Administration Guide

The hostlist command

The hostlist command can be used to specify hostnames for parallel command execution by way of the dsh or sysctl command. The command writes hostnames to stdout based on various criteria:

• The contents of a dsh working collective file
• The contents of a POE hostname file
• All the nodes in the current system partition (-a option)
• All the nodes in the SP system (-aG option)
• Ranges of slots on particular frames
• A set of nodes to exclude
• A range of node numbers
• Explicitly listed hostnames

Note:

|The -a and -aG option defaults to using the |initial_hostname attribute from the SDR. If the HN_METHOD environment |variable is set to reliable (export HN_METHOD=reliable), the reliable_hostname |attribute will be used from the SDR. |

Before the names are written, there is an optional check of whether the nodes are responding.

The output from hostlist can be written to a file, which can then be used as a working collective file for dsh. Both dsh and sysctl can read hostnames from stdin, so the output of hostlist can be piped directly to dsh or sysctl.

Examples

To issue a command to the node in the first slot in each of the first 4 frames:

hostlist -s 1-4:1 | dsh -w - command

To run the program on the nodes on all slots for frame 1 and on slots 1-3 for frame 3, and also on host otherone:

hostlist -n 1-16,33-35 -w otherone > /tmp/wcoll
WCOLL=/tmp/wcoll dsh program

To determine all the nodes in the SP system on which one is authenticated, and to bypass the nodes that are not responding and "badnode", issue the command:

hostlist -av -e badnode | sysctl -c - -L whoami | dshbak -c

Note: The -L option on sysctl is necessary if the dshbak filter is used. It causes the output lines of sysctl to be formatted with the hostname preceding each line.

Output might look like this:

 HOSTS==============================================================
 host1             host2              host3             host4
 host5             host6              host8
 ===================================================================
 joe.@A.B.C
 
 HOSTS==============================================================
 host7
 ===================================================================
 unknown

If the -c option is not specified, output will not be collapsed:

HOST: host1
===========
joe.@A.B.C
 
HOST: host2
===========
joe.@A.B.C

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