Bellevue University CIS 240

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Bellevue UniversityCIS 240
Final Review
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The test

• Monday, Dec 11, 2002 at 100PM
• 50 Question multiple choice, True/False, and fill
  in the blanks
• gt1.5 minutes/question (90 minutes total)
• Closed book, closed notes, open computer, closed
  communication between students (for test)
• Practical portion will include connecting to an
  NFS share and downloading a tar.gz file to your
  machine. Gunzip, untar, compile, and run the file
  and record the results on the paper.
• About 30 minutes allowed for the practical.

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Scoring

• 2 points for each correct answer
• If the entire class gets a question wrong, it
  will be thrown out and 2 points will be credited
  to each student

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What will be tested

• Processes
• The network file system
• Sending messages (not tested extensively)
• Using E-Mail (not tested extensively)
• Backing up files
• Transferring files

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What is a Process?

• Executable code
• Data
• Open files
• Stack space

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Viewing processes

• ps is used to view the status of processes
• ps gives you the following information
• Process ID
• Terminal ID of owner
• State
• Running Time
• Command name

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Example

• ps
• PID TTY TIME CMD
• tty1 000000 bash
• 9982 tty1 000000 ps

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Killing a process

• kill is used
• Must be root or process owner to kill it

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Example

• ps
• PID TTY TIME CMD
• tty1 000000 bash
• tty1 000000 ps
• tty1 000000 vi
• kill 9983

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Foreground vs Background

• Foreground processes
• no access to shell while the command is executing
• Background processes
• Access to shell while command is executing
• Run at lower priority then foreground processes

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Format for Running a Background Process

• ltcommandgt

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More options for ps

• -A Displays information about all processes
  running on your system
• -e Same as -A
• -l Displays a long list of of processes that
  includes a 14 column status report
• -u Displays information about processes
  belonging to users

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Stopping and restarting background processes

• Use jobs to identify the job number of the
  background process
• Use fg ltjob numbergt to bring it to the
  foreground
• Use ltctrlgt z to pause it
• Use fg ltjob numbergt to resume it
• Use bg to return it to the background

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daemons

• System processes
• Running in the background
• Can be viewed by entering ps ?A
• daemons will have a question mark for a TTY
  identifier

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What will be tested

• Processes
• The network file system
• Sending messages (not tested extensively)
• Using E-Mail (not tested extensively)
• Backing up files
• Transferring files

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Network File System

• Allows files on remote computers to be accessed
  as though they reside on a local computer
• Operates on the client server model

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Client Server Model

• Server makes the file system available and
  controls access to it
• Client mounts the server?s file system as part of
  its own
• Client and server directories can be different
  (usually are different)

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NFS on the server

• The server must be running the following daemons
  (RPC, portmap, biod, mountd, nfsd)
• The server must make files visible to remote
  systems (using /etc/exports file)

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NFS on the client

• The client must be running the RPC, portmap, and
  biod daemons
• The client mounts the remote file system using
  the mount command

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Adding a file system (won?t be tested
extensively)

• Use vi to edit the /etc/exports file
• Add a line for each file system to be shared
• Format
• ltdirectorygt ltauthorized usergt
• Example
• /home/export 10.0.3.43

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NFS

• Once mounted, filesystem is subject to the
  permissions assigned by the server

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The mount Command

• Adds a new file system to the directory
• Allows other devices (floppy/cd rom/ etc) to be
  accessed by linux
• Allows file systems to be mounted from other
  computers using the Network File System
• Note You must create the filesystem before you
  can mount it

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Creating a file system

• mke2fs /dev/fd0 1440

size
command
path
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Format of mount command

• mount ?t ext2 /dev/fd0 /mnt

type
device
path
command
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unmounting

• Unmounting removes the file system from your file
  structure.
• It is done when you intend to remove the media
  containing the file system from the computer.
• Note You must unmount a file system before you
  remove the floppy from the device. Failure to do
  so can render the files on the floppy
  inaccessible

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umount

• Format
• umount ltpath name of devicegt
• Example
• umount /dev/fd0

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Mounting an MSDOS Floppy

• mount ?t msdos /dev/fd0 /mnt

Type of file system is MSDOS
Note Floppy diskette must be formatted with
MSDOS filesystem
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What?s Mounted?

