htcacheclean - Clean up the disk cache

htcacheclean is used to keep the size of mod_cache_disk's storage within a given size limit, or limit on inodes in use. This tool can run either manually or in daemon mode. When running in daemon mode, it sleeps in the background and checks the cache directory at regular intervals for cached content to be removed. You can stop the daemon cleanly by sending it a TERM or INT signal. When run manually, a once off check of the cache directory is made for cached content to be removed. If one or more URLs are specified, each URL will be deleted from the cache, if present.

Synopsis

htcacheclean [ -D ] [ -v ] [ -t ] [ -r ] [ -n ] [ -Rround ] -ppath [-llimit| -Llimit]

htcacheclean [ -n ] [ -t ] [ -i ] [ -Ppidfile ] [ -Rround ] -dinterval -ppath [-llimit| -Llimit]

htcacheclean [ -v ] [ -Rround ] -ppath [ -a ] [ -A ]

htcacheclean [ -D ] [ -v ] [ -t ] [ -Rround ] -ppath url

Options

-dinterval

Daemonize and repeat cache cleaning every interval minutes. This option is mutually exclusive with the -D, -v and -r options. To shutdown the daemon cleanly, just send it a SIGTERM or SIGINT.

-D

Do a dry run and don't delete anything. This option is mutually exclusive with the -d option. When doing a dry run and deleting directories with -t, the inodes reported deleted in the stats cannot take into account the directories deleted, and will be marked as an estimate.

-v

Be verbose and print statistics. This option is mutually exclusive with the -d option.

-r

Clean thoroughly. This assumes that the Apache web server is not running (otherwise you may get garbage in the cache). This option is mutually exclusive with the -d option and implies the -t option.

-n

Be nice. This causes slower processing in favour of other processes. htcacheclean will sleep from time to time so that (a) the disk IO will be delayed and (b) the kernel can schedule other processes in the meantime.

-t

Delete all empty directories. By default only cache files are removed, however with some configurations the large number of directories created may require attention. If your configuration requires a very large number of directories, to the point that inode or file allocation table exhaustion may become an issue, use of this option is advised.

-ppath

Specify path as the root directory of the disk cache. This should be the same value as specified with the CacheRoot directive.

-Ppidfile

Specify pidfile as the name of the file to write the process ID to when daemonized.

-Rround

Specify round as the amount to round sizes up to, to compensate for disk block sizes. Set to the block size of the cache partition.

-llimit

Specify limit as the total disk cache size limit. The value is expressed in bytes by default (or attaching B to the number). Attach K for Kbytes or M for MBytes.

-Llimit

Specify limit as the total disk cache inode limit.

-i

Be intelligent and run only when there was a modification of the disk cache. This option is only possible together with the -d option.

-a

List the URLs currently stored in the cache. Variants of the same URL will be listed once for each variant.

-A

List the URLs currently stored in the cache, along with their attributes in the following order: url, header size, body size, status, entity version, date, expiry, request time, response time, body present, head request.

Deleting a specific URL

If htcacheclean is passed one or more URLs, each URL will be deleted from the cache. If multiple variants of an URL exists, all variants would be deleted.

When a reverse proxied URL is to be deleted, the effective URL is constructed from the Host header, the port, the path and the query. Note the '?' in the URL must always be specified explicitly, whether a query string is present or not. For example, an attempt to delete the path / from the server localhost, the URL to delete would be http://localhost:80/?.

Listing URLs in the Cache

By passing the -a or -A options to htcacheclean, the URLs within the cache will be listed as they are found, one URL per line. The -A option dumps the full cache entry after the URL, with fields in the following order:

url

The URL of the entry.

header size

The size of the header in bytes.

body size

The size of the body in bytes.

status

Status of the cached response.

entity version

The number of times this entry has been revalidated without being deleted.

date

Date of the response.

expiry

Expiry date of the response.

request time

Time of the start of the request.

response time

Time of the end of the request.

body present

If 0, no body is stored with this request, 1 otherwise.

head request

If 1, the entry contains a cached HEAD request with no body, 0 otherwise.

Exit Status

htcacheclean returns a zero status ("true") if all operations were successful, 1 otherwise. If an URL is specified, and the URL was cached and successfully removed, 0 is returned, 2 otherwise. If an error occurred during URL removal, 1 is returned.