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Updated: Wednesday, July 27, 2022

cssh (1)


cssh - Cluster administration tool


cssh [-a '<command>'] [-K <seconds>] [-q] [-c '<filename>'] [-C
'<filename>'] [--debug [[...] || <INTEGER>]] [-d] [-e
'<[user@]<host>[:port]>'] [-f '<font>'] [-h] [-L '[tag]'] [-H] [-o
'<STRING>'] [-p <port>] [-Q] [-s] [-r '<filename>'] [-t '<STRING>']
[-g] [-T '<title>'] [-u] [-?] [-A] [-l '<username>'] [-v]


User Contributed Perl Documentation                                    CSSH(1)

       cssh - Cluster administration tool

       cssh [-a '<command>'] [-K <seconds>] [-q] [-c '<filename>'] [-C
       '<filename>'] [--debug [[...] || <INTEGER>]] [-d] [-e
       '<[user@]<host>[:port]>'] [-f '<font>'] [-h] [-L '[tag]'] [-H] [-o
       '<STRING>'] [-p <port>] [-Q] [-s] [-r '<filename>'] [-t '<STRING>']
       [-g] [-T '<title>'] [-u] [-?] [-A] [-l '<username>'] [-v]

       The command opens an administration console and an xterm to all
       specified hosts.  Any text typed into the administration console is
       replicated to all windows.  All windows may also be typed into

       This tool is intended for (but not limited to) cluster administration
       where the same configuration or commands must be run on each node
       within the cluster.  Performing these commands all at once via this
       tool ensures all nodes are kept in sync.

       Connections are opened using ssh which must be correctly installed and

       Extra caution should be taken when editing files as lines may not
       necessarily be in the same order;  assuming line 5 is the same across
       all servers and modifying that is dangerous.  It's better to search for
       the specific line to be changed and double-check all terminals are as
       expected before changes are committed.

   Further Notes
       Please also see "KNOWN BUGS".

       o   The dotted line on any sub-menu is a tear-off, i.e. click on it and
           the sub-menu is turned into its own window.

       o   Unchecking a hostname on the Hosts sub-menu will unplug the host
           from the cluster control window, so any text typed into the console
           is not sent to that host.  Re-selecting it will plug it back in.

       o   If your window manager menu bars are obscured by terminal windows
           see the "screen_reserve_XXXXX" options in the
           $HOME/.clusterssh/config file (see "FILES").

       o   If the terminals overlap too much see the "terminal_reserve_XXXXX"
           options in the $HOME/.clusterssh/config file (see "FILES").

       o   When using ClusterSSH on a large number of systems to connect to a
           single system using an SSH utility (e.g. you issue a command to to
           copy a file using scp from the remote computers to a single host)
           and when these connections require authentication (i.e. you are
           going to authenticate with a password), the sshd daemon at that
           location may refuse connections after the number "MaxStartups"
           limit in sshd_config is exceeded.  (If this value is not set, it
           defaults to 10).  This is expected behavior; sshd uses this
           mechanism to prevent DoS attacks from unauthenticated sources.
           Please tune sshd_config and reload the SSH daemon, or consider
           using the ~/.ssh/authorized_keys mechanism for authentication if
           you encounter this problem.

       o   If client windows fail to open, try running:

           "cssh -e {single host name}"

           This will test the mechanisms used to open windows to hosts.  This
           could be due to either the "-xrm" terminal option which enables
           "AllowSendEvents" (some terminals do not require this option, other
           terminals have another method for enabling it - see your terminal
           documentation) or the configuration of "ssh".

       Some of these options may also be defined within the configuration
       file.  Default options are shown as appropriate.

       --action '<command>', -a '<command>'
           Run the command in each session, e.g. "-a 'vi /etc/hosts'" to drop
           straight into a vi session.

       --autoclose <seconds>, -K <seconds>
           Number of seconds to wait before closing finished terminal windows.

       --autoquit, -q
           Toggle automatically quiting after the last client window has
           closed (overriding the config file).

       --cluster-file '<filename>', -c '<filename>'
           Use supplied file as additional cluster file (see also "FILES").

       --config-file '<filename>', -C '<filename>'
           Use supplied file as additional configuration file (see also

       --debug [[...] || <INTEGER>]
           Enable debugging.  Either a level can be provided or the option can
           be repeated multiple times.  Maximum level is 9.

