This file is written in reverse chronological order, newer releases will appear at the top.


  • Your contribution here!

1.18.0 (2018-10-21)

  • #435: Consistent verbosity configuration #capture and #test methods - @NikolayRys

1.17.0 (2018-07-07)

  • #430: [Feature] Command Argument STDOUT/capistrano.log Hiding - @NorseGaud

1.16.1 (2018-05-20)

  • #425: Command#group incorrectly escapes double quotes, resulting in a a syntax error when specifying the group execution using as. This issue manifested when user command quotes changed from double quotes to single quotes. This fix removes the double quote escaping - @pblesi.

1.16.0 (2018-02-03)

  • #417: Cache key generation for connections becomes slow when known_hosts is a valid net/ssh options and known_hosts file is big. This changes the cache key generation and fixes performance issue - @ElvinEfendi.

1.15.1 (2017-11-18)

This is a small bug-fix release that fixes problems with upload! and download! that were inadvertently introduced in 1.15.0.

Breaking changes

  • None

Bug fixes

  • #410: fix NoMethodError when using upload!/download! with Pathnames - @UnderpantsGnome
  • #411: fix upload!/download! when using relative paths outside of within blocks - @Fjan

1.15.0 (2017-11-03)

New features

  • #408: upload! and download! now respect within - @sj26

Potentially breaking changes

  • upload! and download! now support remote paths which are relative to the within working directory. They were previously documented as only supporting absolute paths, but relative paths still worked relative to the remote working directory. If you rely on the previous behaviour you may need to adjust your code.

1.14.0 (2017-06-30)

Breaking changes

  • None

New features

  • #401: Add :log_percent option to specify upload!/download! transfer log percentage - @aubergene

1.13.1 (2017-03-31)

Breaking changes

  • None

Bug fixes

  • #397: Fix NoMethodError assign_defaults with net-ssh older than 4.0.0 - @shirosaki

1.13.0 (2017-03-24)

Breaking changes

  • None

New features

Bug fixes

1.12.0 (2017-02-10)

Breaking changes

  • None

New features

  • Add SSHKit.config.default_runner_config option that allows overriding default runner configs.

1.11.5 (2016-12-16)

Bug fixes

  • Do not prefix exec command PR #378 @dreyks

1.11.4 (2016-11-02)

  • Use string interpolation for environment variables to avoid escaping issues with sprintf PR #280 @Sinjo - Chris Sinjakli

1.11.3 (2016-09-16)

  • Fix known_hosts caching to match on the entire hostlist PR #364 @byroot

1.11.2 (2016-07-29)

Bug fixes

1.11.1 (2016-06-17)

Bug fixes

  • Fixed a regression in 1.11.0 that would cause ArgumentError: invalid option(s): known_hosts in some older versions of net-ssh. @byroot #357

1.11.0 (2016-06-14)

Bug fixes

  • Fixed colorized output alignment in Logger::Pretty. @xavierholt PR #349
  • Fixed a bug that prevented nested with calls #43

Other changes

  • Known hosts lookup optimization is now enabled by default. @byroot

1.10.0 (2016-04-22)

  • You can now opt-in to caching of SSH's known_hosts file for a speed boost when deploying to a large fleet of servers. Refer to the README for details. We plan to turn this on by default in a future version of SSHKit. PR #330 @byroot
  • SSHKit now explicitly closes its pooled SSH connections when Ruby exits; this fixes zlib(finalizer): the stream was freed prematurely warnings PR #343 @mattbrictson
  • Allow command map entries (SSHKit::CommandMap#[]) to be Procs PR #310 @mikz


Refer to the 1.9.0.rc1 release notes for a full list of new features, fixes, and potentially breaking changes since SSHKit 1.8.1. There are no changes since 1.9.0.rc1.


Potentially breaking changes

  • The SSHKit DSL is no longer automatically included when you require it. This means you must now explicitly include SSHKit::DSL. See PR #219 for details. @beatrichartz
  • SSHKit::Backend::Printer#test now always returns true PR #312 @mikz

New features

  • SSHKit::Formatter::Abstract now accepts an optional Hash of options PR #308 @mattbrictson
  • Add SSHKit::Backend.current so that Capistrano plugin authors can refactor helper methods and still have easy access to the currently-executing Backend without having to use global variables.
  • Add SSHKit.config.default_runner options that allows to override default command runner. This option also accepts a name of the custom runner class.
  • The ConnectionPool has been rewritten in this release to be more efficient and have a cleaner internal API. You can still completely disable the pool by setting SSHKit::Backend::Netssh.pool.idle_timeout = 0. @mattbrictson @byroot PR #328

Bug fixes

  • make sure working directory for commands is properly cleared after within blocks PR #307 @steved
  • display more accurate string for commands with spaces being output in Formatter::Pretty PR #304 @steved PR #319 @mattbrictson
  • Fix a race condition experienced in JRuby that could cause multi-server deploys to fail. PR #322 @mattbrictson


  • Change license to MIT, thanks to all the patient contributors who gave their permissions.


