=head1 B<NAME>

B<xdsh> - Concurrently runs commands on multiple nodes.

=head1 B<SYNOPSIS>

B<xdsh> I<noderange> [B<-B> I<bypass>] [B<-C> I<context>] [B<-e>] [B<-E> I<environment_file>]  [B<-f> I<fanout>]
[B<-K>]  [B<-L>]  [B<-l>  I<userID>]   [B<-m>]   [B<-o>
I<node_options>] [B<-Q>] [B<-r> I<node_remote_shell>] [B<-s>] [B<-S> B<csh>|B<ksh>] [B<-t> I<timeout>]
[B<-T>] [B<-v>] [B<-X> I<env_list>] [B<-z>] I<command_list>

B<xdsh> [B<-i> I<image path>] I<command_list>

B<xdsh> [B<-h> | B<-V> | B<-q>]


=head1 B<DESCRIPTION>

The B<xdsh> command runs commands in parallel on remote  nodes.  The B<xdsh> command issues  a
remote  shell command for each target specified, and returns the output
from all targets,
formatted so that command results  from  all  nodes  can  be  managed.
The B<xdsh> command is an xCAT Distributed Shell Utility.

B<TARGET CONTEXT>:

The B<xdsh> command target context is the database  where  the  target  or
target  group is defined. A default context can be configured using the
B<-C> I<context> flag or the B<DSH_CONTEXT> environment variable. If neither are
specified, the default context is B<XCAT>.

A context is enabled for use with a DSH Utilities command by installing
a context extension file in the B</opt/xcat/xdsh/Context>  directory.  The
target  or target group context can be explicitly specified by qualify-
ing a target name with a context name, or implicitly defined by  speci-
fying  a  default  context  for  unqualified  target  names (See B<Target>
B<lists>).

B<TARGET> B<SPECIFICATION>:

A target is a node where a remote command will be executed.  Node
targets are specified inputting the I<node_list> or I<nodegroups>.

If  the local host is included as part of the targets, the I<command_list>
is executed directly on the local host and not through  the  configured
remote  shell,  unless  a  I<user_ID>  is specified for execution with the
local host (see B<Remote> B<user>).

Node targets can also be specified using node ranges  as  supported  by
xCAT.  If  the same target is specified more than once, the remote com-
mand will only be executed once on the specified target.

B<COMMAND> B<SPECIFICATION>:

The commands to execute on the remote  targets  are  specified  by  the
I<command_list>  B<xdsh>  parameter, or executing a local script using the B<-e>
flag.

The syntax for the I<command_list> B<xdsh> parameter is as follows:

I<command>[; I<command>]...


where I<command> is the command to run on the remote
target. Quotation marks are required to ensure that all commands in the
list are executed remotely, and that any special characters are interpreted
correctly on the remote target. A script file on the local host can be
executed on each of the remote targets by using the B<-e>
flag. If B<-e> is specified, I<command_list> is the
script name and arguments to the script. For example:

xdsh hostname -e I<script_filename> [I<arguments>]...

The I<script_filename> file is copied to a random  filename  in  the  B</tmp>
directory on each remote target and then executed on the targets.

The B<xdsh> command does not work with any interactive commands, including
those that read from standard input.

B<REMOTE> B<SHELL> B<COMMAND>:

The  B<xdsh>  command  uses a configurable remote shell command to execute
remote commands on the remote targets. Support is  explicitly  provided
for  AIX  Remote  Shell and OpenSSH, but any secure remote command that
conforms to the IETF (Internet Engineering Task  Force)  Secure  Remote
Command Protocol can be used.

The remote shell is determined as follows, in order of precedence:

1. The B<-r> flag.

2. The B<DSH_NODE_RSH> environment variable.

3. The default node remote shell as defined by the target I<context>.

4. The B</usr/bin/ssh> command.

The  remote shell options are determined as follows, in order of prece-
dence:

1. The B<-o> flag.

2. The B<DSH_NODE_OPTS> environment variable.

B<REMOTE> B<SHELL> B<ENVIRONMENT>:

The shell environment used on the remote target defaults to  the  shell
defined for the I<user_ID> on the remote target.  The command
syntax that B<xdsh> uses to form the remote commands can be specified using the  B<-S>
flag. If B<-S> is not specified, the syntax defaults to B<sh> syntax.

