Miscellaneous Information

Here are all the topics that didn’t fit elsewhere, namely:

  • Monitoring disk usage (df and du)
  • Compressing files (gzip and compress)
  • Converting Postscript to PDF format (ps2pdf)

Monitoring disk usage

To see how much free disk space is currently available on the file system where you reside, use the following command:

df $HOME

You can see how much you yourself are using with the command:

du $HOME

This may take a while if you have many files. To see how big an individual file is, use the command

ls -s file

All these commands measure disk space in “blocks” of 512 bytes. Divide this by two to get usage in Kilobytes.
If you are using a lot of disk space, please remove files that you don’t need. Files called core, those ending in .o, and some .ps and .dvi files are frequently created but not needed. Files you do still need, but not right now, can often be compressed, as described below.


Compressing files

One way to reduce your disk usage is to “compress” large files that you may still need, but which you don’t use every day.

There are many programs for doing this, of which the most common is probably gzip, and its opposite, gunzip. To compress a file called fred, use the command

gzip fred

This will create a file called fred.gz that is the compressed form of fred; the original file is removed. Compressed files are often half the size of the original, or less, though it is possible, but rare, for the “compressed” file to actually be slightly larger than the original.

The compressed file will look like garbage. To get back the original when you need it, use the following command:

gunzip fred.gz

This recreates the original file fred, and removes fred.gz.

See “man gzip” for more details.

You can also compress and uncompress files with the compress and uncompress programs. Files compressed in this way conventionally have names ending in “.Z”.

Converting Postscript to PDF format

The ps2pdf program converts a document in Postscript format to one in PDF format. This is useful for putting documents up on you web page, since many people can view documents in PDF format but not in Postscript format.

The format of the command is just

ps2pdf input-file.ps output-file.pdf

See “man ps2pdf” for details.

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