New admins will be allocated [[virtual machines|Thrall-#]] before being allowed work on the real cluster. Access to ther outside internet is blocked from these machines. To get at the web you must set the http_proxy environment variable.

$ export http_proxy=""

Only a very brief summary of commands is given here. To get the full manual for these commands, use:

$ man <commandname>

for example to get the manual for ls use:

$ man ls

To get basic help for a command use the argument --help or -h

$ ls --help

Unix Filesystem layout

[WWW] <- far better than my explanations (read this)

File permissions

File permissions in unix are bases on 3 tuples associated with each file or directory.

Each tuple is made up of 3 characters, r(for read), w(for write) and x(for execute). A file/directory has a tuple for the user that owns the file, the group that owns the file and everyone else.

A file has the permissions rwxr-xr--. This means the user can read, write and execute it, the group can read or execute it and others can only read from it.

An important point to note is that if a directory doesn't have it's executable permission set, you will not be able to list the files in it.

Shell redirection

The characters > < and | are very useful on linux commandlines. {{ $ command > myfile - will send the output of command to myfile $ command < myfile - will read input for an application from myfile $ command1 | command2 - will send the output from command1 to command2 }}

Filesystem related commands

Process related commands

Networking commands

Debian specific commands

last edited 2006-07-05 13:24:33 by 193