Section: File Formats (5)
Updated: 1999-10
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/etc/nscd.conf - name service cache daemon configuration file  


The file /etc/nscd.conf is read from nscd(8) at startup. Each line specifies either an attribute and a value, or an attribute, service, and a value. Fields are separated either by SPACE or TAB characters. A `#' (number sign) indicates the beginning of a comment; following characters, up to the end of the line, are not interpreted by nscd.

Valid services are passwd, group, or hosts.

logfile debug-file-name

Specifies name of the file to which debug info should be written.

debug-level value

Sets the desired debug level.

threads number

This is the number of threads that are started to wait for requests. At least five threads will always be created.

server-user user

If this option is set, nscd will run as this user and not as root. If a separate cache for every user is used (-S parameter), this option is ignored.

enable-cache service <yes|no>

Enables or disables the specified service cache.

positive-time-to-live service value

Sets the TTL (time-to-live) for positive entries (successful queries) in the specified cache for service. Value is in seconds. Larger values increase cache hit rates and reduce mean response times, but increase problems with cache coherence.

negative-time-to-live service value

Sets the TTL (time-to-live) for negative entries (unsuccessful queries) in the specified cache for service. Value is in seconds. Can result in significant performance improvements if there are several files owned by UIDs (user IDs) not in system databases (for example untarring the linux kernel sources as root); should be kept small to reduce cache coherency problems.

suggested-size service value

This is the internal hash table size, value should remain a prime number for optimum efficiency.

check-files service <yes|no>

Enables or disables checking the file belonging to the specified service for changes. The files are /etc/passwd, /etc/group, and /etc/hosts.

max-threads threads

Specifies the maximum number of threads to be started.

stat-user username

Specifies the user who is allowed to request statistics.

reload-count unlimited | number

Limit on the number of times a cached entry gets reloaded without being used before it gets removed. The default is 5.

paranoia <yes|no>

Enabling paranoia mode causes nscd to restart itself periodically.

restart-interval time

Sets the restart interval to time seconds if periodic restart is enabled by enabling paranoia mode.

persistent service <yes|no>

Keep the content of the cache for service over server restarts; useful when paranoia mode is set.

shared service <yes|no>

The memory mapping of the nscd 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 performend.

reload-count unlimited|<number>

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 will either reload it (query the NSS service again if the data hasn't changed), or drop it.

paranoia <yes|no>

Enables or disables restart of nscd every restart-interval .

restart-interval <time in seconds>

Is interval in which nscd is restarted if option paranoia is set. The default value is 3600.

  persistent service <yes|no>
Enables or disables persistent storage of data. Persistent caches are stored on the disk and therefore survive a nscd restart or e.g. machine reboot.

shared service <yes|no>

Enables or disables database saring among nscd clients (by being read-only mmapped in their address space, so the nscd client can directly do the lookup and only if an entry is not found there, ask nscd over socket to do the lookup).





nscd was written by Thorsten Kukuk and Ulrich Drepper.




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