NIU Department of Mathematical Sciences
Managing Disk Usage

Even though our system has plenty of disk space, that space is finite. A disk filling up to capacity is an unpleasant event which can lead to loss of data. Most importantly, excessive disk use can interfere with the regular backups we run. There are many other arguments in favor of cleaning up your files now and then. By following the hints listed below, you will earn gratitude of your fellow users and the system manager.

  1. Remove LaTeX byproducts (.dvi, .aux, .toc, .log files) if you have the TeX source file, and you don't need to print the file any time soon. Use wildcards, e.g. rm *.dvi, but do so with caution -- it will remove all files ending with `.dvi' without asking. There is also an alias cleanup which removes all such files in the current directory.
  2. Go through your mailbox and delete messages you don't need. This will also improve the performance of the mail program you use.
  3. Remove PostScript files which you can easily recreate (e.g. from .fig graphics files or TeX documents). PostScript files tend to be big.
  4. Remove Fortran and C object files (.o) and executables which can be recompiled and which you don't need right now. It takes only a few moments to recreate them. Use the -s option when linking larger programs (or use the `strip' utility) to remove unneeded objects from them.
  5. Compress rarely used files (especially text files) with gzip file. This will create `file.gz', which can then be uncompressed with gunzip file.gz. This often cuts the size by 50% or more, especially in case of text files.
  6. Delete files which have been lying around for months if the chance of them being needed again are low. Such files have certainly been backed up to tape several times; some of those tapes are kept indefinitely. The administrator can get them back if necessary.
  7. If you use S-Plus, you probably have accumulated many files in your .Data directory, and a lot of diagnostic output in the file .Data/.Audit. Remove the data files you no longer need, and truncate the .Audit file by doing the following: cd ~/.Data ; tail -50 .Audit >! .Audit.bak ; mv .Audit.bak .Audit
  8. Bigger collections of files which won't be needed soon should be designated for archival storage. Contact the system manager and ask him to dump the files to tape and to delete them afterwards. Or, if you prefer, bring a recordable CD-ROM, and a copy of the files you specify will be put on it.
  9. If you do need to work with a large amount of data/software, ask for temporary extra storage on one of the computers (with the understanding that the files won't be there `forever', that they will not be backed up regularly, and will be available on that machine only).
  10. Image files (.gif, .jpeg) are usually very large, and cannot be compressed much. Avoid storing them on the system for extended periods of time.
  11. Don't keep your own copies of utility software. If you find a package which might be useful to others, tell the manager about it; in most cases he'll be able to install a publicly accessible copy on the system.
To find large files use a variant of the following command:
find . -type f -size +200000c -mtime +30 -print | xargs ls -l
This will show all files in the current directory (and subdirectories) which are 200 KB or larger and haven't been modified in 30 days.

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