Command fanout is based on the open source tool Parallel
Distributed Shell (pdsh). pdsh enables the administrator to execute shell commands in parallel
across a set of systems. It can use remsh or ssh as the network transports. The csshsetup tool is provided to simplify the distribution of ssh keys. The companion utility Parallel Distributed Copy (pdcp) enables file and directory copies to be performed
in parallel to a set of remote systems. The dshbak filter allows the output from multiple systems to be formatted and
consolidated for better on-screen presentation.
The cexec, ccp, ckill, cps, and cuptime tools
are wrappers around the pdsh and pdcp commands optimized for use in a Serviceguard cluster. They default
to executing commands cluster-wide. These wrappers do the following:
cexec - Like pdsh but with additional reporting and retry features
ccp - Copies files cluster-wide
ckill - Kills the named process
cluster-wide or on the specified systems
cps - Issues a ps command cluster-wide or on the specified systems
cuptime - Runs the uptime command cluster-wide
These commands can also be used outside a cluster, but like pdsh and pdcp, the user must specify
a list of target hosts. The cexec command operates
like pdsh and adds reporting capabilities. Saved
reports can be used to reissue previous commands and target only those
systems where the command originally failed, originally succeeded,
or both. Command fanout is more fully described in Chapter 4: “Command Fanout”.