CLUSH(1) ClusterShell User Manual CLUSH(1)
clush - execute shell commands on a cluster
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 ]
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 fea-
tures. clush currently makes use of the Ssh worker of ClusterShell that only requires ssh(1) (OpenSSH SSH client).
clush can be started non-interactively to run a shell command, or can be invoked as an interactive shell. To start a clush interactive ses-
sion, invoke the clush command without providing command.
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 syn-
tax 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
Please see some other great examples in the EXAMPLES section below.
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 con-
taining 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:
show current nodeset
set current nodeset
add nodes to current nodeset
remove nodes from current nodeset
execute COMMAND on the local system
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 des-
tination path is not specified, it will take the first file or dir basename directory as the local destination.
show clush version number and exit
-s GROUPSOURCE, --groupsource=GROUPSOURCE
optional groups.conf(5) group source to use
do not watch for possible input from stdin
Selecting target nodes:
nodes where to run the command
exclude nodes from the node list
run command on all nodes
-g GROUP, --group=GROUP
run command on a group of nodes
exclude nodes from this group
be quiet, print essential output only
be verbose, print informative messages
output more messages for debugging purpose
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 gath-
ering" of results by line mode, such as the next line is displayed as soon as possible (eg. when all nodes have sent the
-N disable labeling of command line
display gathered results in a dshbak-like way
-B like -b but including standard error
fold nodeset using node groups
-S return the largest of command return codes
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
copy local file or directory to remote nodes
copy file or directory from remote nodes
destination file or directory on the nodes (optional: use the first source directory path when not specified)
-p preserve modification times and modes
-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
-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.
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
clush: node[40-42]: exited with exit code 1
# clush -w node[3-5,62] uname -r
Run command uname -r in parallel on nodes: node3, node4, node5 and node62
# 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 gath-
# 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).
# 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.
# 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).
# 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.
System-wide clush configuration file.
This is the per-user clush configuration file.
File in which interactive clush command history is saved.
clubak(1), nodeset(1), readline(3), clush.conf(5), groups.conf(5).
Use the following URL to submit a bug report or feedback:
Stephane Thiell, CEA DAM <firstname.lastname@example.org>
1.6 2012-04-01 CLUSH(1)