       --dump-config, -d
           Dump the current configuration in the same format used by the
           $HOME/.clusterssh/config file.

       --evaluate '<[user@]<host>[:port]>', -e '<[user@]<host>[:port]>'
           Display and evaluate the terminal and connection arguments to
           display any potential errors.  The <hostname> is required to aid
           the evaluation.

       --font '<font>', -f '<font>'
           Specify the font to use in the terminal windows. Use standard X
           font notation such as "5x8".

       --help, -h
           Show basic help text and exit

       --list '[tag]', -L '[tag]'
           List available cluster tags. Tag is optional.  If a tag is provided
           then hosts for that tag are listed.  NOTE: format of output changes
           when using "--quiet" or "-Q" option.

       --man, -H
           Show full help text (the man page) and exit

       --options '<STRING>', -o '<STRING>'
           Specify arguments to be passed to ssh when making the connection.
           NOTE: options for ssh should normally be put into the ssh
           configuration file; see "ssh_config" and $HOME/.ssh/config for more

           Default: -x -o ConnectTimeout=10

       --port <port>, -p <port>
           Specify an alternate port for connections.

       --quiet, -Q
           Do not output extra text when using some options

       --show-history, -s
           Show history within console window.

       --tag-file '<filename>', -r '<filename>'
           Use supplied file as additional tag file (see also "FILES")

       --term-args '<STRING>', -t '<STRING>'
           Specify arguments to be passed to terminals being used.

       --tile, -g
           Toggle window tiling (overriding the config file).

       --title '<title>', -T '<title>'
           Specify the initial part of the title used in the console and
           client windows.

       --unique-servers, -u
           Toggle connecting to each host only once when a hostname has been
           specified multiple times.

       --usage, -?
           Show synopsis and exit

       --use-all-a-records, -A
           If a hostname resolves to multiple IP addresses, toggle whether or
           not to connect to all of them, or just the first one (see also
           config file entry).

       --username '<username>', -l '<username>'
           Specify the default username to use for connections (if different
           from the currently logged in user).  NOTE: will be overridden by

       --version, -v
           Show version information and exit

       The following arguments are supported:

       [user@]<hostname>[:port] ...
           Open an xterm to the given hostname and connect to the
           administration console.  The optional port number can be used if
           the server is not listening on the standard port.

       <tag> ...
           Open a series of xterms defined by <tag> in one of the
           supplementary configuration files (see "FILES").

           Note: specifying a username on a cluster tag will override any
           usernames defined in the cluster.

       The following key shortcuts are available within the console window,
       and all of them may be changed via the configuration files.

           Open the 'Add Host(s) or Cluster(s)' dialogue box.  Multiple host
           or cluster names can be entered, separated by spaces.

           Paste in the hostname part of the specific connection string to
           each client, minus any username or port, e.g.

           "scp /etc/hosts server:files/<Alt-n>.hosts"

           would replace the <Alt-n> with the client's name in each window.

           Paste in the hostname of the server cssh is being run on

           Quit the program and close all connections and windows.

           Retile all the client windows.

           Paste in the username for the connection

       Open up a session to 3 servers

       Open up a session to a cluster of servers identified by the tag 'farm1'
       and give the controlling window a specific title, where the tag is
       defined in one of the default configuration files

       Connect to different servers using different login names.  NOTE: this
       can also be achieved by setting up appropriate options in the
       configuration files.  Do not close the console when the last terminal

       Open up a cluster defined in a non-default configuration file

       Override the configured/default port to use 2022 instead

       /etc/clusters, $HOME/.clusterssh/clusters
           These files contain a list of tags to server names mappings.  When
           any name is used on the command line it is checked to see if it is
           a tag.  If it is a tag, then the tag is replaced with the list of
           servers.  The format is as follows:



               # List of servers in live
               live admin1@server1 admin2@server2:2022 server3 server4

           All comments (marked by a #) and blank lines are ignored.  Tags may
           be nested, but be aware of using recursive tags as they are not
           checked for.

           Servers can be defined using expansion macros:

           "webservers websvr{a,b,c}"

           would be expanded to

           "webservers websvra websvrb websvrc"


           "webservers websvr{6..9}"

           would be expanded to

           "webservers websvr6 websvr7 websvr8 websvr9"

           Extra cluster files may also be specified either as an option on
           the command line (see "cluster-file") or in the user's
           $HOME/.clusterssh/config file (see "extra_cluster_file"
           configuration option).

