class Shell

Parent:: Object
Included modules:: Shell::Error

Shell implements an idiomatic Ruby interface for common UNIX shell commands.

It provides users the ability to execute commands with filters and pipes, like sh/csh by using native facilities of Ruby.

Examples

Temp file creation

In this example we will create three tmpFile's in three different folders under the /tmp directory.

sh = Shell.cd("/tmp") # Change to the /tmp directory
sh.mkdir "shell-test-1" unless sh.exists?("shell-test-1")
# make the 'shell-test-1' directory if it doesn't already exist
sh.cd("shell-test-1") # Change to the /tmp/shell-test-1 directory
for dir in ["dir1", "dir3", "dir5"]
  if !sh.exists?(dir)
    sh.mkdir dir # make dir if it doesn't already exist
    sh.cd(dir) do
      # change to the `dir` directory
      f = sh.open("tmpFile", "w") # open a new file in write mode
      f.print "TEST\n"            # write to the file
      f.close                     # close the file handler
    end
    print sh.pwd                  # output the process working directory
  end
end

Temp file creation with self

This example is identical to the first, except we're using Shell::CommandProcessor#transact.

Shell::CommandProcessor#transact executes the given block against self, in this case sh; our Shell object. Within the block we can substitute sh.cd to cd, because the scope within the block uses sh already.

sh = Shell.cd("/tmp")
sh.transact do
  mkdir "shell-test-1" unless exists?("shell-test-1")
  cd("shell-test-1")
  for dir in ["dir1", "dir3", "dir5"]
    if !exists?(dir)
      mkdir dir
      cd(dir) do
        f = open("tmpFile", "w")
        f.print "TEST\n"
        f.close
      end
      print pwd
    end
  end
end

Pipe /etc/printcap into a file

In this example we will read the operating system file /etc/printcap, generated by cupsd, and then output it to a new file relative to the pwd of sh.

sh = Shell.new
sh.cat("/etc/printcap") | sh.tee("tee1") > "tee2"
(sh.cat < "/etc/printcap") | sh.tee("tee11") > "tee12"
sh.cat("/etc/printcap") | sh.tee("tee1") >> "tee2"
(sh.cat < "/etc/printcap") | sh.tee("tee11") >> "tee12"

Attributes

cascade[RW]

debug[RW]

debug?[RW]

verbose[RW]

verbose?[RW]

command_processor[R]

cwd[R]

Returns the current working directory.

debug[RW]

debug?[RW]

dir[R]

Returns the current working directory.

dir_stack[R]

dirs[R]

getwd[R]

Returns the current working directory.

process_controller[R]

pwd[R]

Returns the current working directory.

record_separator[RW]

system_path[R]

Returns the command search path in an array

umask[RW]

Returns the umask

verbose[RW]

verbose?[RW]

Public Class Methods

alias_command(alias, command, *opts, &block) Show source

# File lib/shell.rb, line 391
def Shell.alias_command(ali, command, *opts, &block)
  CommandProcessor.alias_command(ali, command, *opts, &block)
end

Convenience method for Shell::CommandProcessor.alias_command. Defines an instance method which will execute a command under an alternative name.

Shell.def_system_command('date')
Shell.alias_command('date_in_utc', 'date', '-u')
Shell.new.date_in_utc # => Sat Jan 25 16:59:57 UTC 2014

cd(path) Show source

# File lib/shell.rb, line 124
def cd(path)
  new(path)
end

Creates a new Shell instance with the current working directory set to path.

debug=(val) Show source

# File lib/shell.rb, line 113
def debug=(val)
  @debug = val
  @verbose = val if val
end

def_system_command(command, path = command) Show source

# File lib/shell.rb, line 371
def Shell.def_system_command(command, path = command)
  CommandProcessor.def_system_command(command, path)
end

Convenience method for Shell::CommandProcessor.def_system_command. Defines an instance method which will execute the given shell command. If the executable is not in ::default_system_path, you must supply the path to it.

Shell.def_system_command('hostname')
Shell.new.hostname # => localhost

# How to use an executable that's not in the default path

Shell.def_system_command('run_my_program', "~/hello")
Shell.new.run_my_program # prints "Hello from a C program!"

default_record_separator() Show source

# File lib/shell.rb, line 157
def default_record_separator
  if @default_record_separator
    @default_record_separator
  else
    $/
  end
end

default_record_separator=(rs) Show source

# File lib/shell.rb, line 165
def default_record_separator=(rs)
  @default_record_separator = rs
end

default_system_path() Show source

# File lib/shell.rb, line 141
def default_system_path
  if @default_system_path
    @default_system_path
  else
    ENV["PATH"].split(":")
  end
end

Returns the directories in the current shell's PATH environment variable as an array of directory names. This sets the #system_path for all instances of Shell.

Example: If in your current shell, you did:

$ echo $PATH
/usr/bin:/bin:/usr/local/bin

Running this method in the above shell would then return:

["/usr/bin", "/bin", "/usr/local/bin"]

default_system_path=(path) Show source

# File lib/shell.rb, line 153
def default_system_path=(path)
  @default_system_path = path
end

Sets the #system_path that new instances of Shell should have as their initial system_path.

path should be an array of directory name strings.

install_system_commands(pre = "sys_") Show source

# File lib/shell.rb, line 411
def Shell.install_system_commands(pre = "sys_")
  CommandProcessor.install_system_commands(pre)
end

Convenience method for Shell::CommandProcessor.install_system_commands. Defines instance methods representing all the executable files found in ::default_system_path, with the given prefix prepended to their names.

