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7. Optional Operating System Services

The modules described in this chapter provide interfaces to operating system features that are available on selected operating systems only. The interfaces are generally modelled after the Unix or C interfaces but they are available on some other systems as well (e.g. Windows or NT). Here's an overview:

`signal` | Set handlers for asynchronous events.
`socket` | Low-level networking interface.
`select` | Wait for I/O completion on multiple streams.
`thread` | Create multiple threads of control within one interpreter.
`threading` | Higher-level threading interface.
`Queue` | A synchronized queue class.
`anydbm` | Generic interface to DBM-style database modules.
`dumbdbm` | Portable implementation of the simple DBM interface.
`whichdb` | Guess which DBM-style module created a given database.
`zlib` | Low-level interface to compression and decompression routines compatible with \programgzip.
`gzip` | Interfaces for \programgzip compression and decompression using file objects.