When  commands  are  executed  on  the  remote target, the path used is
determined by the B<DSH_PATH> environment variable defined in the shell of
the  current  user. If B<DSH_PATH> is not set, the path used is the remote
shell default path. For example, to set the local path for  the  remote
targets, use:

DSH_PATH=$PATH

The  B<-E> flag exports a local environment definition file to each remote
target. Environment variables specified in this file are defined in the
remote shell environment before the I<command_list> is executed.

B<COMMAND> B<EXECUTION>:

The  maximum  number  of concurrent remote shell command processes (the
fanout) can be specified with the B<-f> flag or with the B<DSH_FANOUT>
environment variable. The fanout is only restricted by the number of remote
shell commands that can be run in parallel. You can experiment with the
B<DSH_FANOUT>  value on your management server to see if higher values are
appropriate.

A timeout value for remote command execution can be specified with  the
B<-t>  flag  or  with  the B<DSH_TIMEOUT> environment variable. If any remote
target does not provide output to either standard  output  or  standard
error  within  the  timeout  value,  B<xdsh> displays an error message and
exits.

If streaming mode is specified with the B<-s> flag, output is returned  as
it  becomes available from each target, instead of waiting for the
I<command_list> to complete on all targets before returning output. This  can
improve performance but causes the output to be unsorted.

The  B<-z> flag displays the exit code from the last command issued on the
remote node in I<command_list>. Note that OpenSSH behaves differently;  it
returns  the  exit status of the last remote command issued as its exit
status. This affects the behavior of B<xdsh> and may require using the  B<-c>
flag.  If  the  command  issued  on the remote node is run in the
background, the exit status is not displayed.

The B<-m> flag monitors execution of the B<xdsh> command by  printing  status
messages to standard output. Each status message is preceded by B<dsh>.

The B<-T> flag provides diagnostic trace information for the execution of
the B<xdsh> command. Default settings and the actual remote shell commands
executed on the remote targets are displayed.

No error detection  or recovery mechanism is provided for remote
targets. The B<xdsh> command output to standard error and standard output can
be analyzed to determine the appropriate course of action.  In interac-
tive mode, if a command cannot be executed  on  a  remote  target  (for
example,  a  remote shell command resulting in a non-zero return code),
subsequent commands are not sent to this node on this invocation of the
B<xdsh> command unless the B<-c> flag is specified.

B<COMMAND> B<OUTPUT>:

The  B<xdsh>  command  waits  until complete output is available from each
remote shell process and then displays that  output  before  initiating
new  remote shell processes. This default behavior is overridden by the
B<-s> flag.

The B<xdsh> command output consists of standard error and standard  output
from the remote commands. The B<xdsh> standard output is the standard
output from the remote shell command. The B<xdsh> standard error is the
standard  error  from the remote shell command.  Each line is prefixed with
the host name of the node that produced the output. The  host  name  is
followed  by  the  B<:>  character and a command output line. A filter for
displaying identical outputs grouped by node  is  provided  separately.
See the B<xdshbak> command for more information.

A  command  can  be run silently using the B<-Q> flag; no output from each
target's standard output or standard error is displayed.

B<SIGNALS>:

Signal 2 (INT), Signal 3 (QUIT), and Signal 15 (TERM) are propagated to
the commands executing on the remote targets.

Signal  19  (CONT),  Signal  17 (STOP), and Signal 18 (TSTP) default to
B<xdsh>; the B<xdsh> command responds normally to these signals, but the
signals  do  not have an effect on remotely executing commands. Other
signals are caught by B<xdsh> and have their default effects on the B<xdsh>
command; all current child processes, through propagation to remotely
running commands, are terminated (SIGTERM).

=head1 B<OPTIONS>

=over 5

=item B<-C>|B<--context> I<context>

The default context to use when resolving target names. The
I<context> value must correspond to a valid context  extension
module  in  the B</opt/xcat/xdsh/Context> directory. For
example, the B</opt/xcat/xdsh/Context/DSH.pm> file is  the  module
for the B<DSH> context.

=item B<-e>|B<--execute>

Indicates  that I<command_list> specifies a local script
filename and arguments to be executed on  the  remote  targets.
The  script  file  is copied to the remote targets and then
remotely   executed   with   the   given   arguments.   The
B<DSH_NODE_RCP>  environment variables specify the remote copy
command to use to copy the script file to node targets.

