Linux Command Directory
This directory of Linux commands is from Linux in a Nutshell, 5th Edition.
Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.
nsupdate [options] [filename]
System administration command. Interactively submit dynamic DNS update requests to a nameserver. Use nsupdate to add or remove records from a zone without manually editing the zone file. Commands may be entered interactively or read from filename. An update message is built from multiple commands, some establishing prerequisites, some adding or deleting resource records. Messages are executed as a single transaction. A blank line or the send command will send the current message. Lines beginning with a semicolon are treated as comments. For additional information on dynamic DNS updates, see RFC 2136.
Print additional tracing information usable for debugging.
Read encrypted transaction signature key from keyfile. The key should be encrypted using the HMAC-MD5 algorithm. Keyfiles are generated by the dnssec-keygen command.
Use TCP instead of UDP to send update requests.
Generate transaction signature from specified keyname and secret.
Set default class to classname instead of the normal default IN.
Generate transaction signature from specified keyname and secret. This command overrides command-line options -k or -y.
Use local address and, if specified, port to send updates.
Specify prerequisites for updating a domain. Provide the criteria in one of the following forms:
Perform updates only if there are no preexisting records with the name domain-name.
nxrset domain-name [class] type
Perform updates only if there is no preexisting record of the specified type and class for domain-name. When no class is given, IN is assumed.
Perform updates only if there is a preexisting record with the name domain-name.
yxrset domain-name [class] type [data]
Perform updates only if there is a preexisting record of the specified type and class for domain-name. If data is given, the RDATA of the specified resource must match it exactly. When no class is given, IN is assumed.
Send the current message. Same as entering a blank line.
Update records on DNS server servername instead of the master server listed in the MNAME field of the appropriate zone's SOA record.
Print all commands in current message.
Update the records according to one of the following commands:
add domain-name [ttl] [class] type data
Add a resource record with the specified values.
delete domain-name [ttl] [class] [type [data] ]
Delete resource records for domain-name. The ttl field is always ignored, but if other fields are given, only delete records that match all criteria.
Apply updates to the specified zonename. If no zone command is given, nsupdate attempts to determine the correct zone based on other input.