Name

onnode — run commands on CTDB cluster nodes

Synopsis

onnode [OPTION...] {NODES} {COMMAND}

DESCRIPTION

onnode is a utility to run commands on a specific node of a CTDB cluster, or on all nodes.

NODES specifies which node(s) to run a command on. See section NODES SPECIFICATION for details.

COMMAND can be any shell command. The onnode utility uses ssh or rsh to connect to the remote nodes and run the command.

OPTIONS

-c

Execute COMMAND in the current working directory on the specified nodes.

-f FILENAME

Specify an alternative nodes FILENAME to use instead of the default. See the discussion of /usr/local/etc/ctdb/nodes in the FILES section for more details.

-i

Keep standard input open, allowing data to be piped to onnode. Normally onnode closes stdin to avoid surprises when scripting. Note that this option is ignored when using -p or if ONNODE_SSH is set to anything other than "ssh".

-n

Allow nodes to be specified by name rather than node numbers. These nodes don't need to be listed in the nodes file. You can avoid the nodes file entirely by combining this with -f /dev/null.

-p

Run COMMAND in parallel on the specified nodes. The default is to run COMMAND sequentially on each node.

-P

Push files to nodes. Names of files to push are specified rather than the usual command. Quoting is fragile/broken - filenames with whitespace in them are not supported.

-q

Do not print node addresses. Normally, onnode prints informational node addresses if more than one node is specified. This overrides -v.

-v

Print node addresses even if only one node is specified. Normally, onnode prints informational node addresses when more than one node is specified.

-h, --help

Show a short usage guide.

NODES SPECIFICATION

Nodes can be specified via numeric node numbers (from 0 to N-1) or mnemonics. Multiple nodes are specified using lists of nodes, separated by commas, and ranges of numeric node numbers, separated by dashes. If nodes are specified multiple times then the command will be executed multiple times on those nodes. The order of nodes is significant.

The following mnemonics are available:

all

All nodes.

any

A node where ctdbd is running. This semi-random but there is a bias towards choosing a low numbered node.

ok | healthy

All nodes that are not disconnected, banned, disabled or unhealthy.

con | connected

All nodes that are not disconnected.

EXAMPLES

The following command would show the process ID of ctdbd on all nodes 

      onnode all ctdb getpid

The following command would show the last 5 lines of log on each node, preceded by the node's hostname 

      onnode all "hostname; tail -5 /usr/local/var/log/log.ctdb"

The following command would restart the ctdb service on all nodes, in parallel. 

      onnode -p all service ctdb restart

The following command would run ./foo in the current working directory, in parallel, on nodes 0, 2, 3 and 4. 

      onnode -c -p 0,2-4 ./foo

FILES

/usr/local/etc/ctdb/nodes

Default file containing a list of each node's IP address or hostname.

As above, a file specified via the -f is given precedence. If a relative path is specified and no corresponding file exists relative to the current directory then the file is also searched for in the CTDB configuration directory.

Otherwise the default is /usr/local/etc/ctdb/nodes.

/usr/local/etc/ctdb/onnode.conf

If this file exists it is sourced by onnode. The main purpose is to allow the administrator to set ONNODE_SSH to something other than "ssh". In this case the -t option is ignored.

SEE ALSO

ctdb(7), http://ctdb.samba.org/