Provided by: clustershell_1.6-4_all 
NAME
clush - execute shell commands on a cluster
SYNOPSIS
clush -a | -g group | -w nodes [OPTIONS]
clush -a | -g group | -w nodes [OPTIONS] command
clush -a | -g group | -w nodes [OPTIONS] --copy file | dir [ file | dir ...] [ --dest
path ]
clush -a | -g group | -w nodes [OPTIONS] --rcopy file | dir [ file | dir ...] [ --dest
path ]
DESCRIPTION
clush is a program for executing commands in parallel on a cluster and for gathering their
results. clush executes commands interactively or can be used within shell scripts and
other applications. It is a partial front-end to the ClusterShell library that ensures a
light, unified and robust parallel command execution framework. Thus, it allows
traditional shell scripts to benefit from some of the library features. clush currently
makes use of the Ssh worker of ClusterShell that only requires ssh(1) (OpenSSH SSH
client).
INVOCATION
clush can be started non-interactively to run a shell command, or can be invoked as an
interactive shell. To start a clush interactive session, invoke the clush command without
providing command.
Non-interactive mode
When clush is started non-interactively, the command is executed on the specified
remote hosts in parallel. If option -b or --dshbak is specified, clush waits for
command completion and then displays gathered output results.
The -w option allows you to specify remote hosts by using ClusterShell NodeSet
syntax, including the node groups @group special syntax and the Extended Patterns
syntax to benefits from NodeSet basic arithmetics (like @Agroup\&@Bgroup). See
EXTENDED PATTERNS in nodeset(1) and also groups.conf(5) for more information.
Unless option --nostdin is specified, clush detects when its standard input is
connected to a terminal (as determined by isatty(3)). If actually connected to a
terminal, clush listens to standard input when commands are running, waiting for an
Enter key press. Doing so will display the status of current nodes. If standard
input is not connected to a terminal, and unless option --nostdin is specified,
clush binds the standard input of the remote commands to its own standard input,
allowing scripting methods like:
# echo foo | clush -w node[40-42] -b cat
---------------
node[40-42]
---------------
foo
Please see some other great examples in the EXAMPLES section below.
Interactive session
If a command is not specified, and its standard input is connected to a terminal,
clush runs interactively. In this mode, clush uses the GNU readline library to read
command lines. Readline provides commands for searching through the command history
for lines containing a specified string. For instance, type Control-R to search in
the history for the next entry matching the search string typed so far. clush also
recognizes special single-character prefixes that allows the user to see and modify
the current nodeset (the nodes where the commands are executed).
Single-character interactive commands are:
clush> ?
show current nodeset
clush> =<NODESET>
set current nodeset
clush> +<NODESET>
add nodes to current nodeset
clush> -<NODESET>
remove nodes from current nodeset
clush> !COMMAND
execute COMMAND on the local system
clush> =
toggle the output format (gathered or standard mode)
To leave an interactive session, type quit or Control-D.
File copying mode ( --copy )
When clush is started with the -c or --copy option, it will attempt to copy
specified file and/or dir to the provided target cluster nodes. If the --dest
option is specified, it will put the copied files there.
Reverse file copying mode ( --rcopy )
When clush is started with the --rcopy option, it will attempt to retrieve
specified file and/or dir from provided cluster nodes. If the --dest option is
specified, it must be a directory path where the files will be stored with their
hostname appended. If the destination path is not specified, it will take the first
file or dir basename directory as the local destination.
OPTIONS
--version
show clush version number and exit
-s GROUPSOURCE, --groupsource=GROUPSOURCE
optional groups.conf(5) group source to use
--nostdin
do not watch for possible input from stdin
Selecting target nodes:
-w NODES
nodes where to run the command
-x NODES
exclude nodes from the node list
-a, --all
run command on all nodes
-g GROUP, --group=GROUP
run command on a group of nodes
-X GROUP
exclude nodes from this group
Output behaviour:
-q, --quiet
be quiet, print essential output only
-v, --verbose
be verbose, print informative messages
-d, --debug
output more messages for debugging purpose
-G, --groupbase
do not display group source prefix
-L disable header block and order output by nodes; additionally, when used in
conjunction with -b/-B, it will enable "life gathering" of results by line
mode, such as the next line is displayed as soon as possible (eg. when all
nodes have sent the line)
-N disable labeling of command line
-b, --dshbak
display gathered results in a dshbak-like way
-B like -b but including standard error
-r, --regroup
fold nodeset using node groups
-S return the largest of command return codes
--color=WHENCOLOR
whether to use ANSI colors to surround node or nodeset prefix/header with
escape sequences to display them in color on the terminal. WHENCOLOR is
never, always or auto (which use color if standard output/error refer to a
terminal). Colors are set to [34m (blue foreground text) for stdout and [31m
(red foreground text) for stderr, and cannot be modified.
