You may have noticed that each time you start Xwindows, a shell window,
similar to a DOS window in Win95/98, appears. This is the powerhouse of the
Linux OS, and from here you can execute copy, compile, move, find and edit
commands just as easily as in dos. Unfortunately, there are different commands
used in the Linux shell than in DOS, so I'll explain them one by one. Remember
that commands are case sensitive in Linux, so LS is not the same command as ls,
and will return an error saying so.
Wiping the screen
To clear a screen full of text, perhaps garbage on a terminal ... just type in
clear from the command line
Finding out what is in a directory
DOS has that nice dir command, but where is the Linux version? It's replaced by
ls. ls, can be remembered as a list (Acronym) of what is in that directory.
It is quite confusing to look at, and its harder to separate what is a folder, what
is a file, and what can be run. In DOS, there are a vast number of switched, or options,
that can be added to the basic command dir to give more information. Linux is not left behind, and adds even more commands to confuse yourself with *grin*. ls -m (remember this as more),
is similar to dir /w, giving horizontal lines of filenames and directory names. ls -l
is a switch that will give the full names of the files, and then give the permissions of the
files (Who is entitiled to execute them), and whether or not they are executable. If an X is present in the attributes, that file is a program, and can be run by typing ./nameoffile.
Files can only be run if they have the ./ prefix before them. The other attributes you will
learn as time progresses and you become more familiar with the Operating System. The best usage of ls, is ls --color. This gives a wide listing, with colors assigned to various file types.
When using this option, directories are in blue, and executables in green. This option is by
far the best. Typing ls --color can get annoying as I found after a while, so its possible to create a text file with 'ls --color' contained, and then allow that file to be executed. By placing
this file in the path, and changing its name to lss, you could use it quite frequently! I will show
how to do this at a later date.
Just as in DOS, the cd (Change Directory) command is used. When the command
shell opens, it opens in your own, home directory, usually 'root'. If you ever
need to return to your own home directory, just enter cd and press return. As
in DOS, to move out one level in a directory tree, type cd .. You can go to the root
directory of your Linux OS and all it's drives by typing cd /. Note how in Linux, there
is a backslash instead of a forward slash. Another thing is that Hard Disks are not
mounted as drive c, drive d and so on. They are placed as folders, and to all intents
and purposes look just like one big hard disk. To find out what disks are mounted, where,
and what capacity they are and have left, type df (I remember this using, disk free, relating
to free space).
If you want to go to one of the user accounts on your machine, you can cd ~username, and that'll take you to where their account resides (Assuming you have permission to enter their directory). Thats about all that command does.
File name completion
The very nice thing about the Linux shell, as opposed to the DOS shell, is that
it can complete file names and directory names for you. The TAB button, located above
Caps-Lock, is the completion key. Once you have typed in the beginning of a file, or
directory, pressing TAB will search for a list of possible file or directory names.
If more than one option is presented, nothing will appear and pressing TAB a second time
will present a complete selection of all that are available, enter a few more characters of
the option you want, and press TAB again.
This is an interesting one. For copying internally between mounted drives, it's very
similar to the DOS syntax. to copy blah.xxx from the current directory to /root/, the syntax is
cp blah.xxx /root/, just remember that if something is going into a lower level directory to give the
full path, including the forward slash.
Moving or Renaming Files
Again, ths syntax is very similar to the DOS syntax. If yout want to rename blah.xxx to xxx.blah, the
command is mv blah.xxx xxx.blah, fairly simple. If you are just relocating the file, remember that two
files with the same name cannot reside in the same directory, so you will have to give a directory name, just
like the description in the Copying section above.
Working with MS-DOS floppy disks
This has to be my favourite shell commandset. Before I learned how to access these properly, I was mounting
floppies, and then unmounting them, which was ridiculous. The Mtools that come installed with RH5.x allow file
This, as I would say, is gruntling! *grin*.
To get a directory from a DOS floppy, shove it in the drive, and from an RXVT shell, whack in mdir a: - thats all
you have to do. It'll list all files with their true DOS names (12345678.123 format), and where possible, give the
long filenames too. To copy from a floppy it's just, mcopy a:\nameoffile /anydiryouwant/, simple as that. To copy
to a floppy, it's similar, mcopy nameoffile a:\anydirthatexsists. And finally, to delete a file, its just a case
of mdel a:\nameoffile.
About the author, Owen Kelly.