NSCD.CONF(5) File Formats Manual NSCD.CONF(5)
nscd.conf - configuration file for Name Service Caching Daemon
/etc/nscd.conf configures the caches used by nscd(8) as well as some generic options. nscd(8) is able to use a configuration file at a
different location, when supplied with the -f or --config-file command line option.
The configuration file consists of a set of lines. Empty lines, and text after a '#' is ignored. All remaining lines denote the setting
of an option. White space before and after options, and between options and option arguments is ignored.
There are two kinds of options: General options influence nscd(8)'s general behaviour, while cache related options only affect the
specified cache. Options are set like this:
cache_option cache_name option
Specifies the name of the debug log-file that nscd(8) should use if debug-level is higher than 0. If this option is not set,
nscd(8) will write its debug output to stderr.
If level is higher than 0, nscd(8) will create some debug output. The higher the level, the more verbose the output.
This option sets the number of threads that nscd(8) should use by default. It can be overridden by calling nscd(8) with the -t or
--nthreads argument. If neither this configuration option nor the command line argument is given, nscd(8) uses 5 threads by default.
The minimum is 3. More threads means more simultaneous connections that nscd(8) can handle.
Specifies the maximum number of threads to be started.
By default, nscd(8) is run as user root. This option can be set to force nscd(8) to drop root privileges after startup. It cannot be
used when nscd(8) is called with the -S or --secure argument. Also note that some services require that nscd run as root, so using
this may break those lookup services.
Specifies the user who is allowed to request statistics.
bool must be one of yes or no. Enabling paranoia mode causes nscd(8) to restart itself periodically.
Sets the restart interval to time seconds if periodic restart is enabled by enabling paranoia mode. The default value is 3600.
All cache options take two arguments. The first one denotes the service or cache the option should affect. Currently service can be one of
passwd, group, or hosts.
enable-cache service bool
bool must be one of yes or no. Each cache is disabled by default and must be enabled explicitly by setting this options to yes.
positive-time-to-live service secs
This is the number of seconds after which a cached entry is removed from the cache. This defaults to 3600 seconds (i. e. one hour).
negative-time-to-live service secs
If an entry is not found by the Name Service, it is added to the cache and marked as "not existent". This option sets the number of
seconds after which such a not existent entry is removed from the cache. This defaults to 20 seconds for the password and host
caches and to 60 seconds for the group cache.
suggested-size service prime-number
This option sets the size of the hash that is used to store the cache entries. As this is a hash, it should be reasonably larger
than the maximum number of entries that is expected to be cached simultaneously and should be a prime number. It defaults to a size
of 211 entries.
check-files service bool
bool must be one of yes (default) or no. If file checking is enabled, nscd(8) periodically checks the modification time of
/etc/passwd, /etc/group, or /etc/hosts (for the passwd, group, and host cache respectively) and invalidates the cache if the file
has changed since the last check.
persistent service bool
bool must be one of yes (default) or no. Keep the content of the cache for service over nscd(8) restarts. Useful when paranoia mode
shared service bool
bool must be one of yes (default) or no. The memory mapping of the nscd(8) databases for service is shared with the clients so that
they can directly search in them instead of having to ask the daemon over the socket each time a lookup is performed.
Sets the number of times a cached record is reloaded before it is pruned from the cache. Each cache record has a timeout, when that
timeout expires, nscd(8) will either reload it (query the NSS service again if the data hasn't changed), or drop it.
max-db-size service number-of-bytes
Sets the maximum allowable size for the service.
auto-propagate service bool
When set to no for passwd or group service, then the .byname requests are not added to passwd.byuid or group.bygid cache. This may
help for tables containing multiple records for the same id.
# This is a comment.
enable-cache passwd yes
positive-time-to-live passwd 600
negative-time-to-live passwd 20
suggested-size passwd 211
check-files passwd yes
enable-cache group yes
positive-time-to-live group 3600
negative-time-to-live group 60
suggested-size group 211
check-files group yes
enable-cache hosts yes
positive-time-to-live hosts 3600
negative-time-to-live hosts 20
suggested-size hosts 211
check-files hosts yes
4.2 Berkeley Distribution 07 January 2001 NSCD.CONF(5)