File Systems, telnet and ftp

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File Systems, telnet and ftp

• Sources and Resources
• A Students Guide to UNIX, by Hahn
• Paula Davidsons Handout on UNIX

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Internet Applicationstelnet For Remote Login

• telnet remote_host_name
• Internet application
• Used to login to a remote computer
• Allows your expensive PC to look like a dumb
  glass tty or asynchronous terminal
• At UNCA, you will use telnet to login to the
  servers bulldog.unca.edu, candler.cs.unca.edu,
  and the engineering server.engr.unca.edu

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Internet Applicationstelnet For Remote Login

• Ways to access telnet
• From a DOS window
• From the run window in Windows
• From a browser
• telnet//login_name_at_server_name
• telnet//reiser_at_candler.cs.unca.edu

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Internet Applicationsftp For Moving Files

• ftp remote_host_name
• Internet application
• Used to move files to or get files from a remote
  computer
• At UNCA, you will use ftp to move files to the
  servers bulldog.unca.edu, candler.cs.unca.edu,
  and the engineering server.engr.unca.edu

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Internet Applicationsftp For Moving Files

• Ways to access ftp
• From a DOS window
• From the run window in Windows
• From a browser
• ftp//login_name_at_server_name
• ftp//reiser_at_candler.cs.unca.edu
• What would happen if you used
• ftp//candler.cs.unca.edu

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UNIX File System

• Hierarchical
• Contains files
• Text files
• Special files
• Standard I/O Keyboard, Display
• Device files
• Directories

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File Structure - Hierarchical
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Paths

• Relative
• newDirectory
• newDirectory/myFiles/homework1.doc
• Absolute
• /usr/users/reiser/newDirectory
• /usr/users/reiser/newDirectory/myFiles/homework1.d
  oc

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Commands mkdir

• Make a directory
• mkdir newDirectory
• Makes a new directory named newDirectory as a
  child of the current directory

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Commands rmdir

• Remove a directory
• rmdir newDirectory
• Removes a directory named newDirectory.
• If specified as a relative path (not beginning
  with a /) the directory to be removed must be in
  the current working directory.

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Commands ls

• List contents of a directory
• ls newDirectory
• Lists the contents of newDirectory
• ls
• Lists the contents of the current working
  directory
• ls a
• Lists all the contents of the current working
  directory, even the hidden files

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Commands ls

• List contents of a directory
• ls l
• Lists all the contents of the current working
  directory in a long listing which displays the
  file permissions as well as the owner, group,
  size in bytes, modification date

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Commands cd

• Change directory
• cd // sets current working directory
• // to your home directory
• cd otherDirectory
• // sets current working directory
• // to otherDirectory

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Commands cd

• Change directory
• cd .. // sets current working directory
• // to the parent directory or moves
• // one level up the hierarchy
• cd ../..
• // sets current working directory
• // to 2 levels up the hierarchy

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Commands mv

• Move or rename a file
• mv file1.txt file1.html
• // renames file1.txt to file1.html
• mv file1.txt newDirectory/file1.html
• // moves file1.txt to newDirectory/file1.html

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To do

• telnet into your account
• Display your home directory. What directories
  exist in your home directory?
• Do you have a public_html directory?
• If not, create a directory under your home
  directory and call it public_html

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To do

1. Change directories into your public_html
   directory.
2. Change back to your home directory.
3. Change to the root directory.
4. Change back to your home directory.
5. Create a subdirectory called junk
6. Change into junk and create two subdirectories
   j1 and j2.
7. Remove j1, j2 and junk.

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File Permissions

• The various flavors of UNIX including LINUX and
  OS/X store permissions for every file.
• There are three independent permissions
• Read
• Write
• Execute
• You can change permissions for your files.

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File Permissions for Directories

• The various flavors of UNIX including LINUX and
  OS/X store permissions for every directory.
• There are three independent permissions
• Read - read names in a directory
• Write - make changes (create, move, copy, remove)
• Execute - search the directory (cd into it)
• You can change permissions for your directories.

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Permissions an octal representationchmod
permissions file

• Read 4 100
• Read Write 6 110
• Read Execute 5 101
• Read Write Execute 7 111
• Write 2 010
• Write Execute 3 011
• Execute 1 001

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chmod permissions file

• Each file has three sets of permissions
• Permission modes exist for
• you your_group world
• rwx rwx rwx
• chmod 777 myWideOpenFile
• chmod 744 myOtherFile
• chmod 700 mySecretFile

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Displaying File Permissions

• ls -l
• -rw-r--r-- 1 mmasuser staff 20788 15 Dec
  1414 Adobe SVG 3.0 Installer Log
• drwx------ 19 mmasuser staff 646 21 Jan
  1453 Desktop
• drwx------ 21 mmasuser staff 714 16 Jan
  1513 Documents
• drwx------ 29 mmasuser staff 986 11 Nov
  1409 Library
• drwx------ 17 mmasuser staff 578 27 Nov
  1955 Movies
• drwx------ 4 mmasuser staff 136 9 Oct
  1352 Music
• drwx------ 5 mmasuser staff 170 19 Dec
  1927 Pictures
• drwxr-xr-x 4 mmasuser staff 136 9 Oct
  1330 Public
• drwxr-xr-x 5 mmasuser staff 170 9 Oct
  1330 Sites

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In class

• Do you have a directory under your home directory
  named public_html?
• If not, create a directory under your home
  directory and call it public_html
• Set file permissions for public_html
• chmod 755 /public_html
• Change directories into your public_html
  directory. Create a new directory named 172.
• Create 3 subdirectories of 172 Assignment1,
  Assignment2, and Assignment3.