Manage the dwww cache of converted documents
dwww-cache --lookup type location
dwww-cache --store type location
dwww-cache --list type location
dwww-cache manages the cache of converted documents; it is part of dwww(7). An option (the first argument) specifies the operation. Some operations operate on the whole cache, and need no other arguments. Others need the second and third argument to specify the type and pathname of the original document. (See dwww-convert(8) for more information about the arguments.)
The operations are:
If the document is in the cache, output it to the standard output. Otherwise, output nothing and return a non-zero status.
Read the document from the standard input, output it to the standard output and store it into the cache. If there was an older version already in the cache, remove it.
Output information about one document in the cache to the standard output. The information is one line, with four space delimited fields: type, pathname of original, pathname of cached, and permanent flag (y or n).
Like --list, but for all documents.
Forget all cached documents that have been deleted.
dwww-cache maintains a database with information of the cached documents. The documents themselves are stored in separate files in the cache directory. When old documents are removed from the cache by a suitable crontab entry, they will still exist in the database. This operation removes all entries from the database where either the original or the converted file is now missing.
To stop the cache from growing too large, an entry in root's crontab should remove cached files that have not been accessed for a while. For example, the following commands remove all documents that have not been accessed for ten days:
find /var/cache/dwww -atime +10 | xargs rm -f
The idea is to first delete the old cached files and then clean up the database. The policy of cleaning the cache has been kept outside of dwww-cache to keep the program simple, and to allow maximum flexibility. The default dwww installation creates a /etc/cron.daily/dwww, which automatically cleans the cache each day.
The cache directory.
The database with information about all cached documents. This is a binary file, specially encoded for small size and high speed, and should not be touched by anyone but dwww-cache.