module Toys::StandardMixins::Exec
A set of helper methods for invoking subcommands. Provides shortcuts for common cases such as invoking Ruby in a subprocess or capturing output in a string. Also provides an interface for controlling a spawned process's streams.
You may make these methods available to your tool by including the following directive in your tool configuration:
include :exec
This is a frontend for {Toys::Utils::Exec}. More information is available in that class's documentation.
### Controlling processes
A process can be started in the foreground or the background. If you start a foreground process, it will “take over” your standard input and output streams by default, and it will keep control until it completes. If you start a background process, its streams will be redirected to null by default, and control will be returned to you immediately.
When a process is running, you can control it using a {Toys::Utils::Exec::Controller} object. Use a controller to interact with the process's input and output streams, send it signals, or wait for it to complete.
When running a process in the foreground, the controller will be yielded to an optional block. For example, the following code starts a process in the foreground and passes its output stream to a controller.
exec(["git", "init"], out: :controller) do |controller| loop do line = controller.out.gets break if line.nil? puts "Got line: #{line}" end end
When running a process in the background, the controller is returned from the method that starts the process:
controller = exec_service.exec(["git", "init"], background: true)
### Stream handling
By default, subprocess streams are connected to the corresponding streams in the parent process. You can change this behavior, redirecting streams or providing ways to control them, using the `:in`, `:out`, and `:err` options.
Three general strategies are available for custom stream handling. First, you may redirect to other streams such as files, IO objects, or Ruby strings. Some of these options map directly to options provided by the `Process#spawn` method. Second, you may use a controller to manipulate the streams programmatically. Third, you may capture output stream data and make it available in the result.
Following is a full list of the stream handling options, along with how to specify them using the `:in`, `:out`, and `:err` options.
* **Inherit parent stream:** You may inherit the corresponding stream in the parent process by passing `:inherit` as the option value. This is the default if the subprocess is *not* run in the background. * **Redirect to null:** You may redirect to a null stream by passing `:null` as the option value. This connects to a stream that is not closed but contains no data, i.e. `/dev/null` on unix systems. This is the default if the subprocess is run in the background. * **Close the stream:** You may close the stream by passing `:close` as the option value. This is the same as passing `:close` to `Process#spawn`. * **Redirect to a file:** You may redirect to a file. This reads from an existing file when connected to `:in`, and creates or appends to a file when connected to `:out` or `:err`. To specify a file, use the setting `[:file, "/path/to/file"]`. You may also, when writing a file, append an optional mode and permission code to the array. For example, `[:file, "/path/to/file", "a", 0644]`. * **Redirect to an IO object:** You may redirect to an IO object in the parent process, by passing the IO object as the option value. You may use any IO object. For example, you could connect the child's output to the parent's error using `out: $stderr`, or you could connect to an existing File stream. Unlike `Process#spawn`, this works for IO objects that do not have a corresponding file descriptor (such as StringIO objects). In such a case, a thread will be spawned to pipe the IO data through to the child process. * **Combine with another child stream:** You may redirect one child output stream to another, to combine them. To merge the child's error stream into its output stream, use `err: [:child, :out]`. * **Read from a string:** You may pass a string to the input stream by setting `[:string, "the string"]`. This works only for `:in`. * **Capture output stream:** You may capture a stream and make it available on the {Toys::Utils::Exec::Result} object, using the setting `:capture`. This works only for the `:out` and `:err` streams. * **Use the controller:** You may hook a stream to the controller using the setting `:controller`. You can then manipulate the stream via the controller. If you pass a block to {Toys::StandardMixins::Exec#exec}, it yields the {Toys::Utils::Exec::Controller}, giving you access to streams.
### Result handling
A subprocess result is represented by a {Toys::Utils::Exec::Result} object, which includes the exit code, the content of any captured output streams, and any exeption raised when attempting to run the process. When you run a process in the foreground, the method will return a result object. When you run a process in the background, you can obtain the result from the controller once the process completes.
The following example demonstrates running a process in the foreground and getting the exit code:
result = exec(["git", "init"]) puts "exit code: #{result.exit_code}"
The following example demonstrates starting a process in the background, waiting for it to complete, and getting its exit code:
controller = exec(["git", "init"], background: true) result = controller.result(timeout: 1.0) if result puts "exit code: #{result.exit_code}" else puts "timed out" end
You can also provide a callback that is executed once a process completes. This callback can be specified as a method name or a `Proc` object, and will be passed the result object. For example:
def run exec(["git", "init"], result_callback: :handle_result) end def handle_result(result) puts "exit code: #{result.exit_code}" end
Finally, you can force your tool to exit if a subprocess fails, similar to setting the `set -e` option in bash, by setting the `:exit_on_nonzero_status` option. This is often set as a default configuration for all subprocesses run in a tool, by passing it as an argument to the `include` directive:
include :exec, exit_on_nonzero_status: true
### Configuration Options
A variety of options can be used to control subprocesses. These can be provided to any method that starts a subprocess. You can also set defaults by passing them as keyword arguments when you `include` the mixin.
