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UNIX is an operating system employed in different forms on a variety of computers. Specifically for Pratt, the Linux form is used on the public computers in the Teer Building. A tutorial is available.


Portions of this FAQ were published by the Student Government and were contributed by the 2008/2009 Senior Class President, Alex Gorham.

What should I do if the computer says that firefox is already running?

Remove the lock file with the commands:

cd   ~/.mozilla/firefox/*.default 
rm   .parentlock

What should I do if I cannot login due to an overfull directory?

You will likely need to clean up your directory. To log in, you can either use MobaXterm for Windows or X11 for Macs to log in remotely or, from a terminal, click the ‘Session’ icon, check ‘Failsafe Terminal’, and login. You will then need to clean things up as described below.

How do I know how much space I have?

  • 8/21/2016: The quota command is gone, so this is a little harder than it used to be. More information soon.

How do I know how much space things take up?

ls -l
Lists the files and folders in a directory as well has how much space those files take. The number next to a directory name is how much space it takes to store the information about the directory, not how much storage the directory's contents take up.
du -ks
Reports the disk usage of the current folder. The k tells UNIX to report the size in kilobytes and the s tells UNIX to summarize for the entire folder rather than showing the storage for each entry in the folder.
du -ks *
Reports the disk usage for each item in the current folder. As above, the k tells UNIX to report the size in kilobytes and the s tells UNIX to summarize - but the addition of the * as an argument means to summarize for each file and folder.
du -ks .??*
Same as above, but looks at hidden files and folders with at least two characters after the "." This means du will skip the "." and ".." shortcuts but will look at anything three characters or more. Often, the directories taking up the most room will be hidden ones, such as .mozilla and .Trash

How do I get rid of things?

Once you know what files and folders are taking up room, determine if you actually need them. If you can remove them, change into their directory and remove them. Be careful - remember, UNIX does not have much by way of an "undo" feature. The cd filename command will allow you to change the directory, and the rm -i filename will interactively remove files. rm -ir directory will interactively remove files from directories and then remove the directories themselves, if empty.


Post your questions by editing the discussion page of this article. Edit the page, then scroll to the bottom and add a question by putting in the characters *{{Q}}, followed by your question and finally your signature (with four tildes, i.e. ~~~~). Using the {{Q}} will automatically put the page in the category of pages with questions - other editors hoping to help out can then go to that category page to see where the questions are. See the page for Template:Q for details and examples.

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