구차니의 잡동사니 모음

This is a feature that saves actual hard disk space when huge files that are mostly zeroes are stored.  ls will return the apparent file size, but du will show the apparent size of the file minus the size of the holes in the file (which is how much space the file actually uses on the disk). 

# systemctl stop libvirtd 

refresh_pattern ^ftp:           1440    20%     10080

refresh_pattern ^gopher:        1440    0%      1440

refresh_pattern -i (/cgi-bin/|\?) 0     0%      0

refresh_pattern .               0       20%     4320 

usage: refresh_pattern [-i] regex min percent max [options]

By default, regular expressions are CASE-SENSITIVE.  To make

them case-insensitive, use the -i option.

'Min' is the time (in minutes) an object without an explicit

expiry time should be considered fresh. The recommended

value is 0, any higher values may cause dynamic applications

to be erroneously cached unless the application designer

has taken the appropriate actions.

'Percent' is a percentage of the objects age (time since last

modification age) an object without explicit expiry time

will be considered fresh.

'Max' is an upper limit on how long objects without an explicit

expiry time will be considered fresh. The value is also used

to form Cache-Control: max-age header for a request sent from

Squid to origin/parent.

options: override-expire

override-lastmod

reload-into-ims

ignore-reload

ignore-no-store

ignore-private

max-stale=NN

refresh-ims

store-stale

#refresh_pattern .              0       20%     4320

refresh_pattern .               60      20%     4320