Options that affect the behavior of subprocesses:
* `:env` (Hash) Environment variables to pass to the subprocess. Keys represent variable names and should be strings. Values should be either strings or `nil`, which unsets the variable. * `:background` (Boolean) Runs the process in the background if `true`.
Options related to handling results
* `:result_callback` (Proc,Symbol) A procedure that is called, and passed the result object, when the subprocess exits. You can provide a `Proc` object, or the name of a method as a `Symbol`. * `:exit_on_nonzero_status` (Boolean) If set to true, a nonzero exit code will cause the tool to exit immediately with that same code. * `:e` (Boolean) A short name for `:exit_on_nonzero_status`.
Options for connecting input and output streams. See the section above on stream handling for info on the values that can be passed.
* `:in` Connects the input stream of the subprocess. See the section on stream handling. * `:out` Connects the standard output stream of the subprocess. See the section on stream handling. * `:err` Connects the standard error stream of the subprocess. See the section on stream handling.
Options related to logging and reporting:
* `:logger` (Logger) Logger to use for logging the actual command. If not present, the command is not logged. * `:log_level` (Integer,false) Level for logging the actual command. Defaults to Logger::INFO if not present. You may also pass `false` to disable logging of the command. * `:log_cmd` (String) The string logged for the actual command. Defaults to the `inspect` representation of the command. * `:name` (Object) An optional object that can be used to identify this subprocess. It is available in the controller and result objects.
In addition, the following options recognized by [`Process#spawn`](ruby-doc.org/core/Process.html#method-c-spawn) are supported.
* `:chdir` (String) Set the working directory for the command. * `:close_others` (Boolean) Whether to close non-redirected non-standard file descriptors. * `:new_pgroup` (Boolean) Create new process group (Windows only). * `:pgroup` (Integer,true,nil) The process group setting. * `:umask` (Integer) Umask setting for the new process. * `:unsetenv_others` (Boolean) Clear environment variables except those explicitly set.
Any other option key will result in an `ArgumentError`.
Constants
- KEY
Context
key for the executor object. @return [Object]
Public Class Methods
@private
# File lib/toys/standard_mixins/exec.rb, line 708 def self._interpret_e(value, context) return nil unless value proc do |result| if result.failed? context.exit(127) elsif result.signaled? context.exit(result.signal_code + 128) elsif result.error? context.exit(result.exit_code) end end end
@private
# File lib/toys/standard_mixins/exec.rb, line 722 def self._interpret_result_callback(value, context) if value.is_a?(::Symbol) context.method(value) elsif value.respond_to?(:call) proc { |r| context.instance_eval { value.call(r, context) } } elsif value.nil? nil else raise ::ArgumentError, "Bad value for result_callback" end end
@private
# File lib/toys/standard_mixins/exec.rb, line 679 def self._make_tool_caller(cmd) cmd = ::Shellwords.split(cmd) if cmd.is_a?(::String) proc { |config| ::Kernel.exit(config[:cli].run(*cmd)) } end
@private
# File lib/toys/standard_mixins/exec.rb, line 735 def self._setup_clean_process(cmd) raise ::ArgumentError, "Toys process is unknown" unless ::Toys.executable_path cmd = ::Shellwords.split(cmd) if cmd.is_a?(::String) cmd = [::RbConfig.ruby, "--disable=gems", ::Toys.executable_path] + cmd if defined?(::Bundler) if ::Bundler.respond_to?(:with_unbundled_env) ::Bundler.with_unbundled_env { yield(cmd) } else ::Bundler.with_clean_env { yield(cmd) } end else yield(cmd) end end
@private
# File lib/toys/standard_mixins/exec.rb, line 685 def self._setup_exec_opts(opts, context) count = 0 result_callback = nil if opts.key?(:result_callback) result_callback = _interpret_result_callback(opts[:result_callback], context) count += 1 end [:exit_on_nonzero_status, :e].each do |sym| if opts.key?(sym) result_callback = _interpret_e(opts[sym], context) count += 1 opts = opts.reject { |k, _v| k == sym } end end if count > 1 raise ::ArgumentError, "You can provide at most one of: result_callback, exit_on_nonzero_status, e" end opts = opts.merge(result_callback: result_callback) if count == 1 opts end
Public Instance Methods
Execute a command. The command may be given as a single string to pass to a shell, or an array of strings indicating a posix command.
Captures standard out and returns it as a string. Cannot be run in the background.
If a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
### Example
Capture the output of an echo command
str = capture(["echo", "hello"]) assert_equal("hello\n", str)
@param cmd [String,Array<String>] The command to execute. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [String] What was written to standard out.
