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8. 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:

`posix` | The most common POSIX system calls (normally used via module `os`).
`pwd` | The password database (`getpwnam()` and friends).
`grp` | The group database (`getgrnam()` and friends).
`crypt` | The `crypt()` function used to check Unix passwords.
`dbm` | The standard ``database'' interface, based on ndbm.
`gdbm` | GNU's reinterpretation of dbm.
`termios` | POSIX style tty control.
`TERMIOS` | Symbolic constants required to use the `termios` module.
`fcntl` | The `fcntl()` and `ioctl()` system calls.
`posixfile` | A file-like object with support for locking.
`resource` | An interface to provide resource usage information on the current process.
`syslog` | An interface to the Unix syslog library routines.
`popen2` | Subprocesses with accessible standard I/O streams.
`commands` | Utility functions for running external commands.