CS 112

 File Server

CS

cs.wellesley.edu, also known as puma, is a file server maintained by the Computer Science Department. The department and class web pages are on this machine, as well as accounts for students taking CS classes.

At the beginning of the semester, each CS112 student must request an account. Your account name is the same as your FirstClass account name. You can choose whatever password you like.

Passwords

Your CS112 password should not be anything that someone could guess (like your name, telephone number, or cat's name) or that a computer would find quickly by guessing. It should be at least 6 characters long, should not be a word in any language, and should include at least one character that is not a letter.

Examples of bad passwords: cs112, computer, sesame, abracadabra, Wellesley, Georgia, 092378

Examples of good passwords: 17Abby23, UpAnDdOwN 1nter3net!

Of course, the examples of good passwords are not good passwords any more, because they appear here.

Both account names and passwords are case sensitive, which means that upper and lower case letters are considered distinct.

If you forget your password during the term, please contact your instructor.

Directories

A directory is a structure that contains files and other directories. It corresponds to a folder on a Mac or in Windows. Associated with every CS112 account is a home directory in which files for the account are stored. Whenever you connect to the CS server using Fetch or WinSCP (see below), you will be connected to your home directory.

Different directories have different permissions, which means that you may or may not be allowed to read or write files in them. Obviously, you can both read and write your home directory, but you cannot read or write other students' directories. There are some CS112 directories that you can read but not write.

The name of your home directory is the same as your account name. All home directories on the CS112 server are located within another directory named students, which itself is located in the top-level directory, which is called /.

Directory and file names are often specified as a path name containing the sequence of directories that must be traversed to get from the "top" of the file system to the desired directory or file. Path names are written with the components separated by slash ('/') characters. For example, Georgia Dome's home directory is students/gdome.

Rather than type the entire path to refer to your home directory, you can abbreviate it with a tilde ('~', often pronounced 'twiddle'). The directory ~ is an abbreviation for students/.

The CS112 server file system has been preconfigured with a number of special directories. The following examples are the directories for gdome; you should substitute your own account name:

Permissions

Only you are able to write files to or delete files from your home directory, or any subdirectories thereof. Additionally, only you are able to write files to or delete files from the drop folders with your account name. Any attempt to write files in another students' home directory or drop folders will fail.

Only you are able to read files in your drop folders and your private directory (and subdirectories thereof). However, by default, all directories other than your private directory are world readable, which means that anyone may read them. If you want files to be private, you should store them in your private folder.

Note that your instructors have the ability to read, write, and delete any of your files. However, except under unusual circumstances, the only private files of yours that we will manipulate are those that you explicitly submitted to your drop folders.

Transferring files to the CS server

To transfer files between the CS112 server and your local computer, you need to use a Secure File Transfer Protocol (SFTP) client on your local computer. Fetch is a MacIntosh program that provides SFTP client services, and WinSCP is a similar program for PCs. Information about both of these applications is available from the Wellesley Computing web pages. To connect to the CS server, you will have to provide the following information:

Selecting OK should connect you to your home directory. Once you are connected through your account, you can upload files (copy onto the server), or delete files in your account on the server.

Transferring files (downloading assignments) from the cs server

To download assignments from the cs112 server, you need to access the server by using the special download account, cs112d (the "d" stands for download). To do this, follow the example below:

Selecting OK will connect you as cs112d. You can then select the folder you wish to download by clicking on it once to highlight it. Then you can drag it to your desktop. This account, cs112d, is only to be used for downloading from the cs server.

Quotas

Because storage resources on the cs server are limited, each student account is allocated a limited amount of disk space, known as a quota. If you keep lots of files, or even just a few large ones (such as images), you may find yourself exceeding the quota. An attempt to store a file that will exceed the quota will fail. In this case, you will need to delete some older files in order to be able to store new ones.

Backups

File servers sometimes fail. In some cases, they may become inaccessible for long periods of time; in other cases, they may actually lose information. For both of these reasons, we require you to keep copies of all your work during the semester on your own personal media (copy to a disk, a CD, an iPod, or even email to yourself). That way, if the cs server should become inaccessible or lose files, you will still be able to proceed with your work.

We encourage you to make backup copies of your work on a regular basis during the semester. Since student accounts on the cs server will be deleted after the semester ends, you should be sure to save on your personal media any files from the cs server that you wish to keep for the future.