# File lib/toys/standard_mixins/exec.rb, line 477 def capture(cmd, **opts, &block) opts = Exec._setup_exec_opts(opts, self) self[KEY].capture(cmd, **opts, &block) end
Execute a proc in a forked subprocess.
Captures standard out and returns it as a string. Cannot be run in the background.
If a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
Beware that some Ruby environments (e.g. JRuby, and Ruby on Windows) do not support this method because they do not support fork.
### Example
Run a proc in a forked process and capture its output:
code = proc do puts Process.pid end forked_pid = capture_proc(code).chomp puts "I forked PID #{forked_pid}"
@param func [Proc] The proc to call. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [String] What was written to standard out.
# File lib/toys/standard_mixins/exec.rb, line 545 def capture_proc(func, **opts, &block) opts = Exec._setup_exec_opts(opts, self) self[KEY].capture_proc(func, **opts, &block) end
Spawn a ruby process and pass the given arguments to it.
Captures standard out and returns it as a string. Cannot be run in the background.
If a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
### Example
Capture the output of a ruby script.
str = capture_ruby("-e", "(1..3).each { |i| puts i }") assert_equal "1\n2\n3\n", str
@param args [String,Array<String>] The arguments to ruby. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [String] What was written to standard out.
# File lib/toys/standard_mixins/exec.rb, line 508 def capture_ruby(args, **opts, &block) opts = Exec._setup_exec_opts(opts, self) self[KEY].capture_ruby(args, **opts, &block) end
Execute a tool in a separately spawned process.
Captures standard out and returns it as a string. Cannot be run in the background.
The command may be given as a single string or an array of strings, representing the tool to run and the arguments to pass.
If a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
An entirely separate spawned process is run for this tool, using the setting of {Toys.executable_path}. Thus, this method can be run only if that setting is present. The normal Toys
gem does set it, but if you are writing your own executable using Toys-Core, you will need to set it explicitly for this method to work. Furthermore, Bundler
, if present, is reset to its “unbundled” environment. Thus, the tool found, the behavior of the CLI
, and the gem environment, might not be the same as those of the calling tool.
This method is often used if you are already in a bundle and need to run a tool that uses a different bundle. It may also be necessary on environments without “fork” (such as JRuby or Ruby on Windows).
### Example
Run the “system version” tool and capture its output.
str = capture_separate_tool(["system", "version"]).chomp puts "Version was #{str}"
@param cmd [String,Array<String>] The tool to execute. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [String] What was written to standard out.
# File lib/toys/standard_mixins/exec.rb, line 630 def capture_separate_tool(cmd, **opts, &block) Exec._setup_clean_process(cmd) do |clean_cmd| capture(clean_cmd, **opts, &block) end end
Execute a tool in the current CLI
in a forked process.
Captures standard out and returns it as a string. Cannot be run in the background.
The command may be given as a single string or an array of strings, representing the tool to run and the arguments to pass.
If a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
Beware that some Ruby environments (e.g. JRuby, and Ruby on Windows) do not support this method because they do not support fork.
### Example
Run the “system version” tool and capture its output.
str = capture_tool(["system", "version"]).chomp puts "Version was #{str}"
@param cmd [String,Array<String>] The tool to execute. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [String] What was written to standard out.
# File lib/toys/standard_mixins/exec.rb, line 582 def capture_tool(cmd, **opts, &block) func = Exec._make_tool_caller(cmd) opts = Exec._setup_exec_opts(opts, self) self[KEY].capture_proc(func, **opts, &block) end
Set default configuration options.
See the {Toys::StandardMixins::Exec} module documentation for a description of the options.
@param opts [keywords] The default options. @return [self]
# File lib/toys/standard_mixins/exec.rb, line 255 def configure_exec(**opts) opts = Exec._setup_exec_opts(opts, self) self[KEY].configure_defaults(**opts) self end
Execute a command. The command may be given as a single string to pass to a shell, or an array of strings indicating a posix command.
If the process is not set to run in the background, and a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
### Examples
Run a command without a shell, and print the exit code (0 for success):
result = exec(["git", "init"]) puts "exit code: #{result.exit_code}"
Run a shell command:
result = exec("cd mydir && git init") puts "exit code: #{result.exit_code}"
@param cmd [String,Array<String>] The command to execute. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [Toys::Utils::Exec::Controller] The subprocess controller, if
the process is running in the background.
@return [Toys::Utils::Exec::Result] The result, if the process ran in
the foreground.
# File lib/toys/standard_mixins/exec.rb, line 293 def exec(cmd, **opts, &block) opts = Exec._setup_exec_opts(opts, self) self[KEY].exec(cmd, **opts, &block) end
Execute a proc in a forked subprocess.
If the process is not set to run in the background, and a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
Beware that some Ruby environments (e.g. JRuby, and Ruby on Windows) do not support this method because they do not support fork.
