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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 [email protected]. The first version released in 2006. It has been maintained by InnoGames GmbH since 2018.