module MiGA::Common::SystemCall

General functions for process (system call) execution

Public Instance Methods

run_cmd(cmd, opts = {}) click to toggle source

Execute the command cmd with options opts determined by run_cmd_opts

The command cmd can be:

String: The command is processed as is, without changes
Array: The command is built with shelljoin so each value is escaped

# File lib/miga/common/system_call.rb, line 12
def run_cmd(cmd, opts = {})
  opts = run_cmd_opts(opts)
  cmd = cmd.shelljoin if cmd.is_a?(Array)
  spawn_opts = {}
  spawn_opts[:out] = opts[:stdout] if opts[:stdout]
  spawn_opts[:err] = opts[:stderr] if opts[:stderr]
  out_io, spawn_opts[:out] = IO.pipe if opts[:return] == :output
  spawn_opts[:err] = [:child, :out] if opts[:err2out] && spawn_opts[:out]
  opts[:source] = MiGA::MiGA.rc_path if opts[:source] == :miga
  if opts[:source] && File.exist?(opts[:source])
    cmd = ". #{opts[:source].shellescape} && #{cmd}"
  end

  DEBUG "CMD: #{cmd}"
  puts "CMD: #{cmd}" if opts[:show_cmd]
  return if opts[:dry]

  pid = nil
  error = nil
  begin
    pid = spawn(opts[:env], cmd, spawn_opts)
    Process.wait(pid)
  rescue => e
    error = e
  end
  status = $?

  if opts[:raise] && !status&.success?
    raise MiGA::SystemCallError.new(
      "Command failed with status "            "#{status&.exitstatus}#{' (core dump)' if status&.coredump?}:\n"            "#{error&.class}: #{error&.message}\n"            "OPT: #{opts}\n"            "CMD: #{cmd}"
    )
  end

  case opts[:return]
  when :status ; status
  when :pid    ; pid
  when :error  ; error
  when :output
    spawn_opts[:out].close
    output = out_io.read
    out_io.close
    output
  end
end

run_cmd_opts(opts = {}) click to toggle source

Options for run_cmd using a Hash opts to modify defaults

Supported keys (as Symbol) include:

stdout: Redirect STDOUT to this file
stderr: Redirect STDOUT to this file
dry: Don't run, just send the command to debug (default: false)
return: What should the function return, supported values are :status (Process::Status, default), :pid (Integer, process ID), :error (Error if failed, nil otherwise), :output (String, contents sent to STDOUT)
raise: Raise an exception (MiGA::SystemCallError) in case of failure (default: true)
show_cmd: Print command to the STDOUT (prefixed with CMD: ) to ease debugging (default: false)
err2out: Redirect STDERR to STDOUT
env: Environmental variables as a Hash, keys and values must be strings
source: A file to be sourced before running, or the Symbol :miga to source the MiGA configuration file

# File lib/miga/common/system_call.rb, line 80
def run_cmd_opts(opts = {})
  {
    stdout: nil,
    stderr: nil,
    dry: false,
    return: :status,
    raise: true,
    show_cmd: false,
    err2out: false,
    env: {},
    source: nil
  }.merge(opts)
end