--diff show diff between common outputs (find the best reference output by focusing
on largest nodeset and also smaller command return code)
File copying:
-c, --copy
copy local file or directory to remote nodes
--rcopy
copy file or directory from remote nodes
--dest=DEST_PATH
destination file or directory on the nodes (optional: use the first source
directory path when not specified)
-p preserve modification times and modes
Ssh options:
-f FANOUT, --fanout=FANOUT
use a specified maximum fanout size (ie. do not execute more than FANOUT
commands at the same time, useful to limit resource usage)
-l USER, --user=USER
execute remote command as user
-o OPTIONS, --options=OPTIONS
can be used to give ssh options, eg. -o "-oPort=2022"
-t CONNECT_TIMEOUT, --connect_timeout=CONNECT_TIMEOUT
limit time to connect to a node
-u COMMAND_TIMEOUT, --command_timeout=COMMAND_TIMEOUT
limit time for command to run on the node
For a short explanation of these options, see -h, --help.
EXIT STATUS
By default, an exit status of zero indicates success of the clush command but gives no
information about the remote commands exit status. However, when the -S option is
specified, the exit status of clush is the largest value of the remote commands return
codes.
For failed remote commands whose exit status is non-zero, and unless the combination of
options -qS is specified, clush displays messages similar to:
clush: node[40-42]: exited with exit code 1
EXAMPLES
Basic
# clush -w node[3-5,62] uname -r
Run command uname -r in parallel on nodes: node3, node4, node5 and node62
Display features
# clush -w node[3-5,62] -b uname -r
Run command uname -r on nodes[3-5,62] and display gathered output results
(integrated dshbak-like).
# clush -w node[3-5,62] -bL uname -r
Line mode: run command uname -r on nodes[3-5,62] and display gathered output
results without default header block.
# ssh node32 find /etc/yum.repos.d -type f | clush -w node[40-42] -b xargs ls -l
Search some files on node32 in /etc/yum.repos.d and use clush to list the matching
ones on node[40-42], and use -b to display gathered results.
# clush -w node[3-5,62] --diff dmidecode -s bios-version
Run this Linux command to get BIOS version on nodes[3-5,62] and show version
differences (if any).
All nodes
# clush -a uname -r
Run command uname -r on all cluster nodes, see groups.conf(5) to setup all cluster
nodes (all: field).
# clush -a -x node[5,7] uname -r
Run command uname -r on all cluster nodes except on nodes node5 and node7.
# clush -a --diff cat /some/file
Run command cat /some/file on all cluster nodes and show differences (if any), line
by line, between common outputs.
Node groups
# clush -w @oss modprobe lustre
Run command modprobe lustre on nodes from node group named oss, see groups.conf(5)
to setup node groups (map: field).
# clush -g oss modprobe lustre
Same as previous example but using -g to avoid @ group prefix.
# clush -w @mds,@oss modprobe lustre
You may specify several node groups by separating them with commas (please see
EXTENDED PATTERNS in nodeset(1) and also groups.conf(5) for more information).
Copy files
# clush -w node[3-5,62] --copy /etc/motd
Copy local file /etc/motd to remote nodes node[3-5,62].
# clush -w node[3-5,62] --copy /etc/motd --dest /tmp/motd2
Copy local file /etc/motd to remote nodes node[3-5,62] at path /tmp/motd2.
# clush -w node[3-5,62] -c /usr/share/doc/clustershell
Recursively copy local directory /usr/share/doc/clustershell to the same path on
remote nodes node[3-5,62].
# clush -w node[3-5,62] --rcopy /etc/motd --dest /tmp
Copy /etc/motd from remote nodes node[3-5,62] to local /tmp directory, each file
having their remote hostname appended, eg. /tmp/motd.node3.
FILES
/etc/clustershell/clush.conf
System-wide clush configuration file.
~/.clush.conf
This is the per-user clush configuration file.
~/.clush_history
File in which interactive clush command history is saved.
SEE ALSO
clubak(1), nodeset(1), readline(3), clush.conf(5), groups.conf(5).
BUG REPORTS
Use the following URL to submit a bug report or feedback:
https://github.com/cea-hpc/clustershell/issues
AUTHOR
Stephane Thiell, CEA DAM <stephane.thiell@cea.fr>
COPYRIGHT
CeCILL-C V1