Unix Presentation - CS-People by full name

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					Unix Commands

    Monica Stoica




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            Introduction to Unix
   Unix was born in 1969 at Bell Laboratories, a research
    subdivision of American Telephone and Telegraph
    Company.
   Unix system has two kinds of software:
     the operating system software
     the application software like pico, pine, emacs, etc.

   Some of the functions of the Unix operating system are:
     it provides a filing system (write, copy, rename, move files)
     it provides for the loading and executing of the user
      programs
     it provides a communication link between the computer
      and its accessories (input-output devices as terminals,
      printers, disks, etc).
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Additional Features of
the Unix System
      Multi-user time-sharing
        several people at different
         terminals can use the computer at
         the same time.
      Multitasking
        one user runs several computing
         jobs simultaneously




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             Unix Shell
   The Unix shell is a command line interpreter, or a
    program that forms a link between users and the
    computer.
   The shell accepts commands that you type into the
    computer, and then it executes them.
   The shell contains over 100 built-in commands for
    your use. At the shell % prompt you can type your
    commands.
   There are 2 widely used shells:
     Bourne    shell provided with the standard Bell Labs version
      of Unix
    C   shell developed at the University of California, Berkeley
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              Changing the prompt
   If you got tired of the (login) %
    prompt, you can type set
    prompt=“Any message you
    want ” and every time you
    come back to the shell prompt
    your message will show up
    instead of the (login) %.
   Unix will reset this back to
    (login)% when you logout.
   Make sure you leave a space
    between the end of your
    message and the ending “.
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TIPS
          In case the backspace key does
           not work when you try to erase
           something at the Unix prompt,
           try pressing simultaneously
           Ctrl-h . It will erase one typed
           character every time you press
           it.
          Do NOT put spaces, capital
           letters or unusual characters (as
           !) in file names.
          For more information on a
           command type man command.
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    Password
   If you want to change your password, type
    passwd at the (login) % prompt. You will
    be prompted to enter your old password,
    the new password, and to retype the new
    password.
   You should have at least one digit in your
    password.
   When you choose your new password
    remember that Unix is case-sensitive and
    even a space is considered a character.


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          Finding the time, date and
          calendar of any year
   If you type date at the (login) % prompt, you will
    get the date of the current day, the day of the
    week, and the current time.
    If you type cal 03 1776 at the shell prompt, you
    will get the calendar of the March, 1776. If you do
    not enter a month (that is, you type only cal year)
    you will get all twelve months of that year.
   Tips:
      you can type cal month year of your birth and find
      out what day of the week you were born!
     the year should be in the range 0-9999 AD.



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              The who command
   Since Unix is a time-sharing system, several people can
    use the system at the same time.
   By typing who you will get a list with all the people logged
    in at that moment. The leftmost column shows the
    terminal at which the person is working, the next column
    shows the date and the rightmost column shows the
    computer number (IP number).
   If you type who am I you will get information about
    yourself. You can also use this command in case
    somebody forgot to logout of unix and you want to know
    who that person was.
   Typing who > turkey will create a file called turkey and
    write on it all the information listed as a result of the who
    command. You can type cat turkey to view the file.

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                The finger command
   General form: finger option argument
   finger command without an argument gives the same
    result as who command, but also gives the full name
    of each person. It also gives the idle time in minutes
    since the person last gave a Unix command.
    Adding the option -m obligates finger to look only for
    those people who’s login names match the argument
    name. For example finger -m smonica will search for
    only the people who’s login name is smonica.
   Option -l forces finger to give the results in long
    format, and the option -s to give it in short format.

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More on finger command
       If you want to find out all the
        people with the name or login john
        who have an account in Unix, type
        finger -s john or finger -l john
        depending on whether you want a
        short form or along form. It will
        search for all the people who’s first
        name, last name or login is john.


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         Sending e-mail fast without
         opening pine
   At the (login) % prompt type mail login
    (the login of the person you want to send
    an email). Press Enter.
   Then type Subject: here type your
    subject. Press Enter and type the
    message you want to send.
   When you are done type Enter and then
    Ctrl-d, and you should get a (login)%
    prompt.



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    Files and Directories
   While working with files and directories it will
    help if you think about Unix as a big tree. All
    directories in Unix stem from / , also called root.
   One of root branches is called course for
    students’ directories. All users’ home directories
    stem from course.
   On the next pages you’ll learn how to create
    directories and files, move or copy files from one
    directory to another, and much more.


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           The ls command
   General form: ls option argument. Some of the
    options are:
     -c lists by last change
     -l lists in long format, giving links, owner, size in
      bytes, and time of last file change
   typing ls -l directoryname will list all files and
    subdirectories of that directory in long format.
   Typing only ls will give the current working
    directory.


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      The ls command
   The information on the leftmost part shows the
    permissions of read, write and execute on each
    listing.
   If the first character is a d, it means that is a
    directory. A hyphen - indicates a file.
   The next three characters show the
    permissions of the owner on that file or
    directory, the next three the permissions of the
    group the owner belongs to, and the last three
    characters show the permissions of the rest of
    the world on that file or directory.
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    Example of an ls command result
   This is an example of an ls command result:
   -rwxr-xr--
   The first hyphen - shows that this is a file
   the next three letters rwx show that the owner has
    read, write and execute permission on that file,
   the next group of three r-x show that the group the
    owner belongs to has only read and execute
    permission
   the last three r-- show that the rest of the world has
    only read permission on that file.
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            The cat command
   general form: cat argument
   The cat command is used to concatenate and
    display files. Concatenate means to link together.
   Typing cat file2 will display on the screen file2
    assuming that this file2 already exists.
   You can use cat > newfile to create a new file and
    to enter text into it.
   You can use cat file2 file3 >> file4 to append file2
    and file3 to the end of the file4. If file4 does not
    exist, it is created now to receive the input from
    file2 and file3.
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The wc word count command
        General form: wc option argument
        example: wc file2 will list from left
         to right the number of lines, words,
         and characters of file2.
        options:
          -w  counts only words in a file
          -c counts only characters in a file
          -l counts only lines in a file



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                     Copy Command
   General form1: cp option argument
   cp file1 file2 creates a copy of file1 and gives it the
    name file2. If a file named file2 already exists, it will
    be replaced by the new one.
   Options:
     -i protects you from overwriting an existing file by
      asking you for yes or no before it copies a file with an
      existing name.
     -r can be used to copy directories and all their
      contents into a new directory
   General form 2: cp file1 file2 directory
     thiscopies the list of the files given into the directory
      which must already exist. The originals are kept in
      place.                                         Jump to first page
            The Move Command
   The mv command lets you change the name of a file
    or directory and lets you move a file from one
    directory to another.
   mv file1 to file2 will change the name of file1 to file2.
    The file itself is unchanged. If a file named file2
    already existed, it will be replaced by the content of
    file1. Same thing applies for directories (mv
    directory1 directory2).
   Option -i: it will ask you before it copies to a file with
    an existing name.
   You can move files to an existing directory by typing:
    mv file1 file2 directory
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Differences between cp and mv
         The cp command creates a new
          file with a new ID number and with
          its own link (name) to a directory.
          The old file continues to exists.
         The mv command creates new
          names for the existing files and
          dumps the old names. It does not
          create a new file.


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The rm command
        If you want to remove a
         file, type rm file
        Once that you removed
         it, it’s gone for good.

        This is the end of the
         presentation!



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posted:3/20/2013
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