Export environment variables and execute command in a subshell

CHANGELOG.md

@@ -7,6 +7,9 @@ appear at the top.
 
   * Add your entries below here, remember to credit yourself however you want
     to be credited!
+  * Export environment variables and execute command in a subshell.
+    [PR #273](https://github.com/capistrano/sshkit/pull/273)
+    @kuon
   * Introduce `log_command_start`, `log_command_data`, `log_command_exit` methods on `Formatter`
     [PR #257](https://github.com/capistrano/sshkit/pull/257)
     @robd

lib/sshkit/command.rb

@@ -163,7 +163,7 @@ def environment_string
 
     def with(&block)
       return yield unless environment_hash.any?
-      "( #{environment_string} %s )" % yield
+      "( export #{environment_string} ; %s )" % yield
     end
 
     def user(&block)

test/functional/backends/test_netssh.rb

@@ -38,7 +38,7 @@ def test_simple_netssh
           Command: /usr/bin/env ls -l
           Command: if test ! -d /tmp; then echo \"Directory does not exist '/tmp'\" 1>&2; false; fi
           Command: if ! sudo -u root whoami > /dev/null; then echo \"You cannot switch to user 'root' using sudo, please check the sudoers file\" 1>&2; false; fi
-          Command: cd /tmp && ( RAILS_ENV="production" sudo -u root RAILS_ENV="production" -- sh -c '/usr/bin/env touch restart.txt' )
+          Command: cd /tmp && ( export RAILS_ENV="production" ; sudo -u root RAILS_ENV="production" -- sh -c '/usr/bin/env touch restart.txt' )
         EOEXPECTED
       end
 
@@ -62,6 +62,16 @@ def test_ssh_option_merge
         assert_equal({ forward_agent: false, paranoid: true }, host_ssh_options)
       end
 
+      def test_env_vars_substituion_in_subshell
+        captured_command_result = nil
+        Netssh.new(a_host) do |host|
+          with some_env_var: :some_value do
+           captured_command_result = capture(:echo, '$SOME_ENV_VAR')
+          end
+        end.run
+        assert_equal "some_value", captured_command_result
+      end
+
       def test_execute_raises_on_non_zero_exit_status_and_captures_stdout_and_stderr
         err = assert_raises SSHKit::Command::Failed do
           Netssh.new(a_host) do |host|

test/unit/test_command.rb

@@ -28,44 +28,44 @@ def test_using_a_heredoc
     def test_including_the_env
       SSHKit.config = nil
       c = Command.new(:rails, 'server', env: {rails_env: :production})
-      assert_equal %{( RAILS_ENV="production" /usr/bin/env rails server )}, c.to_command
+      assert_equal %{( export RAILS_ENV="production" ; /usr/bin/env rails server )}, c.to_command
     end
 
     def test_including_the_env_with_multiple_keys
       SSHKit.config = nil
       c = Command.new(:rails, 'server', env: {rails_env: :production, foo: 'bar'})
-      assert_equal %{( RAILS_ENV="production" FOO="bar" /usr/bin/env rails server )}, c.to_command
+      assert_equal %{( export RAILS_ENV="production" FOO="bar" ; /usr/bin/env rails server )}, c.to_command
     end
 
     def test_including_the_env_with_string_keys
       SSHKit.config = nil
       c = Command.new(:rails, 'server', env: {'FACTER_env' => :production, foo: 'bar'})
-      assert_equal %{( FACTER_env="production" FOO="bar" /usr/bin/env rails server )}, c.to_command
+      assert_equal %{( export FACTER_env="production" FOO="bar" ; /usr/bin/env rails server )}, c.to_command
     end
 
     def test_double_quotes_are_escaped_in_env
       SSHKit.config = nil
       c = Command.new(:rails, 'server', env: {foo: 'asdf"hjkl'})
-      assert_equal %{( FOO="asdf\\\"hjkl" /usr/bin/env rails server )}, c.to_command
+      assert_equal %{( export FOO="asdf\\\"hjkl" ; /usr/bin/env rails server )}, c.to_command
     end
 
     def test_including_the_env_doesnt_addressively_escape
       SSHKit.config = nil
       c = Command.new(:rails, 'server', env: {path: '/example:$PATH'})
-      assert_equal %{( PATH="/example:$PATH" /usr/bin/env rails server )}, c.to_command
+      assert_equal %{( export PATH="/example:$PATH" ; /usr/bin/env rails server )}, c.to_command
     end
 
     def test_global_env
       SSHKit.config = nil
       SSHKit.config.default_env = { default: 'env' }
       c = Command.new(:rails, 'server', env: {})
-      assert_equal %{( DEFAULT="env" /usr/bin/env rails server )}, c.to_command
+      assert_equal %{( export DEFAULT="env" ; /usr/bin/env rails server )}, c.to_command
     end
 
     def test_default_env_is_overwritten_with_locally_defined
       SSHKit.config.default_env = { foo: 'bar', over: 'under' }
       c = Command.new(:rails, 'server', env: { over: 'write'})
-      assert_equal %{( FOO="bar" OVER="write" /usr/bin/env rails server )}, c.to_command
+      assert_equal %{( export FOO="bar" OVER="write" ; /usr/bin/env rails server )}, c.to_command
     end
 
     def test_working_in_a_given_directory
@@ -75,7 +75,7 @@ def test_working_in_a_given_directory
 
     def test_working_in_a_given_directory_with_env
       c = Command.new(:ls, '-l', in: "/opt/sites", env: {a: :b})
-      assert_equal %{cd /opt/sites && ( A="b" /usr/bin/env ls -l )}, c.to_command
+      assert_equal %{cd /opt/sites && ( export A="b" ; /usr/bin/env ls -l )}, c.to_command
     end
 
     def test_having_a_host_passed
@@ -120,7 +120,7 @@ def test_umask_with_working_directory_and_user
     def test_umask_with_env_and_working_directory_and_user
       SSHKit.config.umask = '007'
       c = Command.new(:touch, 'somefile', user: 'bob', env: {a: 'b'}, in: '/var')
-      assert_equal %{cd /var && umask 007 && ( A="b" sudo -u bob A="b" -- sh -c '/usr/bin/env touch somefile' )}, c.to_command
+      assert_equal %{cd /var && umask 007 && ( export A="b" ; sudo -u bob A="b" -- sh -c '/usr/bin/env touch somefile' )}, c.to_command
     end
 
     def test_verbosity_defaults_to_logger_info