LIS651%20lecture%205%20direct%20use%20of%20wotan

1
LIS651 lecture 5direct use of wotan

• Thomas Krichel
• 2006-04-29

2
communication with wotan

• For file editing and manipulation, we use putty.
• For file transfer, we use winscp.
• Both are available on the web.
• The protocol is ssh, the secure shell, based
  public-key cryptography.

3
installing putty

• Go to your favorite search engine to search for
  putty.
• If you have administrator rights install the
  installer version.
• Since you have already installed winscp, you
  should have no further problems.

4
putty options

• In the window/translation choose UTF-8, always.
• Find out what the size of your screen is of
  screen that your are using for the font that you
  are using, and save that in your session.
• For wotan, the port is 22, ssh.
• You can choose to disable the annoying bell.

5
issuing commands

• While you are logged in, you talk to the computer
  by issuing commands.
• Your commands are read by command line
  interpreter.
• The command line interpreter is called a shell.
• You are using the Bourne Again Shell, bash.

6
bash features

• bash allows to browse the command history with
  the up/down arrow keys
• bash allows to edit commands with the left/right
  arrow keys
• exit is the command to leave the shell.

7
files, directories and links

• Files are continuous chunks data on disks that
  are required for software applications.
• Directories are files that contain other files.
  Microsoft calls them folders.
• In UNIX, the directory separator is /
• The top directory is / on its own.

8
home directory

• When you first log in to wotan you are placed in
  your home directory /home/username
• cd is the command that gets you back to the
  home directory.
• The home directory is also abbreviated as
• cd user gets you to the home of user user.
• cd does what?

9
/public_html

• Is your web directory. I created it with mkdir
  public_html in your home directory.
• The web server on wotan will map requests to
  http//wotan.liu.edu/user to show the file
  user/public_html/index.html
• The web server will map requests to
  http//wotan.liu.edu/user/file to show the file
  user/public_html/file
• The server will do this by virtue of a
  configuration option.

10
changing directory, listing files

• cd directory changes into the directory directory
• the current directory is .
• its parent directory is ..
• ls lists files

11
users and groups

• root is the user name of the superuser.
• The superuser has all privileges.
• There are other physical users, i.e. persons
  using the machine
• There are users that are virtual, usually created
  to run a daemon. For example, the web sever in
  run by a user www-data.
• Arbitrary users can be put together in groups.

12
permission model

• Permission of files are given
• to the owner of the file
• to the the group of the file
• and to the rest of the world
• A group is a grouping of users. Unix allows to
  define any number of groups and make users a
  member of it.
• The rest of the world are all other users who
  have access to the system. That includes
  www-data!

13
listing files

• ls lists files
• ls -l make a long listing. It contains
• elementary type and permissions (see next slide)
• owner
• group
• size
• date
• name

14
first element in ls -l

• Type indicator
• d means directory
• l means link
• - means ordinary file
• 3 letters for permission of owner
• 3 letters for permission of group
• 3 letters for permission of rest of the world
• r means read, w means write, x means execute
• Directories need to be executable to get in them

15
change permission chmod

• usage chmod permission file
• file is a file
• permisson is three numbers, for owner, group and
  rest of the world.
• Each number is sum of elementary numbers
• 4 is read
• 2 is write
• 1 is excute
• 0 means no permission.
• Example chmod 764 file

16
general structure of commands

• commandname flag --option
• Where commandname is a name of a command
• flag can be a letter
• Several letters set several flags at the same
  time
• An option can also be expressed with - - and a
  word, this is more user-friendly than flags.

17
example command ls

• ls lists files
• ls -l makes a long listing
• ls -a lists all files, not only regular files but
  some hidden files as well
• all files that start with a dot are hidden
• ls -la lists all files is long listing
• ls --all is the same as ls -a. --all is known as
  a long listing.

18
copying and removing files

• cp file copyfile copies file file to file
  copyfile. If copyfile is a directory, it copies
  into the directory.
• mv file movedfile moves file file to file
  movedfile. If movedfile is a directory, it moves
  into the directory.
• rm file removes file, there is no recycling bin!!

19
directories and files

• mkdir directory makes a directory
• rmdir directory removes an empty directory
• rm -r directory removes a directory and all its
  files
• more file
• Pages contents of file, no way back
• less file
• Pages contents of file, u to go back, q to
  quit

20
soft links

• A link is a file that contain the address of
  another file. Microsoft call it a shortcut.
• A soft link can be created with the command
• ln -s file link_to_file where file is a file that
  is already there and link_to_file is the link.

21
file transfer

• You can use winscp to upload and download files
  to wotan.
• If uploaded files in the web directory remain
  invisible, that is most likely a problem with
  permission. Refer back to permissions.
• chmod 644 will put it right for the files
• chmod 755 . (yes with a dot) will put it right
  for the current directory
• is a wildcard for all files.
• rm -r is a command to avoid.

22
editing

• There are a plethora of editors available.
• For the neophyte, nano works best.
• nano file edits the file file.
• nano -w switches off line wrapping.
• nano shows the commands available at the bottom
  of the screen. Note that letter, where letter is
  a letter, means pressing CONTROL and the letter
  letter at the same time.

23
emacs

• This is another editor that is incredibly
  featureful and complex.
• Written by Richard M. Stallman, of GNU and GPL
  fame.
• Get an emacs cheat sheet of the web before you
  start it. Or look at next slide.

24
emacs commands

• (here stands for the control characher)
• xs saves buffer
• xc exits emacs
• g escapes out of a troublesome situation
• controlspace sets the mark
• w removes until the mark (cut)
• y pastes

25
common emacs/bash commands

• k kills until the end of the line or removes
  empty line
• y yank what has been killed (paste)
• a get to the beginning of the line
• e get to the end of the line

26
emacs modes

• Just like people get into different moods, emacs
  gets into different modes.
• One mode that will split your pants is the PHP
  mode.
• emacs file.php to edit the file file in PHP
  mode.
• Then look how emacs checks for completion of
  parenthesis, braces, brackets, and the and use
  the tab character to indent.

27
copy and paste

• Putty allows to copy and paste text between
  windows and wotan.
• On the windows machine, it uses the windows
  approach to copy and paste
• On wotan machine,
• you copy by highlighting with the mouse left
  button
• you paste using the middle button
• if you don't have a middle button, use left and
  right together

28
running mySQL

• You can run mySQL in command line mode in wotan.
  Type
• mysql -u user -p
• You will then be prompted for your password. The
  username and password are your mySQL user name
  and mySQL password, not your wotan user name and
  wotan password.
• Dont forget the semicolon after each command!

29
http//openlib.org/home/krichel

• Thank you for your attention!
• Please switch off machines b4 leaving!