### Example
Run a proc in a forked process.
code = proc do puts "Spawned process ID is #{Process.pid}" end puts "Main process ID is #{Process.pid}" exec_proc(code)
@param func [Proc] The proc to call. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [Toys::Utils::Exec::Controller] The subprocess controller, if
the process is running in the background.
@return [Toys::Utils::Exec::Result] The result, if the process ran in
the foreground.
# File lib/toys/standard_mixins/exec.rb, line 361 def exec_proc(func, **opts, &block) opts = Exec._setup_exec_opts(opts, self) self[KEY].exec_proc(func, **opts, &block) end
Spawn a ruby process and pass the given arguments to it.
If the process is not set to run in the background, and a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
### Example
Execute a small script with warnings
exec_ruby("-w", "-e", "(1..10).each { |i| puts i }")
@param args [String,Array<String>] The arguments to ruby. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [Toys::Utils::Exec::Controller] The subprocess controller, if
the process is running in the background.
@return [Toys::Utils::Exec::Result] The result, if the process ran in
the foreground.
# File lib/toys/standard_mixins/exec.rb, line 323 def exec_ruby(args, **opts, &block) opts = Exec._setup_exec_opts(opts, self) self[KEY].exec_ruby(args, **opts, &block) end
Execute a tool in a separately spawned process.
The command may be given as a single string or an array of strings, representing the tool to run and the arguments to pass.
If the process is not set to run in the background, and a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
An entirely separate spawned process is run for this tool, using the setting of {Toys.executable_path}. Thus, this method can be run only if that setting is present. The normal Toys
gem does set it, but if you are writing your own executable using Toys-Core, you will need to set it explicitly for this method to work. Furthermore, Bundler
, if present, is reset to its “unbundled” environment. Thus, the tool found, the behavior of the CLI
, and the gem environment, might not be the same as those of the calling tool.
This method is often used if you are already in a bundle and need to run a tool that uses a different bundle. It may also be necessary on environments without “fork” (such as JRuby or Ruby on Windows).
### Example
Run the “system update” tool and pass it an argument.
exec_separate_tool(["system", "update", "--verbose"])
@param cmd [String,Array<String>] The tool to execute. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [Toys::Utils::Exec::Controller] The subprocess controller, if
the process is running in the background.
@return [Toys::Utils::Exec::Result] The result, if the process ran in
the foreground.
# File lib/toys/standard_mixins/exec.rb, line 444 def exec_separate_tool(cmd, **opts, &block) Exec._setup_clean_process(cmd) do |clean_cmd| exec(clean_cmd, **opts, &block) end end
Execute a tool in the current CLI
in a forked process.
The command may be given as a single string or an array of strings, representing the tool to run and the arguments to pass.
If the process is not set to run in the background, and a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
Beware that some Ruby environments (e.g. JRuby, and Ruby on Windows) do not support this method because they do not support fork.
### Example
Run the “system update” tool and pass it an argument.
exec_tool(["system", "update", "--verbose"])
@param cmd [String,Array<String>] The tool to execute. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [Toys::Utils::Exec::Controller] The subprocess controller, if
the process is running in the background.
@return [Toys::Utils::Exec::Result] The result, if the process ran in
the foreground.
# File lib/toys/standard_mixins/exec.rb, line 397 def exec_tool(cmd, **opts, &block) func = Exec._make_tool_caller(cmd) opts = Exec._setup_exec_opts(opts, self) self[KEY].exec_proc(func, **opts, &block) end
Exit if the given status code is nonzero. Otherwise, returns 0.
@param status [Integer,Process::Status,Toys::Utils::Exec::Result] @return [Integer]
# File lib/toys/standard_mixins/exec.rb, line 671 def exit_on_nonzero_status(status) status = status.exit_code if status.respond_to?(:exit_code) status = status.exitstatus if status.respond_to?(:exitstatus) Context.exit(status) unless status.zero? 0 end
Execute the given string in a shell. Returns the exit code. Cannot be run in the background.
If a block is provided, a {Toys::Utils::Exec::Controller} will be yielded to it.
### Example
Run a shell script
exit_code = sh("cd mydir && git init") puts exit_code == 0 ? "Success!" : "Failed!"
@param cmd [String] The shell command to execute. @param opts [keywords] The command options. See the section on
Configuration Options in the {Toys::StandardMixins::Exec} module documentation.
@yieldparam controller [Toys::Utils::Exec::Controller] A controller for
the subprocess. See the section on Controlling Processes in the {Toys::StandardMixins::Exec} module documentation.
@return [Integer] The exit code
# File lib/toys/standard_mixins/exec.rb, line 660 def sh(cmd, **opts, &block) opts = Exec._setup_exec_opts(opts, self) self[KEY].sh(cmd, **opts, &block) end