NSCD(8) Maintenance Commands and Procedures NSCD(8)
NAME
nscd - name service cache daemon
SYNOPSIS
/usr/sbin/nscd [
-f configuration-file] [
-g] [
-e cachename, yes
| no] [
-i cachename]
DESCRIPTION
The
nscd daemon is a process that provides a cache for most name
service requests. The default
configuration-file /etc/nscd.conf determines the behavior of the cache daemon. See
nscd.conf(5).
nscd provides caching for the
passwd(5),
group(5),
hosts(5),
ipnodes(5),
exec_attr(5),
prof_attr(5),
user_attr(5),
ethers(5),
rpc(5),
protocols(5),
networks(5),
bootparams(5),
auth_attr(5),
services(5),
netmasks(5),
printers(5),
project(5) databases through
standard
libc interfaces, such as
gethostbyname(3NSL),
getipnodebyname(3SOCKET),
gethostbyaddr(3NSL), and others. Each cache
has a separate time-to-live for its data; modifying the local
database (
/etc/hosts,
/etc/resolv.conf, and so forth) causes that
cache to become invalidated upon the next call to
nscd. The shadow
file is specifically not cached.
getspnam(3C) calls remain uncached
as a result.
nscd also acts as its own administration tool. If an instance of
nscd is already running, commands are passed to the running version
transparently.
When running with per-user lookups enabled (see
nscd.conf(5)),
nscd forks one and only one child process (that is, a per-user
nscd) on
behalf of the user making the request. The per-user
nscd will use the
credentials of the user to open a per-user connection to the name
repository configured for the per-user style of lookups. The lookup
will be performed in the child process. The results are cached in the
process and are available only to the same user. The caches are
managed exactly the same as the main
nscd daemon manages its own
caches. Subsequent requests from the user will be handled by that
per-user
nscd until it terminates. The per-user
nscd uses a
configurable inactivity time-to-live (TTL) value and terminates
itself after the inactivity TTL expires.
The maximum number of per-user
nscds that can be created by the main
nscd is configurable (see
nscd.conf(5)). After the maximum number of
them are created, the main
nscd will use an LRU algorithm to
terminate less active child
nscds as needed.
The main
nscd daemon creates, monitors, and manages all the child
nscds. It creates a user's own
nscd upon receiving the user's first
per-user lookup. When the
nscd daemon is started, if per-user lookups
are enabled, it checks to ensure all conditions are met before
getting ready to create a per-user
nscd. When the daemon is stopped,
it terminates all the per-user
nscds under its control.
Per-user
nscds use the same configuration as the main
nscd. They read
and use the same default configuration file or the one specified with
the
-f command line option. Once the configuration is read, the per-
user
nscd will use it for its entire lifetime.
OPTIONS
Several of the options described below require a
cachename specification. Supported values for
cachename are:
passwd,
group,
hosts,
ipnodes,
exec_attr,
prof_attr,
user_attr,
ethers,
rpc,
protocols,
networks,
bootparams,
auth_attr,
services,
netmasks,
printers, and
project.
-f configuration-file Causes
nscd to read its configuration data from the specified
file.
-g Prints current configuration and statistics to standard output.
This is the only option executable by non-root users.
-e cachename, yes|
no Enables or disables the specified cache.
-i cachename Invalidate the specified cache.
EXAMPLES
Example 1: Stopping and restarting the nscd daemon.
example# svcadm disable system/name-service-cache
example# svcadm enable system/name-service-cache
FILES
/etc/nscd.conf Determines athe behavior of the cache daemon
SEE ALSO
svcs(1),
getspnam(3C),
gethostbyname(3NSL),
getipnodebyname(3SOCKET),
auth_attr(5),
bootparams(5),
ethers(5),
exec_attr(5),
group(5),
hosts(5),
netmasks(5),
networks(5),
nscd.conf(5),
nsswitch.conf(5),
passwd(5),
printers(5),
prof_attr(5),
project(5),
protocols(5),
rpc(5),
services(5),
user_attr(5),
attributes(7),
svcadm(8)NOTES
The output from the
-g option to
nscd is subject to change. Do not
rely upon it as a programming interface.
The
nscd service is managed by the service management facility,
smf(7), under the service identifier:
svc:/system/name-service-cache
Administrative actions on this service, such as enabling, disabling,
or requesting restart, can be performed using
svcadm(8). The
service's status can be queried using the
svcs(1) command.
March 6, 2017 NSCD(8)