=item B<-E>|B<--environment> I<environment_file>

Specifies that the  I<environment_file>  contains  environment
variable definitions to export to the target before
executing the  I<command_list>.  The  B<DSH_NODE_RCP>  and  environment
variables  specify the remote copy command to use to export
the file to node targets.

=item B<-f>|B<--fanout> I<fanout_value>

Specifies a fanout value for the maximum number of  concur-
rently  executing  remote shell processes. Serial execution
can be specified by indicating a fanout value of B<1>.  If  B<-f>
is not specified, a default fanout value of B<64> is used.

=item B<-h>|B<--help>

Displays usage information.

=item B<-K>|B<--ssh-setup>

Set  up  the  SSH  keys  for the specified node list.
Currently, this must be run on the management node (not  on  a
remote  client), because it forces itself into bypass mode.

=item B<-l>|B<--user> I<user_ID>

Specifies a remote user name to use for remote command exe-
cution.

=item B<-L>|B<--no-locale>

Specifies to not export the locale definitions of the local
host to the remote targets. Local host  locale  definitions
are exported by default to each remote target.

=item B<-m>|B<--monitor>

Monitors  remote  shell execution by displaying status
messages during execution on each target.

=item B<-o>|B<--node-options> I<node_options>

Specifies options to pass to the remote shell  command  for
node  targets.  The options must be specified within double
quotation marks ("") to distinguish them from B<xdsh> options.

=item B<-q>|B<--show-config>

Displays the current environment settings for all DSH
Utilities commands. This includes the values of all environment
variables  and  settings  for  all  currently installed and
valid contexts. Each setting is prefixed with  I<context>:  to
identify the source context of the setting.

=item B<-Q>|B<--silent>

Specifies silent mode. No target output is written to stan-
dard output or  standard  error.  Monitoring  messages  are
written to standard output.

=item B<-r>|B<--node-rsh> I<node_remote_shell>


Specifies  the  full  path of the remote shell command used
for remote command execution on node targets.


=item B<-i>|B<--rootimg> I<install image>


Specifies  the  full  path to the install image on the local node. 
xdsh will chroot to this path and run the xdsh command against the
install image.  No other xdsh flags, environment variables apply with 
this input.  A noderange is not accepted. Only runs on the local host, 
normally the Management Node. 


=item B<-s>|B<--stream>

Specifies that output is returned as it  becomes  available
from  each  target, instead of waiting for the I<command_list>
to be completed on a target before returning output.

=item B<-S>|B<--syntax> B<csh>|B<ksh>

Specifies the shell syntax to be used on the remote target.
If not specified, the B<ksh> syntax is used.

=item B<-t>|B<--timeout> I<timeout>

Specifies the time, in seconds, to wait for output from any
currently executing remote targets. If no output is
available  from  any  target in the specified I<timeout>, B<xdsh>
displays an error and terminates execution for the remote
targets  that  failed to respond. If I<timeout> is not specified,
B<xdsh> waits indefinitely to continue processing output  from
all  remote  targets.  When specified with the B<-i> flag, the
user is prompted for an additional timeout interval to wait
for output.

=item B<-T>|B<--trace>

Enables trace mode. The B<xdsh> command prints diagnostic
messages to standard output during execution to each target.

=item B<-v>|B<--verify>

Verifies each target before executing any  remote  commands
on  the target. If a target is not responding, execution of
remote commands for the target is canceled. When  specified
with the B<-i> flag, the user is prompted to retry the
verification request.

=item B<-V>|B<--version>

Displays the B<xdsh> command version information.

=item B<-X> I<env_list>

Ignore B<xdsh> environment variables. This option can take  an
argument  which  is  a  comma separated list of environment
variable names that should B<NOT> be ignored. If there  is  no
argument  to  this  option,  or  the  argument  is an empty
string, all B<xdsh> environment variables will be ignored.
This option is useful when running B<xdsh> from within other
scripts when you don't want the user's environment affecting
the behavior of xdsh.

=item B<-z>|B<--exit-status>

Displays the exit status for  the  last  remotely  executed
non-asynchronous  command  on  each  target. If the command
issued on the remote node is run  in  the  background,  the
exit status is not displayed.

Exit  values  for  each remote shell execution are displayed in
messages from the B<xdsh> command, if the remote  shell  exit  values  are
non-zero.  A non-zero return code from a remote shell indicates that
an error was encountered in the remote shell. This  return  code  is
unrelated  to  the  exit  code  of the remotely issued command. If a
remote shell encounters an error, execution of the remote command on
that target is bypassed.