  • add SSHKit::Backend::ConnectionPool#close_connections PR #285 @akm
  • Clean up rubocop lint warnings PR #275 @cshaffer
    • Prepend unused parameter names with an underscore
    • Prefer “safe assignment in condition”
    • Disambiguate regexp literals with parens
    • Prefer sprintf over String#%
    • No longer shadow caller_line variable in DeprecationLogger
    • Rescue StandardError instead of Exception
    • Remove useless private access modifier in TestAbstract
    • Disambiguate block operator with parens
    • Disambiguate between grouped expression and method params
    • Remove assertion in TestHost#test_assert_hosts_compare_equal that compares something with itself
  • Export environment variables and execute command in a subshell. PR #273 @kuon
  • Introduce log_command_start, log_command_data, log_command_exit methods on Formatter PR #257 @robd
    • Deprecate @stdout and @stderr accessors on Command
  • Add support for deprecation logging options. README, PR #258 @robd
  • Quote environment variable values. PR #250 @Sinjo - Chris Sinjakli
  • Simplified formatter hierarchy. PR #248 @robd
    • SimpleText formatter now extends Pretty, rather than duplicating.
  • Hide ANSI color escape sequences when outputting to a file. README, Issue #245, PR #246 @robd
    • Now only color the output if it is associated with a tty, or the SSHKIT_COLOR environment variable is set.
  • Removed broken support for assigning an IO to the output config option. Issue #243, PR #244 @robd
    • Use SSHKit.config.output =$stdin) instead
  • Added support for :interaction_handler option on commands. PR #234, PR #242 @robd
  • Removed partially supported TRACE log level. 2aa7890 @robd
  • Add support for the :strip option to the capture method and strip by default on the Local backend. PR #239, PR #249 @robd
    • The Local backend now strips by default to be consistent with the Netssh one.
    • This reverses change 7d15a9a to the Local capture API to remove stripping by default.
    • If you require the raw, unstripped output, pass the strip: false option: capture(:ls, strip: false)
  • Simplified backend hierarchy. PR #235, PR #237 @robd
    • Moved duplicate implementations of make, rake, test, capture, background on to Abstract backend.
    • Backend implementations now only need to implement execute_command, upload! and download!
    • Removed Printer from backend hierarchy for Local and Netssh backends (they now just extend Abstract)
    • Removed unused Net::SSH:LogLevelShim
  • Removed dependency on the colorize gem. SSHKit now implements its own ANSI color logic, with no external dependencies. Note that SSHKit now only supports the :bold or plain modes. Other modes will be gracefully ignored. #263
  • New API for setting the formatter: use_format. This differs from format= in that it accepts options or arguments that will be passed to the formatter's constructor. The format= syntax will be deprecated in a future release. #295
  • SSHKit now immediately raises a NameError if you try to set a formatter that does not exist. #295
  • Fix error message when the formatter does not exist. #301


  • Fix a regression in 1.7.0 that caused command completion messages to be removed from log output. @mattbrictson


  • Update Vagrantfile to use multi-provider Hashicorp precise64 box - remove URLs. @townsen
  • Merge host ssh_options and Netssh defaults @townsen Previously if host-level ssh_options were defined the Netssh defaults were ignored.
  • Merge host ssh_options and Netssh defaults
  • Fixed race condition where output of failed command would be empty. @townsen Caused random failures of test_execute_raises_on_non_zero_exit_status_and_captures_stdout_and_stderr Also fixes output handling in failed commands, and generally buggy output.
  • Remove override of backtrace() and backtrace_locations() from ExecuteError. @townsen This interferes with rake default behaviour and creates duplicate stacktraces.
  • Allow running local commands using on(:local)
  • Implement the upload! and download! methods for the local backend


  • Fix colorize to use the correct API (@fazibear)
  • Lock colorize (sorry guys) version at >= 0.7.0

1.6.0 (Yanked, because of colorize.)

