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NAME

       POSIX - Perl interface to IEEE Std 1003.1

SYNOPSIS

           use POSIX;
           use POSIX qw(setsid);
           use POSIX qw(:errno_h :fcntl_h);

           printf "EINTR is %d\n", EINTR;

           $sess_id = POSIX::setsid();

           $fd = POSIX::open($path, O_CREAT|O_EXCL|O_WRONLY, 0644);
               # note: that's a filedescriptor, *NOT* a filehandle

DESCRIPTION

       The POSIX module permits you to access all (or nearly all) the standard POSIX 1003.1
       identifiers.  Many of these identifiers have been given Perl-ish interfaces.

       Everything is exported by default with the exception of any POSIX functions with the same
       name as a built-in Perl function, such as "abs", "alarm", "rmdir", "write", etc.., which
       will be exported only if you ask for them explicitly.  This is an unfortunate backwards
       compatibility feature.  You can stop the exporting by saying "use POSIX ()" and then use
       the fully qualified names (ie. "POSIX::SEEK_END").

       This document gives a condensed list of the features available in the POSIX module.
       Consult your operating system's manpages for general information on most features.
       Consult perlfunc for functions which are noted as being identical to Perl's builtin
       functions.

       The first section describes POSIX functions from the 1003.1 specification.  The second
       section describes some classes for signal objects, TTY objects, and other miscellaneous
       objects.  The remaining sections list various constants and macros in an organization
       which roughly follows IEEE Std 1003.1b-1993.

NOTE

       The POSIX module is probably the most complex Perl module supplied with the standard
       distribution.  It incorporates autoloading, namespace games, and dynamic loading of code
       that's in Perl, C, or both.  It's a great source of wisdom.

CAVEATS

       A few functions are not implemented because they are C specific.  If you attempt to call
       these, they will print a message telling you that they aren't implemented, and suggest
       using the Perl equivalent should one exist.  For example, trying to access the setjmp()
       call will elicit the message "setjmp() is C-specific: use eval {} instead".

       Furthermore, some evil vendors will claim 1003.1 compliance, but in fact are not so: they
       will not pass the PCTS (POSIX Compliance Test Suites).  For example, one vendor may not
       define EDEADLK, or the semantics of the errno values set by open(2) might not be quite
       right.  Perl does not attempt to verify POSIX compliance.  That means you can currently
       successfully say "use POSIX",  and then later in your program you find that your vendor
       has been lax and there's no usable ICANON macro after all.  This could be construed to be
       a bug.

FUNCTIONS

       _exit   This is identical to the C function "_exit()".  It exits the program immediately
               which means among other things buffered I/O is not flushed.

               Note that when using threads and in Linux this is not a good way to exit a thread
               because in Linux processes and threads are kind of the same thing (Note: while
               this is the situation in early 2003 there are projects under way to have threads
               with more POSIXly semantics in Linux).  If you want not to return from a thread,
               detach the thread.

       abort   This is identical to the C function "abort()".  It terminates the process with a
               "SIGABRT" signal unless caught by a signal handler or if the handler does not
               return normally (it e.g.  does a "longjmp").

       abs     This is identical to Perl's builtin "abs()" function, returning the absolute value
               of its numerical argument.

       access  Determines the accessibility of a file.

                       if( POSIX::access( "/", &POSIX::R_OK ) ){
                               print "have read permission\n";
                       }

               Returns "undef" on failure.  Note: do not use "access()" for security purposes.
               Between the "access()" call and the operation you are preparing for the
               permissions might change: a classic race condition.

       acos    This is identical to the C function "acos()", returning the arcus cosine of its
               numerical argument.  See also Math::Trig.

       alarm   This is identical to Perl's builtin "alarm()" function, either for arming or
               disarming the "SIGARLM" timer.

       asctime This is identical to the C function "asctime()".  It returns a string of the form

                       "Fri Jun  2 18:22:13 2000\n\0"

               and it is called thusly

                       $asctime = asctime($sec, $min, $hour, $mday, $mon, $year,
                                          $wday, $yday, $isdst);

               The $mon is zero-based: January equals 0.  The $year is 1900-based: 2001 equals
               101.  $wday and $yday default to zero (and are usually ignored anyway), and $isdst
               defaults to -1.

       asin    This is identical to the C function "asin()", returning the arcus sine of its
               numerical argument.  See also Math::Trig.

       assert  Unimplemented, but you can use "die" in perlfunc and the Carp module to achieve
               similar things.

       atan    This is identical to the C function "atan()", returning the arcus tangent of its
               numerical argument.  See also Math::Trig.

