias ls="ls $LS_OPTIONS"
alias mv='mv -i'
alias rm='rm -i'
alias u='cd ..'
# this is _bprof
if [ -f ~/_bashrc ]; then
. ~/_bashrc
fi
PS1='\w\$ '
PS2='> '
CDPATH="$CDPATH:~"
# stuff for less(1)
LESS="-M-Q" # long prompt, silent
LESSEDIT="%E ?lt+%lt. %f" # edit top line
VISUAL="jed" # editor
LESSCHARSET=latin1 # visualise accented letters
export PS1 PS2 CDPATH LS_OPTIONS LESS LESSEDIT LESSOPEN VISUAL LESSCHARSET
You may come across scores of file extensions. Excluding the more exotic ones (i.e. fonts, etc.), here's a list of who's what:
1 ... 8: man pages. Read them with
groff -Tascii -man <file.1>.
arj: archive made with arj.
dvi: output file produced by TeX (see below). xdvi
to visualise it; dvips to turn it into a PostScript .ps
file.
gz: archive made with gzip.
info: info file (sort of alternative to man pages). Get
info.
lsm: Linux Software Map file. It's a plain ASCII file
containing the description of a package.
ps: PostScript file. To visualise or print it get
gs and, optionally, ghostview or gv.
rpm: Red Hat package. You can install it on any system using
the package manager rpm.
taz, tar.Z: archive made with tar and compressed
with compress.
tgz, tar.gz: archive made with tar and compressed
with gzip.
tex: text file to submit to TeX, a powerful typesetting
system. Get the package tex, available in many distributions.
texi: texinfo file, can produce both TeX and info files (cp.
info). Get texinfo.
xbm, xpm, xwd: graphic file.
Z: archive made with compress.
If you need to exchange text files between DOS/Win and Linux, be aware of
the ``end of line'' problem. Under DOS, each line of text ends with CR/LF
(that is, ASCII 13 + ASCII 10), with LF under Linux. If you edit a DOS text
file under Linux, each line will likely end with a strange--looking `M'
character; a Linux text file under DOS will appear as a kilometric single
line with no paragraphs. There are a couple of tools, dos2unix and
unix2dos, to convert the files.
If your text--only files contain accented characters, make sure they are made under Windows (with Notepad) and not under plain DOS; otherwise, all accented characters will be screwed up.
Yes, you can have for free what would otherwise cost a lot of money!
StarOffice ( http://www.sun.com/staroffice.) is currently the only choice, though Koffice is down the pipeline ( http://www.koffice.org). StarOffice is big and slow, but very good anyway: it offers a lot of functionality not found in Microsoft Office. It can also read and write Word and Excel files, although the conversion isn't always perfect.
Another good package is Corel WordPerfect, a free edition of which is available for download. Need I say more? Go fetch it: http://www.corel.com.
Congratulations! You have now grasped a little bit of UNIX and are ready to start working. Remember that your knowledge of the system is still limited, and that you are expected to do more practice with Linux to use it comfortably. But if all you had to do was get a bunch of applications and start working with them, what I included here is enough.
I'm sure you'll enjoy using Linux and will keep learning more about it---everybody does. I bet, too, that you'll never go back to DOS/Win! I hope I made myself understood and did a good service to my 3 or 4 readers.
Copyright (c) by Guido Gonzato, ggonza at tin.it. This document may
be distributed only subject to the terms and conditions set forth in the LDP
License at
http://www.linuxdoc.org/COPYRIGHT.html, except that
this document must not be distributed in modified form without the author's
consent.
If you have questions, please refer to the Linux Documentation Project home page, http://www.linuxdoc.org
This document is provided ``as is''. I put great effort into writing it as accurately as I could, but you use the information contained in it at your own risk. In no event shall I be liable for any damages resulting from the use of this work.
Many thanks to Matt Welsh, the author of ``Linux Installation and Getting Started'', to Ian Jackson, the author of ``Linux frequently asked questions with answers'', to Giuseppe Zanetti, the author of the book ``Linux'', to all the folks who emailed me suggestions, and especially to Linus Torvalds and GNU who gave us Linux.
Feedback is welcome. For any requests, suggestions, flames, etc., feel free to contact me.
Enjoy Linux and life,
Guido =8-)