           NOTE: the last tag read overwrites any pre-existing tag of that

           NOTE: there is a special cluster tag called "default" - any tags or
           hosts included within this tag will be automatically opened if
           nothing is specified on the command line.

       /etc/tags, $HOME/.clusterssh/tags
           Very similar to clusters files but the definition is reversed.  The
           format is:


           This allows one host to be specified as a member of a number of
           tags.  This format can be clearer than using clusters files.

           Extra tag files may be specified either as an option (see
           "tag-file") or within the user's $HOME/.clusterssh/config file (see
           "extra_tag_file" configuration option).

           NOTE: All tags are added together

       /etc/csshrc & $HOME/.clusterssh/config
           This file contains configuration overrides - the defaults are as
           marked.  Default options are overwritten first by the global file,
           and then by the user file.

           NOTE: values for entries do not need to be quoted unless it is
           required for passing arguments, e.g.

           "terminal_allow_send_events="-xrm '*.VT100.allowSendEvents:true'""

           should be written as

           "terminal_allow_send_events=-xrm '*.VT100.allowSendEvents:true'"

           auto_close = 5
               Close terminal window after this many seconds.  If set to 0
               will instead wait on input from the user in each window before
               closing. See also --autoclose and --no-autoclose

           auto_quit = 1
               Automatically quit after the last client window closes.  Set to
               0 to disable.  See also --autoquit

           auto_wm_decoration_offsets = no
               Enable or disable alternative algorithm for calculating
               terminal positioning.

           comms = ssh
               Sets the default communication method (initially taken from the
               name of the program, but can be overridden here).

           console_position = <null>
               Set the initial position of the console - if empty then let the
               window manager decide.  Format is '+<x>+<y>', i.e. '+0+0' is
               top left hand corner of the screen, '+0-70' is bottom left hand
               side of screen (more or less).

           external_cluster_command = <null>
               Define the full path to an external command that can be used to
               resolve tags to host names.  This command can be written in any
               language.  The script must accept a list of tags to resolve and
               output a list of hosts (space separated on a single line).  Any
               tags that cannot be resolved should be returned unchanged.

               A non-0 exit code will be counted as an error, a warning will
               be printed and output ignored.

               If the external command is given a "-L" option it should output
               a list of tags (space separated on a single line) it can

           extra_cluster_file = <null>
               Define an extra cluster file in the format of /etc/clusters.
               Multiple files can be specified, separated by commas.  Both ~
               and $HOME are acceptable as a reference to the user's home
               directory, e.g.

               "extra_cluster_file = ~/clusters, $HOME/clus"

           extra_tag_file = <null>
               Define an extra tag file in the format of /etc/tags.  Multiple
               files can be specified, separated by commas.  Both ~ and $HOME
               are acceptable as a reference to the user's home directory,

               "extra_tag_file = ~/tags, $HOME/tags"

           key_addhost = Control-Shift-plus
               Default key sequence to open AddHost menu.  See "KEY SHORTCUTS"
               for more information.

           hide_menu = 0
               If set to 1, hide the menu bar (File, Hosts, Send, Help) in the

           key_clientname = Alt-n
               Default key sequence to send cssh client names to client.  See
               "KEY SHORTCUTS" for more information.

           key_localname = Alt-l
               Default key sequence to send hostname of local server to
               client.  See "KEY SHORTCUTS" for more information.

           key_paste = Control-v
               Default key sequence to paste text into the console window.
               See "KEY SHORTCUTS" for more information.

           key_quit = Control-q
               Default key sequence to quit the program (will terminate all
               open windows).  See "KEY SHORTCUTS" for more information.

           key_retilehosts = Alt-r
               Default key sequence to retile host windows.  See "KEY
               SHORTCUTS" for more information.

           key_username = Alt-u
               Default key sequence to send username to client.  See "KEY
               SHORTCUTS" for more information.

           macro_servername = %s
           macro_hostname = %h
           macro_username = %u
           macro_newline = %n
           macro_version = %v
               Change the replacement macro used when either using a 'Send'
               menu item, or when pasting text into the main console.

