First Steps Using johnny.sas

Logging in to johnny.sas

• To login from a Microsoft Windows Computer:
  Download and install the (free) software SecureCRT, available from: Download SecureCRT
  Then use it to login to: johnny.sas.upenn.edu [SecureCRT uses "ssh" to encrypt everything between your computer and johnny.sas, so evesdroppers can't see what you are doing.]
  The SecureCRT screen you get by default may not have johnny.sas so instead, at the top of the window, click on the second icon from the left (it will say: "Quick Connect"). In the new window that pops up use:

        Protocol:  SSH2
        Hostname:  johnny.sas.upenn.edu
        Username:  [insert yourPennNet Id]
        (and use the remaining default settings)

• To login from Macs & Linux computers
  Since Macs are born as Unix computers, Mac & Linux users can simply open a Terminal window and use ssh directly by giving the command
  ssh [PennNetId]@johnny.sas.upenn.edu
  where you replace "[PennKey]" with your own PennKey UserId.

• Changing your password on johnny.sas
  You should change your password immediately. To do so, after you login to johnny.sas, give the command:
  passwd
  and answer the questions it asks about your old and new passwords.

Make Your Own Home Page

• Change to your html directory with the command:
  cd   html

• To edit a file, say test.html, use "nano" editor with the command
  nano   test.html
  At the bottom of the nano screen are various commands that nano understands, for example "^G Get Help" means use "Control G" to get help. Note that using ^O you can save your file and continue editing, while with ^X you can save the file and EXIT immediately.

• To give others permission to read -- but not write -- this file, use the command chmod to change the permissions as follows:
  chmod   644 test.html
  Of course, replace test.html with the name of your own file. The URL to access this file is
      http://johnny.sas.upenn.edu/~YourUserId/test.html
  where replace "YourUserId" by your userid on johnny.sas (which apppens to be your PennKey). The filename index.html is special. If you give this for the name of your home page, then you are allowed to use the shorter URL:
      http://johnny.sas.upenn.edu/~YourUserId/
  since the computer knows to automatically read your index.html file.

• NOTE: if you write a program, such as a perl script, you need to tell the computer it is a program by making it executable. For this use:
  chmod   755 dice.pl
  As always, replace dice.pl with the name of your own program. With these permissions, only you can edit the program but anyone can read and execute it. Use the permissions 700 if you don't want it accessible by anyone else.

Make A New Directory

• Make a new directory, say named Math210, to put your own perl programs. For this use the command:
  mkdir   Math210

• Change the Permissions: Directories have the same permissions as programs. They need to be executable:
  chmod   755 Math210
  (For other directories you can use the permissions 700 if you don't want it accessible by anyone else.

• To move a file, say named test.pl in your home directory to this new directory give the command:
    mv test.pl Math210

Three Basic Unix Commands

ls (directory listing),   rm (remove a file or directory),   chmod (change permissions of a file).
Caution: Unix commands and file names are case sensitive