Shell.install_system_commands
Shell.new.sys_echo("hello") # => hello

new(pwd, umask) → obj Show source

# File lib/shell.rb, line 182
def initialize(pwd = Dir.pwd, umask = nil)
  @cwd = File.expand_path(pwd)
  @dir_stack = []
  @umask = umask

  @system_path = Shell.default_system_path
  @record_separator = Shell.default_record_separator

  @command_processor = CommandProcessor.new(self)
  @process_controller = ProcessController.new(self)

  @verbose = Shell.verbose
  @debug = Shell.debug
end

Creates a Shell object which current directory is set to the process current directory, unless otherwise specified by the pwd argument.

notify(*opts) { |mes| ... } Show source

# File lib/shell.rb, line 424
def self.notify(*opts)
  Shell::debug_output_synchronize do
    if opts[-1].kind_of?(String)
      yorn = verbose?
    else
      yorn = opts.pop
    end
    return unless yorn

    if @debug_display_thread_id
      if @debug_display_process_id
        prefix = "shell(##{Process.pid}:#{Thread.current.to_s.sub("Thread", "Th")}): "
      else
        prefix = "shell(#{Thread.current.to_s.sub("Thread", "Th")}): "
      end
    else
      prefix = "shell: "
    end
    _head = true
    STDERR.print opts.collect{|mes|
      mes = mes.dup
      yield mes if iterator?
      if _head
        _head = false
        prefix + mes
      else
        " "* prefix.size + mes
      end
    }.join("\n")+"\n"
  end
end

unalias_command(ali) Show source

# File lib/shell.rb, line 396
def Shell.unalias_command(ali)
  CommandProcessor.unalias_command(ali)
end

Convenience method for Shell::CommandProcessor.unalias_command

undef_system_command(command) Show source

# File lib/shell.rb, line 376
def Shell.undef_system_command(command)
  CommandProcessor.undef_system_command(command)
end

Convenience method for Shell::CommandProcessor.undef_system_command

Public Instance Methods

cd(path = nil, verbose = @verbose)

Alias for: chdir

chdir(path) Show source

# File lib/shell.rb, line 259
def chdir(path = nil, verbose = @verbose)
  check_point

  if iterator?
    notify("chdir(with block) #{path}") if verbose
    cwd_old = @cwd
    begin
      chdir(path, nil)
      yield
    ensure
      chdir(cwd_old, nil)
    end
  else
    notify("chdir #{path}") if verbose
    path = "~" unless path
    @cwd = expand_path(path)
    notify "current dir: #{@cwd}"
    rehash
    Void.new(self)
  end
end

Creates a Shell object which current directory is set to path.

If a block is given, it restores the current directory when the block ends.

If called as iterator, it restores the current directory when the block ends.

Also aliased as: cd

debug=(val) Show source

# File lib/shell.rb, line 214
def debug=(val)
  @debug = val
  @verbose = val if val
end

expand_path(path) Show source

# File lib/shell.rb, line 225
def expand_path(path)
  File.expand_path(path, @cwd)
end

inspect() Show source

# File lib/shell.rb, line 416
def inspect
  if debug.kind_of?(Integer) && debug > 2
    super
  else
    to_s
  end
end

Calls superclass method Object#inspect

jobs() Show source

# File lib/shell.rb, line 343
def jobs
  @process_controller.jobs
end

Returns a list of scheduled jobs.

kill(signal, job) Show source

# File lib/shell.rb, line 351
def kill(sig, command)
  @process_controller.kill_job(sig, command)
end

Sends the given signal to the given job

popd()

Alias for: popdir

popdir() Show source

# File lib/shell.rb, line 327
def popdir
  check_point

  notify("popdir")
  if pop = @dir_stack.pop
    chdir pop
    notify "dir stack: [#{@dir_stack.join ', '}]"
    self
  else
    Shell.Fail DirStackEmpty
  end
  Void.new(self)
end

Pops a directory from the directory stack, and sets the current directory to it.

Also aliased as: popd

pushd(path = nil, verbose = @verbose)

Alias for: pushdir

pushdir(path) Show source

pushdir(path) { &block }

# File lib/shell.rb, line 293
def pushdir(path = nil, verbose = @verbose)
  check_point

  if iterator?
    notify("pushdir(with block) #{path}") if verbose
    pushdir(path, nil)
    begin
      yield
    ensure
      popdir
    end
  elsif path
    notify("pushdir #{path}") if verbose
    @dir_stack.push @cwd
    chdir(path, nil)
    notify "dir stack: [#{@dir_stack.join ', '}]"
    self
  else
    notify("pushdir") if verbose
    if pop = @dir_stack.pop
      @dir_stack.push @cwd
      chdir pop
      notify "dir stack: [#{@dir_stack.join ', '}]"
      self
    else
      Shell.Fail DirStackEmpty
    end
  end
  Void.new(self)
end

Pushes the current directory to the directory stack, changing the current directory to path.

If path is omitted, it exchanges its current directory and the top of its directory stack.

If a block is given, it restores the current directory when the block ends.

Also aliased as: pushd

system_path=(path) Show source

# File lib/shell.rb, line 203
def system_path=(path)
  @system_path = path
  rehash
end

Sets the system path (the Shell instance's PATH environment variable).

path should be an array of directory name strings.

Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.