The
nscd
utility
is the system caching daemon.
It can cache almost all types of data and is basically intended to be used
with the
nsswitch
subsystem.
The cache is actually per-user.
This means that each user can work only with the
cached data that were cached by themselves, and cannot poison the
cache of other users.
The
nscd
utility supports two types of caching:
|
| Type
|
Description
|
| Common caching
|
| |
Each cached element is the key+value pair.
This type of caching supports policies which are applied when maximum
number of cached elements is exceeded.
Three policies are available:
FIFO
(first in - first out),
LRU
(least recently used) and
LFU
(least frequently used).
This type of caching is used with the
getXXXbyname()
family of functions.
|
| Multipart caching
|
| |
Each cached element is the part of the elements sequence.
This type of caching is intended to be used with the
getXXXent()
family of functions.
|
|
The
nscd
utility is able not only to cache elements, but to perform the actual nsswitch
lookups by itself.
To enable this feature, use the
perform-actual-lookups
parameter in
nscd.conf(5).
The
nscd
utility recognizes the following runtime options:
| -n
|
| |
Do not daemonize;
nscd
will not fork or disconnect itself from the terminal.
|
| -s
|
| |
Single-threaded mode.
Forces using only one thread for all processing purposes (it overrides
the
threads
parameter in the
nscd.conf(5)
file).
|
| -t
|
| |
Trace mode.
All trace messages will be written to stdout.
This mode is usually used with
-n
and
-s
flags are used for debugging purposes.
|
| -i cachename
|
| |
Invalidates personal cache.
When specified,
nscd
acts as the administration tool.
It asks the already running
nscd
to invalidate the specified part of the cache of the
calling user.
For example, sometimes you may want to invalidate your
"hosts"
cache.
You can specify
"all"
as the
cachename
to invalidate your personal cache as a whole.
You cannot use this option for the
cachename
for which the
perform-actual-lookups
option is enabled.
|
| -I cachename
|
| |
Invalidates the cache for every user.
When specified,
nscd
acts as the administration tool.
It asks the already
running
nscd
to invalidate the specified part of the cache for
every user.
You can specify
"all"
as the
cachename
to invalidate the whole cache.
Only the root can use this option.
|
|
