=========
 clush
=========

-----------------------------------
execute shell commands on a cluster
-----------------------------------

:Author: Stephane Thiell <sthiell@stanford.edu>
:Date:   2023-02-09
:Copyright: GNU Lesser General Public License version 2.1 or later (LGPLv2.1+)
:Version: 1.9.1
:Manual section: 1
:Manual group: ClusterShell User Manual


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, by default, 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 arithmetic
  (like ``@Agroup\&@Bgroup``). See EXTENDED PATTERNS in ``nodeset``\(1) and
  also ``groups.conf``\(5) for more information.

  Unless the option ``--nostdin`` (or ``-n``) 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 the 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.

Local execution ( ``--worker=exec`` or ``-R exec`` )
  Instead of running provided command on remote nodes, ``clush`` can use the
  dedicated *exec* worker to launch the command *locally*, for each node.
  Some parameters could be used in the command line to make a different
  command for each node. ``%h`` or ``%host`` will be replaced by node name and
  ``%n`` or ``%rank`` by the remote rank [0-N] (to get a literal % use %%)

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
-n, --nostdin         do not watch for possible input from stdin; this should be used when ``clush`` is run in the background (or in scripts).
--sudo                enable sudo password prompt: a prompt will ask for your sudo password and sudo will be used to run your commands on the target nodes. The password must be the same on all target nodes. The actual sudo command used by ``clush`` can be changed in ``clush.conf``\(5) or in command line using ``-O sudo_command="..."``. The configured ``sudo_command`` must be able to read a password on stdin followed by a new line (which is what ``sudo -S`` does).
--groupsconf=FILE     use alternate config file for groups.conf(5)
--conf=FILE           use alternate config file for clush.conf(5)
-O <KEY=VALUE>, --option=<KEY=VALUE>
                      override any key=value ``clush.conf``\(5) options (repeat as needed)

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
  --hostfile=FILE, --machinefile=FILE
                      path to a file containing a list of single hosts, node sets or node groups, separated by spaces and lines (may be specified multiple times, one per file)
  --topology=FILE     topology configuration file to use for tree mode
  --pick=N            pick N node(s) at random in nodeset

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; if -b/-B is not specified, ``clush`` will wait for all commands to finish and then display aggregated output of commands with same return codes, ordered by node name; alternatively, when used in conjunction with -b/-B (eg. -bL), ``clush`` will enable a "life gathering" of results by line, 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
  -P, --progress      show progress during command execution; if writing is performed to standard input, the live progress indicator will display the global bandwidth of data written to the target nodes
  -b, --dshbak        display gathered results in a dshbak-like way (note: it will only try to aggregate the output of commands with same return codes)
  -B                  like -b but including standard error
  -r, --regroup       fold nodeset using node groups
  -S, --maxrc         return the largest of command return codes
  --color=WHENCOLOR   ``clush`` can use NO_COLOR, CLICOLOR and CLICOLOR_FORCE environment variables. NO_COLOR takes precedence over CLICOLOR_FORCE which takes precedence over CLICOLOR.  When ``--color`` option is used these environment variables are not taken into account. ``--color`` tells 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)
  --outdir=OUTDIR     output directory for stdout files (OPTIONAL)
  --errdir=ERRDIR     output directory for stderr files (OPTIONAL)

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

Connection options:
  -f FANOUT, --fanout=FANOUT
                      do not execute more than FANOUT commands at the same time, useful to limit resource usage. In tree mode, the same *fanout* value is used on the head node and on each gateway (the *fanout* value is propagated). That is, if the *fanout* is **16**, each gateway will initiate up to **16** connections to their target nodes at the same time. Default *fanout* value is defined in ``clush.conf``\(5).
  -l USER, --user=USER
                      execute remote command as user
  -o OPTIONS, --options=OPTIONS
                      can be used to give ssh options, eg. ``-o "-p 2022 -i ~/.ssh/myidrsa"``; these options are added first to ssh and override default ones
  -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
  -m MODE, --mode=MODE
                      run mode; define MODEs in ``<confdir>/*.conf``
  -R WORKER, --worker=WORKER
                      worker name to use for connection (``exec``, ``ssh``, ``rsh``, ``pdsh``, or the name of a Python worker module), default is ``ssh``
  --remote=REMOTE     whether to enable remote execution: in tree mode, 'yes' forces connections to the leaf nodes for execution, 'no' establishes connections up to the leaf parent nodes for execution (default is 'yes') 

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
===========

Remote parallel execution
-------------------------

:# clush -w node[3-5,62] uname -r:
    Run command `uname -r` in parallel on nodes: node3, node4, node5 and node62

Local parallel execution
------------------------

:# clush -w node[1-3] --worker=exec ping -c1 %host:
    Run locally, in parallel, a ping command for nodes: node1, node2 and node3.
    You may also use ``-R exec`` as the shorter and pdsh compatible option.

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
=====

*$CLUSTERSHELL_CFGDIR/clush.conf*
  Global clush configuration file. If $CLUSTERSHELL_CFGDIR is not defined,
  */etc/clustershell/clush.conf* is used instead.

*$XDG_CONFIG_HOME/clustershell/clush.conf*
  User configuration file for clush. If $XDG_CONFIG_HOME is not defined,
  *$HOME/.config/clustershell/clush.conf* is used instead.

*$HOME/.local/etc/clustershell/clush.conf*
  Local user configuration file for clush (default installation for pip --user)

*~/.clush.conf*
  Deprecated per-user clush configuration file.

*~/.clush_history*
  File in which interactive ``clush`` command history is saved.

SEE ALSO
========

``clubak``\(1), ``cluset``\(1), ``nodeset``\(1), ``readline``\(3), ``clush.conf``\(5), ``groups.conf``\(5).

http://clustershell.readthedocs.org/

BUG REPORTS
===========

Use the following URL to submit a bug report or feedback:
  https://github.com/cea-hpc/clustershell/issues

