append / prepend / remove path from PATH

bashrc

addpath() { #{{{
local method path

if (($#==0));then
  cat <<_EOF_
addpath [+|_|-] path [... pathN]
  +  append path (default)
  -  remove path
  _  prepend path
_EOF_
  return
fi

case "$1" in
  '+')
	method=append
	shift
	;;
  '_')
	method=prepend
	shift
	;;
  '-')
	method=remove
	shift
	;;
esac
if [[ -z $method ]];then
  method=append
fi
if [[ $method == append ]] || [[ $method == prepend ]];then
  for path in "$@";do
	if [[ :$PATH: == *:$path:* ]];then
	  continue
	fi
	if [[ ! -d "$path" ]];then
	  continue
	fi
	if [[ $method == append ]];then
	  PATH=$PATH:$path
	else
	  PATH=$path:$PATH
	fi
  done
elif [[ $method == remove ]];then
  local _PATH=:${PATH//:/::}:
  for path in "$@";do
	if [[ $_PATH == *:$path:* ]];then
	  _PATH=${_PATH//:$path:/}
	fi
  done
  while true;do
	if [[ $_PATH == *::* ]];then
	  _PATH=${_PATH//::/:}
	else
	  break
	fi
  done
  _PATH=${_PATH#:}
  _PATH=${_PATH%:}
  PATH=$_PATH
fi
} #}}}