• To view what you have mounted, use the mount
  command by itself.
• Format
• mount

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Issues

• The server can give a client complete access to
  its file system (security issue)
• If the server goes down while the client is
  mounted to the NFS filesystem, the client can
  (and usually does) lock up

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What will be tested

• Processes
• The network file system
• Sending messages (not tested extensively)
• Using E-Mail (not tested extensively)
• Backing up files
• Transferring files

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One-way real-time message

• Use the write command to send a one-way message
  to another user.
• Both of you must be logged into the same computer
• Both of you must have messaging turned on

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write

• Format
• write ltusergt
• Your message goes here
• ltCtrlgtd

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Using write

• Use who to see who is logged on
• Enter the write command
• After pressing enter, type your message
• When you are finished, type control d to exit and
  send your message

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If write does not work

• The user you have selected may have messaging
  turned off
• Messaging can create problems, and users turn it
  off if it becomes objectionable
• Users may turn messaging on or off using the mesg
  command

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mesg

• Format
• mesg ltoptiongt
• Option Description
• y Grant permission to other users to send
  messages to your terminal
• n Deny permission to other users
  to send messages to your terminal

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What will be tested

• Processes
• The network file system
• Sending messages (not tested extensively)
• Using E-Mail (not tested extensively)
• Backing up files
• Transferring files

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mail

• Covered in Chapter 10 of your book
• The basic program that everybody has
• Command line interface
• Not based on vi

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Using Mail

• Format
• mail ltrecipientgt
• Example
• mail jrussell (to send a message)
• mail (to check your mailbox)

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Process for sending mail

• Enter mail ltrecipientgt
• Enter subject
• Enter message text
• Enter addresses for courtesy copies
• Send message

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Process for reading mail

• Enter mail
• Enter the number of the message you want to read
• Enter d and the number of the message to delete
  it after reading
• Exit with q to remove messages from mailbox

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A Few Basic Commands

• Help ? Prints command summary
• Edit e Edits a message
• Exit x Quits without saving
• Quit q Quits with a save
• Delete d Deletes a message
• List f Lists messages

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What will be tested

• Processes
• The network file system
• Sending messages (not tested extensively)
• Using E-Mail (not tested extensively)
• Backing up files
• Transferring files

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Tape Archive Utility

• Command is tar
• tar can be used to back up and restore files
• tar puts all files and directories into a single
  archive file.
• Files are compressed when they are stored
• Files can be backed up to a device or a directory

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tar

• Format
• tar ltoptionsgt ltarchivegt ltfile(s)gt

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Options

• c Create an archive file and add files to it
• r Record files at the end of the archive
  (append)
• t List the contents of an archive file
• u Update by adding new or changed files
• x Extract files from archive (restore)
• v Verbose mode
• f ltarchivegt name of archive file

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Archive

• Can be device, such as tape backup,
  recordable/rewritable CD ROM, or floppy
• Can be a path name on an existing mounted device

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file(s)

• Relative or absolute path name of files
• Must be specified for backup (tar responds with
  ?Cowardly refusing to create empty tape archive??
  error message if you don?t)
• A period indicates all files at the current
  location are to be backed up.
• Default for restore operation is all files in the
  archive.

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Backup

• Example
• tar cvf archive1.tar .
• Backs up all files in the current directory to
  archive1.tar. Provides a complete list of backup
  operations.

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Restore

• Example
• tar xvf archive1.tar
• Restores all files and directories in
  archive1.tar to the current directory

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View

• Example
• tar tvf archive1.tar
• Prints a list of all files and directories in the
  archive.

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Tips

• Case is important
• Spaces are important
• Using an incorrect option will cause
  unpredictable results
• ltCtrl Cgt will break you out of tar

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Other uses for tar

• Files can be combined for uploading or
  downloading and compressed using gzip (transfer
  multiple files with one command)
• Individual files can be compressed using gzip and
  stored in tar format on a server to reduce the
  amount of space they take up

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Using tar with a floppy diskette

• Works with or without a file system.
• Diskette without a file system cannot be mounted.
• I recommend you use mke2fs to create a Unix file
  system, then mount the device before archiving to
  it.

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What will be tested

• Processes
• The network file system
• Sending messages (not tested extensively)
• Using E-Mail (not tested extensively)
• Backing up files
• Transferring files

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File Transfer Protocol (ftp)

• Utility program for moving files between
  computers
• Named after its underlying protocol
• Implemented with ftp program on client and ftpd
  daemon on the server

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ftp

• Format
• ftp lthost computergt
• Where lthost computergt is a host name or IP
  address
• Example
• ftp academic2.bellevue.edu

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Requirements

• Connection between you and the host computer
• Host must be set up as an ftp server
• Must have an account on the host or host must
  allow anonymous login

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Anonymous Login

• User ID is anonymous
• Password is your E-Mail address

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Commands

• ls View files on host computer
• cd Change directory on host computer
• ! Execute a command on a local computer
• put Move a file from local to host computer
• get Move a file from host to local computer
• close Close the current ftp session
• quit Exit out of ftp
• ? Help