; set IDL_PATH
idl_path_filename = '~/.idl_path'
nPathDirs = file_lines(idl_path_filename)
pathDirs = strarr(nPathDirs)

openr, lun, idl_path_filename, /get_lun
readf, lun, pathDirs
free_lun, lun

commentPos = strpos(pathDirs, ';')
pathDirInds = where(commentPos ne 0, nPathDirs)
if (nPathDirs gt 0) then mg_set_path, pathDirs[pathDirInds]