class Inspec::ShellDetector


the caller.
verified against a list of known shells before being returned to
Since none of these methods is fullproof, the detected shell is
- The shell returned by getpwuid for our process UID
- The SHELL environment variable
- The command of our parent
running by checking:
ShellDetector attempts to detect the shell the invoking user is

def detect 

def detect
  # Most of our detection code assumes a unix-like environment
  return nil if RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/
  shellpath = detect_by_ppid
  if shellpath.nil? || shellpath.empty? || !known_shell?(shellpath)
    shellpath = detect_by_env
  end
  if shellpath.nil? || shellpath.empty? || !known_shell?(shellpath)
    shellpath = detect_by_getpwuid
  end
  shellname(shellpath) if known_shell?(shellpath)
end

def detect_by_env 

def detect_by_env
  ENV['SHELL']
end

def detect_by_getpwuid 

def detect_by_getpwuid
  Etc.getpwuid(Process.uid).shell
end

def detect_by_ppid 

def detect_by_ppid
  ppid = Process.ppid
  if Dir.exist?('/proc')
    File.readlink("/proc/#{ppid}/exe")
  else
    `ps -cp #{ppid} -o command=`.chomp
  end
end

def detected?(arg) 

def detected?(arg)
  arg != NOT_DETECTED
end

def initialize 

def initialize
  @shell = NOT_DETECTED
end

def known_shell?(shell)


do anything very silly.
Only return shells that we know about, just to be sure we never
def known_shell?(shell)
  KNOWN_SHELLS.include?(shellname(shell))
end

def shell 

def shell
  @shell = detect if !detected?(@shell)
  @shell
end

def shell! 

def shell!
  @shell = detect
end

def shellname(shellpath)


Strip any leading path elements
def shellname(shellpath)
  shellpath.split('/').last
end