| \chapter{Unix Specific Services} | 
 |  | 
 | The modules described in this chapter provide interfaces to features | 
 | that are unique to the \UNIX{} operating system, or in some cases to | 
 | some or many variants of it.  Here's an overview: | 
 |  | 
 | \begin{description} | 
 |  | 
 | \item[posix] | 
 | --- The most common Posix system calls (normally used via module \code{os}). | 
 |  | 
 | \item[posixpath] | 
 | --- Common Posix pathname manipulations (normally used via \code{os.path}). | 
 |  | 
 | \item[pwd] | 
 | --- The password database (\code{getpwnam()} and friends). | 
 |  | 
 | \item[grp] | 
 | --- The group database (\code{getgrnam()} and friends). | 
 |  | 
 | \item[crypt] | 
 | --- The \code{crypt()} function used to check \UNIX{} passwords. | 
 |  | 
 | \item[dbm] | 
 | --- The standard ``database'' interface, based on \code{ndbm}. | 
 |  | 
 | \item[gdbm] | 
 | --- GNU's reinterpretation of dbm. | 
 |  | 
 | \item[termios] | 
 | --- Posix style tty control. | 
 |  | 
 | \item[TERMIOS] | 
 | --- The symbolic constants required to use the \code{termios} module. | 
 |  | 
 | \item[fcntl] | 
 | --- The \code{fcntl()} and \code{ioctl()} system calls. | 
 |  | 
 | \item[posixfile] | 
 | --- A file-like object with support for locking. | 
 |  | 
 | \item[resource] | 
 | --- An interface to provide resource usage information on the current | 
 | process. | 
 |  | 
 | \item[syslog] | 
 | --- An interface to the \UNIX{} \code{syslog} library routines. | 
 |  | 
 | \end{description} |