The  B<xdsh>  command  exit  code  is B<0> if the command executed without
errors and all remote shell commands finished with exit codes of  B<0>.
If  internal  B<xdsh>  errors occur or the remote shell commands do not
complete successfully, the B<xdsh> command exit value is  greater  than
B<0>.  The exit value is increased by B<1> for each successive instance of
an unsuccessful remote command execution.  If  the  remotely  issued
command  is  run  in  the  background, the exit code of the remotely
issued command is B<0>.

=back


=head1 B<Environment> B<Variables>

=over 4

=item B<DSH_CONTEXT>

Specifies the default context to use  when  resolving
targets. This variable is overridden by the B<-C> flag.

=item B<DSH_ENVIRONMENT>

Specifies a file that contains environment variable
definitions to export to the target before executing  the  remote
command. This variable is overridden by the B<-E> flag.

=item B<DSH_FANOUT>

Specifies  the fanout value. This variable is overridden by
the B<-f> flag.

=item B<DSH_NODE_OPTS>

Specifies the options to use for the remote  shell  command
with  node targets only. This variable is overridden by the
B<-o> flag.

=item B<DSH_NODE_RCP>

Specifies the full path of the remote copy command  to  use
to  copy  local scripts and local environment configuration
files to node targets.

=item B<DSH_NODE_RSH>

Specifies the full path of the  remote  shell  to  use  for
remote  command execution on node targets. This variable is
overridden by the B<-r> flag.

=item B<DSH_NODEGROUP_PATH>

Specifies a colon-separated list of directories  that
contain node group files for the B<DSH> context. When the B<-a> flag
is specified in the B<DSH> context,  a  list  of  unique  node
names is collected from all node group files in the path.

=item B<DSH_PATH>

Sets the command path to use on the targets. If B<DSH_PATH> is
not set, the default path defined in  the  profile  of  the
remote I<user_ID> is used.

=item B<DSH_SYNTAX>

Specifies the shell syntax to use on remote targets; B<ksh> or
B<csh>. If not specified, the  B<ksh>  syntax  is  assumed.  This
variable is overridden by the B<-S> flag.

=item B<DSH_TIMEOUT>

Specifies  the  time,  in  seconds, to wait for output from
each remote target. This variable is overridden by  the  B<-t>
flag.

=back


=head1 B<Security>

The  B<xdsh>  command  has no security configuration requirements.  All
remote command security requirements  -  configuration,
authentication,  and authorization - are imposed by the underlying remote
command configured for B<xdsh>. The command  assumes  that  authentication
and  authorization  is  configured  between  the  local host and the
remote targets. Interactive password prompting is not supported;  an
error  is displayed and execution is bypassed for a remote target if
password prompting occurs, or if either authorization or
authentication  to  the  remote  target fails. Security configurations as they
pertain to the remote environment and remote shell command are
userdefined.


=head1 B<Examples>

=over 3

=item *

To run the B<ps> command on node targets B<node1> and B<node2>, enter:

B<xdsh> I<node1,node2 ps>

=item *

To execute the commands contained in B<myfile> in the B<XCAT>
context on several node targets, with a fanout of B<1>, enter:

B<xdsh> I<node1,node2 -C XCAT -f 1 -e myfile>


=item *

To run the ps command on node1 and ignore all the dsh
environment variable except the DSH_NODE_OPTS, enter:

B<xdsh> I<node1 -X `DSH_NODE_OPTS' ps>


=item *

To run on Linux, the xdsh command "rpm -qa | grep xCAT" 
on the service node fedora9 diskless image, enter:

B<xdsh> I<-i /install/netboot/fedora9/x86_64/service/rootimg "rpm -qa | grep xCAT">


=item *

To run on AIX, the xdsh command "lslpp -l | grep bos"  
on the NIM 611dskls spot, enter:

B<xdsh> I<-i /install/nim/spot/611dskls "/usr/bin/lslpp -l | grep bos">

=back

=head1 B<Files>

B</opt/xcat/xdsh/Context/>

Location of the contexts available to use with  DSH  Utilities.

=head1 B<SEE ALSO>

L<xdshbak(1)|xdshbak.1>, L<noderange(3)|noderange.3>