           macros_enabled = yes
               Enable or disable macro replacement.  Note: this affects all
               the "macro_*" variables above.

           max_addhost_menu_cluster_items = 6
               Maximum number of entries in the 'Add Host' menu cluster list
               before scrollbars are used

           max_host_menu_items = 30
               Maximum number of hosts to put into the host menu before
               starting a new column

           menu_host_autotearoff = 0
           menu_send_autotearoff = 0
               When set to non-0 will automatically tear-off the host or send
               menu at program start

           mouse_paste = Button-2 (middle mouse button)
               Default key sequence to paste text into the console window
               using the mouse.  See "KEY SHORTCUTS" for more information.

           rsh = /path/to/rsh
           ssh = /path/to/ssh
           telnet = /path/to/telnet
               Set the path to the specific binary to use for the
               communication method, else uses the first match found in $PATH

           rsh_args = <blank>
           ssh_args = "-x -o ConnectTimeout=10"
           telnet_args = <blank>
               Sets any arguments to be used with the communication method
               (defaults to ssh arguments).

               NOTE: The given defaults are based on OpenSSH, not commercial
               ssh software.

               NOTE: Any "generic" change to the method (e.g., specifying the
               ssh port to use) should be done in the medium's own config file
               (see "ssh_config" and $HOME/.ssh/config).

           screen_reserve_top = 0
           screen_reserve_bottom = 60
           screen_reserve_left = 0
           screen_reserve_right = 0
               Number of pixels from the screen's side to reserve when
               calculating screen geometry for tiling.  Setting this to
               something like 50 will help keep cssh from positioning windows
               over your window manager's menu bar if it draws one at that
               side of the screen.

           terminal = /path/to/xterm
               Path to the X-Windows terminal used for the client.

           terminal_args = <blank>
               Arguments to use when opening terminal windows.  Otherwise
               takes defaults from $HOME/.Xdefaults or $HOME/.Xresources file.

           terminal_chdir = 0
               When non-0, set the working directory for each terminal as per

           terminal_chdir_path = $HOME/.clusterssh/work/%s
               Path to use as working directory for each terminal when
               'terminal_chdir' is enabled.  The path provided is passed
               through the macro parser (see the section above on

           terminal_font = 6x13
               Font to use in the terminal windows.  Use standard X font

           terminal_reserve_top = 5
           terminal_reserve_bottom = 0
           terminal_reserve_left = 5
           terminal_reserve_right = 0
               Number of pixels from the terminal's side to reserve when
               calculating screen geometry for tiling.  Setting these will
               help keep cssh from positioning windows over your scroll and
               title bars or otherwise overlapping the windows too much.

           terminal_colorize = 1
               If set to 1 (the default), then "-bg" and "-fg" arguments will
               be added to the terminal invocation command-line.  The terminal
               will be colored in a pseudo-random way based on the host name;
               while the color of a terminal is not easily predicted, it will
               always be the same color for a given host name.  After a while,
               you will recognize hosts by their characteristic terminal

           terminal_bg_style = dark
               If set to "dark", the terminal background will be set to black
               and the foreground to the pseudo-random color.  If set to
               "light", then the foreground will be black and the background
               the pseudo-random color.  If terminal_colorize is "zero", then
               this option has no effect.

           terminal_size = 80x24
               Initial size of terminals to use. NOTE: the number of lines
               (24) will be decreased when resizing terminals for tiling, not
               the number of characters (80).

           terminal_title_opt = -T
               Option used with "terminal" to set the title of the window

           terminal_allow_send_events = -xrm '*.VT100.allowSendEvents:true'
               Option required by the terminal to allow XSendEvents to be

           title = cssh
               Title of windows to use for both the console and terminals.

           unmap_on_redraw = no
               Tell Tk to use the UnmapWindow request before redrawing
               terminal windows.  This defaults to "no" as it causes some
               problems with the FVWM window manager.  If you are experiencing
               problems with redraws, you can set it to "yes" to allow the
               window to be unmapped before it is repositioned.

           use_all_a_records = 0
               If a hostname resolves to multiple IP addresses, set to 1 to
               connect to all of them, not just the first one found.  See also

           use_hotkeys = 1
               Setting to 0 will disable all hotkeys.

