Module: Command

Defined in:
lib/local/command.rb

Defined Under Namespace

Classes: Error, Pipe

Class Method Summary collapse

Class Method Details

.command(cmd, stdin: nil, stderr: nil, fail: true) ⇒ Object

Execute the shell command ‘cmd’ and return standard-output as an array of strings. If :stdin is a string or an array of lines if will be fed to the command on standard-input, if it is a IO object that IO object is piped to the command

By default #command pass through standard-error but if :stderr is true, #command will return a tuple of standard-output, standard-error lines. If :stderr is false, standard-error is ignored and is the same as adding “2>/dev/null” to the command

#command raises a Command::Error exception if the command return with an exit code != 0 unless :fail is false. In that case the the exit code can be fetched from Command::status



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# File 'lib/local/command.rb', line 109

def command(cmd, stdin: nil, stderr: nil, fail: true)
  cmd = "set -o errexit\nset -o pipefail\n#{cmd}"

  pw = IO::pipe # pipe[0] for read, pipe[1] for write
  pr = IO::pipe
  pe = IO::pipe

  STDOUT.flush

  pid = fork {
    pw[1].close
    pr[0].close
    pe[0].close

    STDIN.reopen(pw[0])
    pw[0].close

    STDOUT.reopen(pr[1])
    pr[1].close

    STDERR.reopen(pe[1])
    pe[1].close

    exec(cmd)
  }

  pw[0].close
  pr[1].close
  pe[1].close

  if stdin
    case stdin
      when IO; pw[1].write(stdin.read)
      when String; pw[1].write(stdin)
      when Array; pw[1].write(stdin.join("\n") + "\n")
    end
    pw[1].flush
    pw[1].close
  end

  @status = Process.waitpid2(pid)[1].exitstatus

  out = pr[0].readlines.map(&:chomp)
  err = pe[0].readlines.map(&:chomp)

  pw[1].close if !stdin
  pr[0].close
  pe[0].close

  if @status != 0
    @exception = Command::Error.new(cmd, @status, stdin, out, err)
    raise @exception if fail
  else
    @exception = nil
  end

  case stderr
    when true; [out, err]
    when false; out
    when nil
      $stderr.puts err
      out
  end
end

.command?(cmd, expect: 0, stdin: nil, stderr: false) ⇒ Boolean

Like command but returns true if the command exited with the expected status. Note that it suppresses standard-error by default

Returns:

  • (Boolean) 


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# File 'lib/local/command.rb', line 184

def command?(cmd, expect: 0, stdin: nil, stderr: false)
  command(cmd, stdin: stdin, stderr: stderr, fail: false)
  @status == expect
end

.exception ⇒ Object

Stored exception when #command is called with :fail true



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# File 'lib/local/command.rb', line 179

def exception() @exception end

.status ⇒ Object

Exit status of the last command. FIXME: This is not usable because the methods raise an exception if the command exited with anything but 0



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# File 'lib/local/command.rb', line 176

def status() @status end