  • Force dependency on colorize v0.6.0
  • Add your entries here, remember to credit yourself however you want to be credited!
  • Remove strip from capture to preserve whitespace. Nick Townsend
  • Add vmware_fusion Vagrant provider. Nick Townsend
  • Add some padding to the pretty log formatter


  • Use sudo -u rather than sudo su to switch users. Mat Trudel


  • Deprecate background helper - too many badly behaved pseudo-daemons. Lee Hambley
  • Don't colourize unless $stdout is a tty. Lee Hambley
  • Remove out of date "Known Issues" section from README. Lee Hambley
  • Dealy variable interpolation inside as() block. Nick Townsend
  • Fixes for functional tests under modern Vagrant. Lewis Marshal
  • Fixes for connection pooling. Chris Heald
  • Add localhost hostname to local backend. Adam Mckaig
  • Wrap execptions to include hostname. Brecht Hoflack
  • Remove shellwords stdlib dependency Bruno Sutic
  • Remove unused cooldown accessor. Bruno Sutic
  • Replace Term::ANSIColor with a lighter solution. Tom Clements
  • Documentation fixes. Matt Brictson


  • Removed invoke alias for SSHKit::Backend::Printer.execute. This is to prevent collisions with methods in capistrano with similar names, and to provide a cleaner API. See capistrano issue 912 and issue 107 for more details.
  • Connection pooling now uses a thread local to store connection pool, giving each thread its own connection pool. Thank you @mbrictson see #101 for more.
  • Command map indifferent towards strings and symbols thanks to @thomasfedb see #91
  • Moved vagrant wrapper to support directory, added ability to run tests with vagrant using ssh. @miry see #64
  • Removed unnecessary require require_relative '../sshkit' in lib/sshkit/dsl.rb prevents warnings thanks @brabic.
  • Doc fixes thanks @seanhandley @vojto


  • Connection pooling. SSH connections are reused across multiple invocations of on(), which can result in significant performance gains. See: Matt @mbrictson Brictson.
  • Fixes to the Formatter::Dot and to the formatter class name resolver. @hab287:w
  • Added the license to the Gemspec. @anatol.
  • Fix :limit handling for the in: :groups run mode. Phil @phs Smith
  • Doc fixes @seanhandley, @sergey-alekseev.


  • Support picking up a project local SSH config file, if a SSH config file exists at ./.ssh/config it will be merged with the ~/.ssh/config. This is ideal for defining project-local proxies/gateways, etc. Thanks to Alex @0rca Vzorov.
  • Tests and general improvements to the Printer backends (mostly used internally). Thanks to Michael @miry Nikitochkin.
  • Update the net-scp dependency version. Thanks again to Michael @miry Nikitochkin.
  • Improved command map. This feature allows mapped variables to be pushed and unshifted onto the mapping so that the Capistrano extensions for rbenv and bundler, etc can work together. For discussion about the reasoning see and A big thanks to Kir @kirs Shatrov.
  • test() and capture() now behave as expected inside a run_locally block meaning that they now run on your local machine, rather than erring out. Thanks to Kentaro @kentaroi Imai.
  • The :wait option is now successfully passed to the runner now. Previously the :wait option was ignored. Thanks to Jordan @jhollinger Hollinger for catching the mistake in our test coverage.
  • Fixes and general improvements to the download() method which until now was quite naïve. Thanks to @chqr.


  • Please see the Git history. git rebase ate our changelog (we should have been more careful)


  • The gem now supports a run_locally, although it's nothing to do with SSH, it makes a nice API. There are examples in the


  • Allow the setting of global SSH options on the backend.ssh as a hash, these options are the same as Net::SSH configure expects. Thanks to Rafał @lisukorin Lisowski


  • Lots of small changes since 0.0.27.
  • Particularly working around a possible NaN issue when uploading comparatively large files.


  • Don't clobber SSH options with empty values. This allows Net::SSH to do the right thing most of the time, and look into the SSH configuration files.


  • Pretty output no longer prints white text. ("Command.....")
  • Fixed a double-output bug, where upon receiving the exit status from a remote command, the last data packet that it sent would be re-printed by the pretty formatter.
  • Integration tests now use an Ubuntu Precise 64 Vagrant base box.
  • Additional host declaration syntax, SSHKit::Host can now take a hash of host properties in addition to a number of new (common sense) DSN type syntaxes.
  • Changes to the constants used for logging, we no longer re-define a Logger::TRACE constant on the global Logger class, rather everyhing now uses SSHKit::Logger (Thanks to Rafa Garcia)
  • Various syntax and documentation fixes.


