Learning Linux

Free resources to learn Linux
  • If you are new to Linux, here are some free resources to learn more. Don't be surprised if we point you to this article if you clearly are new and you are asking lots of good questions.
  • If you are using Glue (UMD centrally managed Linux system), there are a few areas where things are a bit different from general Linux.
    • On a Glue machine, directories can be local or on the file server.   The type of file system used on the file server is the Andrew File System.  This is important to note as permissions and quotas work very differently on the file server than on local storage.
      • Run this command to see if the directory you are viewing is on the file server
        • fs examine <directory name>
          • If the result is "fs: Invalid argument; it is possible that /<directory name> is not in AFS.",
    •  Permissions
      • In Glue, anything that is on the file server has different permissions than standard Linux permissions.
      • If the directory is on the file server, then you can run these commands to see the permissions.
    • Quotas
      • In Glue, anything on the file server has a quota and the quotas work differently from standard Linux quotas.  
      • To list the quota for a directory, use the command below which will list the quota and usage in a human readable form (G = gigabyte instead of seeing lots of numbers that you have to interpret). 
        • fs lq -human <directory> 
      • Generally, you can't request much additional quota without paying for the space.  If you have local storage available (many times this is located in /export/<your username>, you can use that either by putting data/software there directory or by using Linux symbolic links from your home space to point to local space you have access to.
      • Example
        • ln -s /export/<your username>/<what you want to point to> ~<your username>/<what you want to point from>

Keywords:
ubuntu redhat red hat unix 
Doc ID:
154940
Owned by:
Jeff M. in Engineering IT
Created:
2025-09-19
Updated:
2025-09-19
Sites:
University of Maryland Engineering IT