Polysh

Polysh (formerly called Group Shell or gsh) is a remote shell multiplexer. It lets you control many remote shells at once in a single shell. Unlike other commands dispatchers, it is interactive, so shells spawned on the remote hosts are persistent. It requires only a SSH server on the remote hosts, or some other way to open a remote shell.

Python >= 3.5 is required.

Usage:

polysh [OPTIONS]... HOSTS...

Prompt

The polysh prompt shows either ready (X)> or waiting (X/Y)>. The ready prompt means that all enabled remote shells are ready to receive commands and there are X such remote shells. Failing that, the waiting prompt is shown, meaning that X remote shells are not yet ready to receive commands. Either way, all the readline editing features like navigation in the history, searching in the history, and completion are available.

Commands prefixed by an exclamation mark are executed locally. Signals Ctrl-C and Ctrl-D are forwarded to the remote shells.

The prompt supports completion by pressing the Tab key. Completion results are taken from the command line history, paths from the local filesystem and commands from the user $PATH.

Hostnames with numbers can be generated by polysh using the <START-END> syntax. The generated numbers will be zero padded according to the number of zeroes in the START and END numbers.

Options

--version

Show program`s version number and exit

-h, --help

Show the help message and exit

--hosts-file=FILE

Read hostnames from given file, one per line

Hostnames are given on the command line, but they can also be read from files. The format is one hostname per line, # comments and blank lines are skipped.

--command=CMD

Command to execute on the remote shells

This starts polysh in non-interactive mode. It will start the remote shells, send the command, print the output and exit when the command is completed on all remote shells. This is the same as piping a command on the standard input. Exit codes from the remote shells will be aggregated (taking the max) to form polysh's exit code.

--ssh=SSH

Command to use for SSH

By default, exec ssh -oLogLevel=Quiet -t %(host)s %(port)s. polysh spawns ssh for each connection which may spawn your default login shell on the remote, but another shell command can be specified here. For example, with --ssh='usleep $((RANDOM*50)); exec ssh' a delay will be introduced to avoid all hosts accessing a NFS server at the same time. If the hostname should not be added at the end of the command, the macro %(host)s can be inserted where the hostname should be placed. Also, make sure the command you use launches a pty, this may need the -t option for ssh.

--user=USER

Remote user to log in as

When specified, polysh will ssh to USER@HOST instead of simply HOST.

--no-color

Disable colored hostnames, enabled by default

When specified, polysh will not use tty colors for the hostname prefix.

--password-file=FILE

Read a password from the specified file

- is the tty. This can be used when public key authentication is not available, either write the password in a file, or set FILE to - so that polysh will prompt for a password.

--log-file=LOG_FILE

File to log each machine conversation

If specified, polysh will log all executed commands and their output in the file. The logging destination can be dynamically changed with the :set_log control command.

--abort-errors

Abort if some shell fails to initialize

By default, polysh just logs an error when it cannot successfully open a remote shell. With this option, it exits with a failure.

--debug

Print debugging information

Use this option to see exactly what is transferred between polysh and the remote shells. This option can be dynamically toggled using the :set_debug command in the control shell.

Control Commands

Control commands are special purpose commands prefixed by a colon and directed at polysh itself instead of the remote shells. These commands are:

:add NAMES...

Add one or many remote shells

:chdir LOCAL_PATH

Change the current directory of polysh (not the remote shells)

:disable [SHELLS...]

Disable sending commands to remote shells

If the command would have no effect, it changes all other shells to the inverse enable value. That is, if you disable only already disabled shells, it will first enable all other shells. The special characters *, ?, and [] work as expected.

:enable [SHELLS...]

Enable sending commands to remote shells. If the command would have no effect, it changes all other shells to the inverse enable value. That is, if you enable only already enabled shells, it will first disable all other shells. The special characters *, ?, and [] work as expected.

:export_vars

Export some environment variables on enabled remote shells

POLYSH_NR_SHELLS is the total number of enabled shells. POLYSH_RANK uniquely identifies each shell with a number between 0 and POLYSH_NR_SHELLS - 1. POLYSH_NAME is the hostname as specified on the command line and POLYSH_DISPLAY_NAME the hostname as displayed by :list (most of the time the same as POLYSH_NAME).

:hide_password

Do not echo the next typed line

This is useful when entering password. If debugging or logging is enabled, it will be disabled to avoid displaying a password. Therefore, you will have to re-enable logging or debugging afterwards if need be.

:list [SHELLS...]

List remote shells and their states

The output consists of: <hostname> <enabled?> <state>: <last printed line>. The special characters *, ?, and [] work as expected.

:purge [SHELLS...]

Delete disabled remote shells

This helps to have a shorter list. The special characters *, ?, and [] work as expected.

:quit

Quit polysh

:reconnect [SHELLS...]

Try to reconnect to disconnected remote shells

The special characters *, ?, and [] work as expected.

:rename [NEW_NAME]

Rename all enabled remote shells with the argument

The argument will be shell expanded on the remote processes. With no argument, the original hostname will be restored as the displayed name.

:reset_prompt [SHELLS...]

Change the prompt to be recognized by polysh

The special characters *, ?, and [] work as expected.

:send_ctrl LETTER [SHELLS...]

Send a control character to remote shells

The first argument is the control character to send c or d. Note that these control characters can also be sent simply by typing them. The remaining optional arguments are the destination shells. The special characters *, ?, and [] work as expected.

:set_debug y|n [SHELLS...]

Enable or disable debugging output for remote shells

The first argument is y to enable the debugging output, n to disable it. The remaining optional arguments are the selected shells. The special characters *, ?, and [] work as expected.

:set_log [LOCAL_PATH]

Duplicate every console I/O into the given local file

If LOCAL_PATH is not given, restore the default behaviour of not logging.

:show_read_buffer [SHELLS...]

Print the data read by remote shells

The special characters *, ?, and [] work as expected.

History

The tool is authored by Guillaume Chazarain <guichaz@gmail.com>. The first version released in 2006. It has been maintained by InnoGames GmbH since 2018.