  • upload! and download! now log to different levels depending on completion percentage. When the upload is 0 percent complete or a number indivisible by 10, the message is logged to Logger::DEBUG otherwise the message is logged to Logger::INFO, this should mean that normal users at a sane log level should see upload progress jump to 100% for small files, and otherwise for larger files they'll see output every 10%.


  • Pretty output now streams stdout and stderr. Previous versions would append (+=) chunks of data written by the remote host to the Command instance, and the Pretty formatter would only print stdout/stderr if the command was #complete?. Historically this lead to issues where the remote process was blocking for input, had written the prompt to stdout, but it was not visible on the client side.

    Now each time the command is passed to the output stream, the stdout/stderr are replaced with the lines returned from the remote server in this chunk. (i.e were yielded to the callback block). Commands now have attribute accessors for #full_stdout and #full_stderr which are appended in the way that #stdout and #stderr were previously.

    This should be considered a private API, and one should beware of relying on #full_stdout or #full_stderr, they will likely be replaced with a cleaner soltion eventually.

  • upload! and download! now print progress reports at the Logger::INFO verbosity level.


  • Explicitly rely on net-scp gem.


  • Added naïve implementations of upload!() and download!() (syncoronous) to the Net::SSH backend. See for more extensive usage examples.

    The upload!() method can take a filename, or an IO, this reflects the way the underlying Net::SCP implementation works. The same is true of download!(), when called with a single argument it captures the file's contents, otherwise it downloads the file to the local disk.

    on hosts do |host|
      upload!('some-data-here'), '~/.ssh/authorized_keys')
      upload!('~/.ssh/', '~/.ssh/authorized_keys')
      puts download!('/etc/monit/monitrc')
      download!('/etc/monit/monitrc', '~/monitrc')


  • Fixed an issue with default formatter
  • Modified SSHKit.config.output_verbosity= to accept different objects:

    SSHKit.config.output_verbosity = Logger::INFO
    SSHKit.config.output_verbosity = :info
    SSHKit.config.output_verbosity = 1


  • Fixed a bug where the log level would be assigned, not compared in the pretty formatter, breaking the remainder of the output verbosity.


  • Modified the Pretty formatter to include the log level in front of executed commands.

  • Modified the Pretty formatter not to print stdout and stderr by default, the log level must be raised to Logger::DEBUG to see the command outputs.

  • Modified the Pretty formatter to use Command#to_s when printing the command, this prints the short form (without modifications/wrappers applied to the command for users, groups, directories, umasks, etc).


  • Enable as() to take either a string/symbol as previously, but also now accepts a hash of {user: ..., group: ...}. In case that your host system supports the command sg (man 1 sg) to switch your effective group ID then one can work on files as a team group user.

    on host do |host|
      as user: :peter, group: griffin do
        execute :touch, 'somefile'

    will result in a file with the following permissions:

    -rw-r--r-- 1 peter griffin 0 Jan 27 08:12 somefile

    This should make it much easier to share deploy scripts between team members.

    Note: sg has some very strict user and group password requirements (the user may not have a password (passwd username -l to lock an account that already has a password), and the group may not have a password.)

    Additionally, and unsurprisingly the user must also be a member of the group.

    sg was chosen over newgrp as it's easier to embed in a one-liner command, newgrp could be used with a heredoc, but my research suggested that it might be better to use sg, as it better represents my intention, a temporary switch to a different effective group.

  • Fixed a bug with environmental variables and umasking introduced in 0.0.14. Since that version the environmental variables were being presented to the umask command's subshell, and not to intended command's subshell.

    incorrect: ENV=var umask 002 && env correct: umask 002 && ENV=var env

  • Changed the exception handler, if a command returns with a non-zero exit status then the output will be prefixed with the command name and which channel any output was written to, for example:"echo ping; false") => echo stdout: ping echo stderr: Nothing written

In this contrived example that's more or less useless, however with badly behaved commands that write errors to stdout, and don't include their name in the program output, it can help a lot with debugging.


  • Fixed a bug introduced in 0.0.16 where the capture() helper returned the name of the command that had been run, not it's output.

  • Classify the pre-directory switch, and pre-user switch command guards as having a DEBUG log level to exclude them from the logs.


  • Fixed a bug introduced in 0.0.15 where the capture() helper returned boolean, discarding any output from the server.


  • Command now takes a verbosity option. This defaults to Logger::INFO and can be set to any of the Ruby logger level constants. You can also set it to the symbol :debug (and friends) which will be expanded into the correct constants.

