Other useful UNIX commands
quota
All students are allocated a certain amount of disk space on the file system for their personal files.
To check your current quota and how much of it you have used, type
% quota -v
df
The df command reports on the space left on the file system. For example, to find out how much space is left on the filesystem which holds the current directory, type
% df .
du
The du command outputs the number of kilobyes used by each subdirectory. Useful if you have gone over quota and you want to find out which directory has the most files. In your home-directory, type
% du
compress
This reduces the size of a file, thus freeing valuable disk space. For example, type
% ls -l services
and note the size of the file. Then to compress services, type
% compress services
This will compress the file and place it in a file called services.Z
To see the change in size, type ls -l again.
To uncomress the file, use the uncompress command.
% uncompress services.Z
gzip
This also compresses a file, and is more efficient than compress. For example, to zip services, type
% gzip services
This will zip the file and place it in a file called services.gz
To unzip the file, use the gunzip command.
% gunzip services.gz
file
file classifies the named files according to the type of data they contain, for example ascii (text), pictures, compressed data, etc.. To report on all files in your home directory, type
% file *
history
The bash shell keeps an ordered list of all the commands that you have entered. Each command is given a number according to the order it was entered.
% history (show command history list)
If you are using the C shell, you can use the exclamation character (!) to recall commands easily.
% !! (recall last command)
% !-3 (recall third most recent command)
% !5 (recall 5th command in list)
% !grep (recall last command starting with grep)
You can increase the size of the history buffer by typing
% HISTSIZE=1000
(This sets an environment variable
M.Stonebank@surrey.ac.uk, © 24th August 2001