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    cssh - Cluster administration tool

    This documentation is for version: 4.16

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

    Also see the individual man pages for each of these utilities

    ccon - Use 'console' as the communication method
    crsh - Use 'rsh' as the communication method
    csftp - Use 'sftp' as the communication method
    ctel - Use 'telnet' as the communication method

    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 directly.

    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".

    *   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.

    *   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.

    *   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").

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

    *   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.

    *   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 quitting 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").

    --cols <cols>, -x <cols>
        Number of columns

    --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

        Resize terminal windows to fill the whole available screen

    --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

    --rows <rows>, -y <rows>
        Number of rows

    --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

    --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

        Run the matching user defined macro on the server and send the
        output to the client

    Open up a session to 3 servers
        $ cssh server1 server2 server3

    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
        $ cssh -T 'Web Farm Cluster 1' farm1

    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 exits.
        $ cssh user1@server1 admin@server2

    Open up a cluster defined in a non-default configuration file
        $ cssh -c $HOME/cssh.extra_clusters db_cluster

    Override the configured/default port to use 2022 instead
        $ cssh -p 2022 server1 server2

    /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:

        <tag> [user@]<server>[:port] [user@]<server>[:port] [...]


            # 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:

        <host> <tag> [...]

        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

        command_pre =
        command_post =
            Add extra commands around the communication method. For example:

            command_pre= . $HOME/virtualenvs/default/bin/active ;
            command_post= | ct

            would allow for using Python virtual envronments and then piping
            all shell output through "chromaterm" for syntax highlighting.
            Note: you must use appropriate command separators/terminators to
            keep the meaning of the command pipline (such as ";" and "|"
            between commands).

            These are not put through macro parsing.

        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_command_mode = 0600
            File mode bits for the external_command_pipe.

        external_command_pipe = <null>
            Define the full path to an external command pipe that can be
            written to for controlling some aspects of ClusterSSH, such as
            opening sessions to more clusters.


            "open <tag|hostname>" - open new sessions to provided tag or

            "retile" - force window retiling

            e.g.: "echo 'open localhost'" /path/to/external_command_pipe >>

        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 resolve

        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, e.g.

            "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.

        key_user_1 = Alt-1
        key_user_2 = Alt-2
        key_user_3 = Alt-3
        key_user_4 = Alt-4
            Default key sequence to send user defined macros to client. If
            the matching macro_user_1 macro is undefined, the sequence is
            passed straight to the terminal. See "KEY SHORTCUTS" for more

        macro_servername = %s
        macro_hostname = %h
        macro_username = %u
        macro_newline = %n
        macro_version = %v
        macro_user_1 = %1
        macro_user_2 = %2
        macro_user_3 = %3
        macro_user_4 = %4
            Change the replacement macro used when either using a 'Send'
            menu item, or when pasting text into the main console.

        macro_user_1_command =
        macro_user_2_command =
        macro_user_3_command =
        macro_user_4_command =
            User defined macros - the macro is run through the shell on the
            server and the output is sent to the client. For example,

            "macro_user_1_command=echo echo macro_user_1"

                        would send the text C<echo macro_user_1> into the terminal session.

            "macro_user_1_command=env | grep CSSH"

                        would send the CSSH environment variables to the client.

            The following environment variables are set in the shell of the
            macro process


        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 'macros_enabled'.

        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 color.

        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.

    *   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).

    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")

    A web site for comments, requests, bug reports and bug fixes/patches is
    available at: <>

    If you require support, please run the following commands and create an
    issue via: <>

    "perl -V"

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

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

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

    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).

    <>, "ssh", Tk::overview,
    X11::Protocol, "perl"

    Duncan Ferguson, "<duncan_j_ferguson at>"

    Copyright 1999-2018 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 for more information.