           use_natural_sort = 0
               Windows will normally sort in alphabetical order, i.e.: host1,
               host11, host2.  Setting to this 1 will change the sort order,
               i.e.: host1, host2, host11. NOTE: You must have the perl module
               Sort::Naturally installed.

           user = $LOGNAME
               Sets the default user for running commands on clients.

           window_tiling = 1
               Perform window tiling (set to 0 to disable)

           window_tiling_direction = right
               Direction to tile windows, where "right" means starting top
               left and moving right and then down, and anything else means
               starting bottom right and moving left and then up

           NOTE: The key shortcut modifiers must be in the form "Control",
           "Alt" or "Shift", e.g. with the first letter capitalised and the
           rest lower case.  Keys may also be disabled individually by setting
           to the word "null".

           This (optional) file contains items to populate the send menu.  The
           default entry could be written as:

               <menu title="Use Macros">
               <menu title="Remote Hostname">
               <menu title="Local Hostname">
               <menu title="Username">
               <menu title="Test Text">
                   <command>echo "ClusterSSH Version: %v%n</command>

           Submenus can also be specified as follows:

               <menu title="Default Entries">
                 <menu title="Hostname">


           There is currently no strict format checking of this file.
           The format of the file may change in the future
           If the file exists, the default entry (Hostname) is not added

           The following replacement macros are available (note: these can be
           changed in the configuration file):

           %s  Hostname part of the specific connection string to each client,
               minus any username or port

           %u  Username part of the connection string to each client

           %h  Hostname of server where cssh is being run from

           %n  "RETURN" code

           NOTE: requires XML::Simple to be installed

       If you have any ideas about how to fix the below bugs, please get in
       touch and/or provide a patch.

       o   Swapping virtual desktops can cause a redraw of all the terminal
           windows.  This is due to a lack of distinction within Tk between
           switching desktops and minimising/maximising windows.  Until Tk can
           tell the difference between the two events, there is no fix (apart
           from rewriting everything directly in X).

       o   If you have issues running cssh, first try:

           "cssh -e [user@]<hostname>[:port]"

           This performs two tests to confirm cssh is able to work properly
           with the settings provided within the $HOME/.clusterssh/config file
           (or internal defaults).

           1.  Test the terminal window works with the options provided

           2.  Test ssh works to a host with the configured arguments

           Configuration options to watch for in ssh are

           SSH doesn't understand "-o ConnectTimeout=10" - remove the option
           from the $HOME/.clusterssh/config file
           OpenSSH-3.8 using untrusted ssh tunnels - use "-Y" instead of "-X"
           or use "ForwardX11Trusted yes" in $HOME/.ssh/ssh_config (if you
           change the default ssh options from "-x" to "-X")
       o   If you require support, please run the following commands and post
           it on the web site in the support/problems forum:

           "perl -V"

           "perl -MTk -e 'print $Tk::VERSION,$/'"

           "perl -MX11::Protocol -e 'print $X11::Protocol::VERSION,$/'"

           "cat /etc/csshrc $HOME/.clusterssh/config"

       o   Using the debug option (--debug) will turn on debugging output.
           Repeat the option to increase the amount of debug.  However, if
           possible please only use this option with one host at a time, e.g.
           "cssh --debug <host>" due to the amount of output produced (in both
           main and child windows).

       See attributes(7) for descriptions of the following attributes:

       |Availability   | terminal/cssh-532 |
       |Stability      | Uncommitted       |

       <http://clusterssh.sourceforge.net/>, "ssh", Tk::overview,
       X11::Protocol, "perl"

       A web site for comments, requests, bug reports and bug fixes/patches is
       available at: <https://github.com/duncs/clusterssh>

       Duncan Ferguson, "<duncan_j_ferguson at yahoo.co.uk>"

       Copyright 1999-2016 Duncan Ferguson.

       This program is free software; you can redistribute it and/or modify it
       under the terms of either: the GNU General Public License as published
       by the Free Software Foundation; or the Artistic License.

       See http://dev.perl.org/licenses/ for more information.

       Source code for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-

       This software was built from source available at
       https://github.com/oracle/solaris-userland.  The original community
       source was downloaded from

       Further information about this software can be found on the open source
       community website at https://sourceforge.net/projects/clusterssh/.

perl v5.32.0                      2022-06-28                           CSSH(1)