       atan2   This is identical to Perl's builtin "atan2()" function, returning the arcus
               tangent defined by its two numerical arguments, the y coordinate and the x
               coordinate.  See also Math::Trig.

       atexit  atexit() is C-specific: use "END {}" instead, see perlsub.

       atof    atof() is C-specific.  Perl converts strings to numbers transparently.  If you
               need to force a scalar to a number, add a zero to it.

       atoi    atoi() is C-specific.  Perl converts strings to numbers transparently.  If you
               need to force a scalar to a number, add a zero to it.  If you need to have just
               the integer part, see "int" in perlfunc.

       atol    atol() is C-specific.  Perl converts strings to numbers transparently.  If you
               need to force a scalar to a number, add a zero to it.  If you need to have just
               the integer part, see "int" in perlfunc.

       bsearch bsearch() not supplied.  For doing binary search on wordlists, see Search::Dict.

       calloc  calloc() is C-specific.  Perl does memory management transparently.

       ceil    This is identical to the C function "ceil()", returning the smallest integer value
               greater than or equal to the given numerical argument.

       chdir   This is identical to Perl's builtin "chdir()" function, allowing one to change the
               working (default) directory, see "chdir" in perlfunc.

       chmod   This is identical to Perl's builtin "chmod()" function, allowing one to change
               file and directory permissions, see "chmod" in perlfunc.

       chown   This is identical to Perl's builtin "chown()" function, allowing one to change
               file and directory owners and groups, see "chown" in perlfunc.

       clearerr
               Use the method "IO::Handle::clearerr()" instead, to reset the error state (if any)
               and EOF state (if any) of the given stream.

       clock   This is identical to the C function "clock()", returning the amount of spent
               processor time in microseconds.

       close   Close the file.  This uses file descriptors such as those obtained by calling
               "POSIX::open".

                       $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
                       POSIX::close( $fd );

               Returns "undef" on failure.

               See also "close" in perlfunc.

       closedir
               This is identical to Perl's builtin "closedir()" function for closing a directory
               handle, see "closedir" in perlfunc.

       cos     This is identical to Perl's builtin "cos()" function, for returning the cosine of
               its numerical argument, see "cos" in perlfunc.  See also Math::Trig.

       cosh    This is identical to the C function "cosh()", for returning the hyperbolic cosine
               of its numeric argument.  See also Math::Trig.

       creat   Create a new file.  This returns a file descriptor like the ones returned by
               "POSIX::open".  Use "POSIX::close" to close the file.

                       $fd = POSIX::creat( "foo", 0611 );
                       POSIX::close( $fd );

               See also "sysopen" in perlfunc and its "O_CREAT" flag.

       ctermid Generates the path name for the controlling terminal.

                       $path = POSIX::ctermid();

       ctime   This is identical to the C function "ctime()" and equivalent to
               "asctime(localtime(...))", see "asctime" and "localtime".

       cuserid Get the login name of the owner of the current process.

                       $name = POSIX::cuserid();

       difftime
               This is identical to the C function "difftime()", for returning the time
               difference (in seconds) between two times (as returned by "time()"), see "time".

       div     div() is C-specific, use "int" in perlfunc on the usual "/" division and the
               modulus "%".

       dup     This is similar to the C function "dup()", for duplicating a file descriptor.

               This uses file descriptors such as those obtained by calling "POSIX::open".

               Returns "undef" on failure.

       dup2    This is similar to the C function "dup2()", for duplicating a file descriptor to
               an another known file descriptor.

               This uses file descriptors such as those obtained by calling "POSIX::open".

               Returns "undef" on failure.

       errno   Returns the value of errno.

                       $errno = POSIX::errno();

               This identical to the numerical values of the $!, see "$ERRNO" in perlvar.

       execl   execl() is C-specific, see "exec" in perlfunc.

       execle  execle() is C-specific, see "exec" in perlfunc.

       execlp  execlp() is C-specific, see "exec" in perlfunc.

       execv   execv() is C-specific, see "exec" in perlfunc.

       execve  execve() is C-specific, see "exec" in perlfunc.

       execvp  execvp() is C-specific, see "exec" in perlfunc.

       exit    This is identical to Perl's builtin "exit()" function for exiting the program, see
               "exit" in perlfunc.

       exp     This is identical to Perl's builtin "exp()" function for returning the exponent
               (e-based) of the numerical argument, see "exp" in perlfunc.

       fabs    This is identical to Perl's builtin "abs()" function for returning the absolute
               value of the numerical argument, see "abs" in perlfunc.

