SYNOPSIS

dwww-cache --lookup type location
dwww-cache --store type location
dwww-cache --list type location
dwww-cache --list-all
dwww-cache --clean

DESCRIPTION

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:

--lookup

If the document is in the cache, output it to the standard output. Otherwise, output nothing and return a non-zero status.

--store

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.

--list

Output information about one document in the cache to the standard output. The information is one line, with five space delimited fields: type, pathname of original file, pathname of cached file, size (actually the last two bytes of size) of the cached file, and cache entry validity indicator (which can be either "valid" or "outdated").

--list-all

Like --list, but for all documents.

--clean

Forget all cached documents that are already outdated.

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. The --clean operation removes all entries from the database where either the original or the converted file is missing or where the converted file is outdated.

To stop the cache from growing too large, there should be an entry for dwww-refresh-cache(8) in system crontab to remove cached files that have not been accessed for a while. The dwww-refresh-cache(8) program internally uses commands similar to

find /var/cache/dwww -atime +$DWWW_KEEPDAYS | xargs rm -f
dwww-cache --clean

to remove all documents that have not been accessed for a number of days specified in the $DWWW_KEEPDAYS configuration variable.

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.

FILES

/var/cache/dwww/db

The cache directory.

/var/cache/dwww/db/.cache_db

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.

AUTHOR

Lars Wirzenius <[email protected]>. Modified by Robert Luberda <[email protected]>.
See dwww(7) for copyrights and stuff.