The log verbosity level is set to Logger::INFO by default, and can be overridden by setting SSHKit.config.output_verbosity = Logger::{...}, pick a level that works for you.

By default test() and capture() calls are surpressed, and not printed by the pretty logger as of this version.


  • Umasks can now be set on Command instances. It can be set globally with SSHKit.config.umask (default, nil; meaning take the system default). This can be used to set, for example a umask of 007 for allowing users with the same primary group to share code without stepping on eachother's toes.


  • Correctly quote as(user) commands, previously it would expand to: sudo su user -c /usr/bin/env echo "Hello World", in which the command to run was taken as simply /usr/bin/env. By quoting all arguments it should now work as expected. sudo su user -c "/usr/bin/env echo \""Hello World\""


  • Also print anything the program wrote to stdout when the exit status is non-zero and the command raises an error. (assits debugging badly behaved programs that fail, and write their error output to stdout.)


  • Implementing confuguration objects on the backends (WIP, undocumented)
  • Implement SSHKit.config.default_env, a hash which can be modified and will act as a global with.
  • Fixed #9 (with(a: 'b', c: 'c') being parsed as A=bC=d. Now properly space separated.
  • Fixed #10 (overly aggressive shell escaping), one can now do: `with(path: 'foo:$PATH') without the $ being escaped too early.


  • Include more attributes in Command#to_hash.


  • Include more attributes in Command#to_hash.


  • Added DSL method background() this sends a task to the background using nohup and redirects it's output to /dev/null so as to avoid littering the filesystem with nohup.out files.

Note: Backgrounding a task won't work as you expect if you give it a string, that is you must do background(:sleep, 5) and not background("sleep 5") according to the rules by which a command is not processed in any way if it contains a spaca character in it's first argument.

Usage Example:

on hosts do
  background :rake, "assets:precompile" # typically takes 5 minutes!

Further: Many programs are badly behaved and no not work well with nohup it has to do with the way nohup works, reopening the processe's file descriptors and redirecting them. Programs that re-open, or otherwise manipulate their own file descriptors may lock up when the SSH session is disconnected, often they block writing to, or reading from stdin/out.


  • DSL method execute() will now raise SSHKit::Command::Failed when the exit status is non-zero. The message of the exception will be whatever the process had written to stdout.
  • New DSL method test() behaves as execute() used to until this version.
  • Command now raises an error in #exit_status=() if the exit status given is not zero. (see below)
  • All errors raised by error conditions of SSHKit are defined as subclasses of SSHKit::StandardError which is itself a subclass of StandardError.

The Command objects can be set to not raise, by passing raise_on_non_zero_exit: false when instantiating them, this is exactly what test() does internally.


on hosts do |host
  if test "[ -d /opt/sites ]" do
    within "/opt/sites" do
      execute :git, :pull
    execute :git, :clone, 'some-repository', '/opt/sites'


  • Support arbitrary properties on Host objects. (see below)

Starting with this version, the Host class supports arbitrary properties, here's a proposed use-case:

servers = %w{
   }.collect do |s|
  h =
  if s.match /(one|two)/ = [:web]
  else = [:app]

on servers do |host|
    # Do something pertinent to web servers
    # Do something pertinent to application servers

Naturally, this is a contrived example, the #properties attribute on the Host instance is implemented as an OpenStruct and will behave exactly as such.


  • Removed configuration option SSHKit.config.format (see below)
  • Removed configuration option SSHKit.config.runner (see below)

The format should now be set by doing:

SSHKit.config.output ='/dev/null')
SSHKit.config.output =$stdout)

The library ships with three formatters, BlackHole, Dot and Pretty.

The default is Pretty, but can easily be changed:

SSHKit.config.output =$stdout)
SSHKit.config.output =$stdout)
SSHKit.config.output =$stdout)

The one and only argument to the formatter is the *String/StringIO*ish object to which the output should be sent. (It should be possible to stack formatters, or build a multi-formatter to log, and stream to the screen, for example)

The runner is now set by default_options on the Coordinator class. The default is still :parallel, and can be overridden on the on() (or Coordinator#each) calls directly.

There is no global way to change the runner style for all on() calls as of version 0.0.5.


  • Rename the ConnectionManager class to Coordinator, connections are handled in the backend, if it needs to create some connections.


  • Refactor the runner classes into an abstract heirarchy.


  • Include a Pretty formatter
  • Modify example to use Pretty formatter.
  • Move common behaviour to an abstract formatter.
  • Formatters no longer inherit StringIO


First release.