--- name: "clush" section: "1" platform: "linux" package: "clustershell" version: "1.10.1-2" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/clush" --- # clush(1) execute shell commands on a cluster ## 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, by default, that only requires [**ssh**(1)](/ssh/1.md) (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 benefit from NodeSet basic arithmetic (like **@Agroup\\&@Bgroup**). See EXTENDED PATTERNS in [**nodeset**(1)](/nodeset/1.md) and also [**groups.conf**(5)](/groups.conf/5.md) 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)](/isatty/3.md)). 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 allow 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\> @\** set current nodeset - **clush\> +\** add nodes to current nodeset - **clush\> -\** 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 %%). **%hosts** will be replaced by the full target nodeset, in which case the command is executed only once. - **File copying mode ( --copy )** When **clush** is started with the **-c** or **--copy** option, it will attempt to copy specified *files* and/or *directories* to the provided cluster nodes. The **--dest** option can be used to specify a single path where all the file(s) should be copied to on the target nodes. In the absence of **--dest**, **clush** will attempt to copy each file or directory found in the command line to their same location on the target nodes. - **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 each *file* or *directory*'s parent directory as the local destination. ## OPTIONS - **--version** show **clush** version number and exit - **-s** *GROUPSOURCE,* **--groupsource=***GROUPSOURCE* optional [**groups.conf**(5)](/groups.conf/5.md) 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). - **--groupsconf=***FILE* use alternate config file for [**groups.conf**(5)](/groups.conf/5.md) - **--conf=***FILE* use alternate config file for [**clush.conf**(5)](/clush.conf/5.md) - **-O** *\,* **--option=***\* override any key=value [**clush.conf**(5)](/clush.conf/5.md) 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 behavior:** - **-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 (always **@groupname**) - **-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 (e.g. -bL), **clush** will enable a "live gathering" of results by line, so that the next line is displayed as soon as possible (e.g. when all nodes have sent the line) - **-N** disable labeling of command output - **-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 - **--axis=***RANGESET* for nD nodesets, fold the displayed nodeset (e.g. in gathered output headers) along provided axis only. Axes are indexed from 1 to n and can be specified here either using the rangeset syntax, e.g. '1', '1-2', '1,3', or by a single negative number meaning that the index is counted from the end. Because some nodesets may have several different dimensions, axis indices are silently truncated to fall in the allowed range. This is the per-invocation equivalent of the **fold\_axis** library default. - **-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 uses 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)](/clush.conf/5.md). - **-l** *USER,* **--user=***USER* execute remote command as user - **-o** *OPTIONS,* **--options=***OPTIONS* can be used to give ssh options, e.g. **-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 **\/\*.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). - **# clush -w dc\[1-2\]n\[1-2\] --axis=1 -b uname -r** Gather output and fold the displayed nodeset header along axis 1 only, e.g. show **dc\[1-2\]n1,dc\[1-2\]n2** rather than **dc\[1-2\]n\[1-2\]** in the header block. See also **fold\_axis** in the Library Defaults configuration to change it permanently. ### All nodes - **# clush -a uname -r** Run command *uname -r* on all cluster nodes, see [**groups.conf**(5)](/groups.conf/5.md) to set up 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)](/groups.conf/5.md) 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)](/nodeset/1.md) and also [**groups.conf**(5)](/groups.conf/5.md) 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, e.g. */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. - ***{sys.prefix}/etc/clustershell/clush.conf*** Configuration file when ClusterShell is installed in a Python virtual environment. - ***$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 (no longer read since version 1.9). - ***~/.clush\_history*** File in which interactive **clush** command history is saved. ## SEE ALSO [**clubak**(1)](/clubak/1.md), [**cluset**(1)](/cluset/1.md), [**nodeset**(1)](/nodeset/1.md), [**readline**(3)](/readline/3.md), [**clush.conf**(5)](/clush.conf/5.md), [**groups.conf**(5)](/groups.conf/5.md). *https://clustershell.readthedocs.io/* ## BUG REPORTS - **Use the following URL to submit a bug report or feedback:** *https://github.com/clustershell/clustershell/issues* ## AUTHOR Stephane Thiell ## COPYRIGHT GNU Lesser General Public License version 2.1 or later (LGPLv2.1+)