       fclose  Use method "IO::Handle::close()" instead, or see "close" in perlfunc.

       fcntl   This is identical to Perl's builtin "fcntl()" function, see "fcntl" in perlfunc.

       fdopen  Use method "IO::Handle::new_from_fd()" instead, or see "open" in perlfunc.

       feof    Use method "IO::Handle::eof()" instead, or see "eof" in perlfunc.

       ferror  Use method "IO::Handle::error()" instead.

       fflush  Use method "IO::Handle::flush()" instead.  See also "$OUTPUT_AUTOFLUSH" in
               perlvar.

       fgetc   Use method "IO::Handle::getc()" instead, or see "read" in perlfunc.

       fgetpos Use method "IO::Seekable::getpos()" instead, or see "seek" in L.

       fgets   Use method "IO::Handle::gets()" instead.  Similar to <>, also known as "readline"
               in perlfunc.

       fileno  Use method "IO::Handle::fileno()" instead, or see "fileno" in perlfunc.

       floor   This is identical to the C function "floor()", returning the largest integer value
               less than or equal to the numerical argument.

       fmod    This is identical to the C function "fmod()".

                       $r = fmod($x, $y);

               It returns the remainder "$r = $x - $n*$y", where "$n = trunc($x/$y)".  The $r has
               the same sign as $x and magnitude (absolute value) less than the magnitude of $y.

       fopen   Use method "IO::File::open()" instead, or see "open" in perlfunc.

       fork    This is identical to Perl's builtin "fork()" function for duplicating the current
               process, see "fork" in perlfunc and perlfork if you are in Windows.

       fpathconf
               Retrieves the value of a configurable limit on a file or directory.  This uses
               file descriptors such as those obtained by calling "POSIX::open".

               The following will determine the maximum length of the longest allowable pathname
               on the filesystem which holds "/var/foo".

                       $fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY );
                       $path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX );

               Returns "undef" on failure.

       fprintf fprintf() is C-specific, see "printf" in perlfunc instead.

       fputc   fputc() is C-specific, see "print" in perlfunc instead.

       fputs   fputs() is C-specific, see "print" in perlfunc instead.

       fread   fread() is C-specific, see "read" in perlfunc instead.

       free    free() is C-specific.  Perl does memory management transparently.

       freopen freopen() is C-specific, see "open" in perlfunc instead.

       frexp   Return the mantissa and exponent of a floating-point number.

                       ($mantissa, $exponent) = POSIX::frexp( 1.234e56 );

       fscanf  fscanf() is C-specific, use <> and regular expressions instead.

       fseek   Use method "IO::Seekable::seek()" instead, or see "seek" in perlfunc.

       fsetpos Use method "IO::Seekable::setpos()" instead, or seek "seek" in perlfunc.

       fstat   Get file status.  This uses file descriptors such as those obtained by calling
               "POSIX::open".  The data returned is identical to the data from Perl's builtin
               "stat" function.

                       $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
                       @stats = POSIX::fstat( $fd );

       fsync   Use method "IO::Handle::sync()" instead.

       ftell   Use method "IO::Seekable::tell()" instead, or see "tell" in perlfunc.

       fwrite  fwrite() is C-specific, see "print" in perlfunc instead.

       getc    This is identical to Perl's builtin "getc()" function, see "getc" in perlfunc.

       getchar Returns one character from STDIN.  Identical to Perl's "getc()", see "getc" in
               perlfunc.

       getcwd  Returns the name of the current working directory.  See also Cwd.

       getegid Returns the effective group identifier.  Similar to Perl' s builtin variable $(,
               see "$EGID" in perlvar.

       getenv  Returns the value of the specified environment variable.  The same information is
               available through the %ENV array.

       geteuid Returns the effective user identifier.  Identical to Perl's builtin $> variable,
               see "$EUID" in perlvar.

       getgid  Returns the user's real group identifier.  Similar to Perl's builtin variable $),
               see "$GID" in perlvar.

       getgrgid
               This is identical to Perl's builtin "getgrgid()" function for returning group
               entries by group identifiers, see "getgrgid" in perlfunc.

       getgrnam
               This is identical to Perl's builtin "getgrnam()" function for returning group
               entries by group names, see "getgrnam" in perlfunc.

       getgroups
               Returns the ids of the user's supplementary groups.  Similar to Perl's builtin
               variable $), see "$GID" in perlvar.

       getlogin
               This is identical to Perl's builtin "getlogin()" function for returning the user
               name associated with the current session, see "getlogin" in perlfunc.

       getpgrp This is identical to Perl's builtin "getpgrp()" function for returning the process
               group identifier of the current process, see "getpgrp" in perlfunc.

       getpid  Returns the process identifier.  Identical to Perl's builtin variable $$, see
               "$PID" in perlvar.

       getppid This is identical to Perl's builtin "getppid()" function for returning the process
               identifier of the parent process of the current process , see "getppid" in
               perlfunc.

       getpwnam
               This is identical to Perl's builtin "getpwnam()" function for returning user
               entries by user names, see "getpwnam" in perlfunc.

       getpwuid
               This is identical to Perl's builtin "getpwuid()" function for returning user
               entries by user identifiers, see "getpwuid" in perlfunc.

       gets    Returns one line from "STDIN", similar to <>, also known as the "readline()"
               function, see "readline" in perlfunc.

               NOTE: if you have C programs that still use "gets()", be very afraid.  The
               "gets()" function is a source of endless grief because it has no buffer overrun
               checks.  It should never be used.  The "fgets()" function should be preferred
               instead.

       getuid  Returns the user's identifier.  Identical to Perl's builtin $< variable, see
               "$UID" in perlvar.

       gmtime  This is identical to Perl's builtin "gmtime()" function for converting seconds
               since the epoch to a date in Greenwich Mean Time, see "gmtime" in perlfunc.

       isalnum This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "isalnum".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:alnum:]]/"
               construct instead, or possibly the "/\w/" construct.

       isalpha This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "isalpha".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:alpha:]]/"
               construct instead.

       isatty  Returns a boolean indicating whether the specified filehandle is connected to a
               tty.  Similar to the "-t" operator, see "-X" in perlfunc.

       iscntrl This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "iscntrl".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:cntrl:]]/"
               construct instead.

       isdigit This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "isdigit" (unlikely, but still possible). Does not work
               on Unicode characters code point 256 or higher.  Consider using regular
               expressions and the "/[[:digit:]]/" construct instead, or the "/\d/" construct.

       isgraph This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "isgraph".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:graph:]]/"
               construct instead.

       islower This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "islower".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:lower:]]/"
               construct instead.  Do not use "/[a-z]/".

       isprint This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "isprint".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:print:]]/"
               construct instead.

       ispunct This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "ispunct".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:punct:]]/"
               construct instead.

       isspace This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "isspace".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:space:]]/"
               construct instead, or the "/\s/" construct.  (Note that "/\s/" and "/[[:space:]]/"
               are slightly different in that "/[[:space:]]/" can normally match a vertical tab,
               while "/\s/" does not.)

       isupper This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "isupper".  Does not work on Unicode characters code
               point 256 or higher.  Consider using regular expressions and the "/[[:upper:]]/"
               construct instead.  Do not use "/[A-Z]/".

       isxdigit
               This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Note that locale settings may affect what
               characters are considered "isxdigit" (unlikely, but still possible).  Does not
               work on Unicode characters code point 256 or higher.  Consider using regular
               expressions and the "/[[:xdigit:]]/" construct instead, or simply "/[0-9a-f]/i".

       kill    This is identical to Perl's builtin "kill()" function for sending signals to
               processes (often to terminate them), see "kill" in perlfunc.

       labs    (For returning absolute values of long integers.)  labs() is C-specific, see "abs"
               in perlfunc instead.

       lchown  This is identical to the C function, except the order of arguments is consistent
               with Perl's builtin "chown()" with the added restriction of only one path, not an
               list of paths.  Does the same thing as the "chown()" function but changes the
               owner of a symbolic link instead of the file the symbolic link points to.

       ldexp   This is identical to the C function "ldexp()" for multiplying floating point
               numbers with powers of two.

                       $x_quadrupled = POSIX::ldexp($x, 2);

       ldiv    (For computing dividends of long integers.)  ldiv() is C-specific, use "/" and
               "int()" instead.

       link    This is identical to Perl's builtin "link()" function for creating hard links into
               files, see "link" in perlfunc.

       localeconv
               Get numeric formatting information.  Returns a reference to a hash containing the
               current locale formatting values.

               Here is how to query the database for the de (Deutsch or German) locale.

                       $loc = POSIX::setlocale( &POSIX::LC_ALL, "de" );
                       print "Locale = $loc\n";
                       $lconv = POSIX::localeconv();
                       print "decimal_point    = ", $lconv->{decimal_point},   "\n";
                       print "thousands_sep    = ", $lconv->{thousands_sep},   "\n";
                       print "grouping = ", $lconv->{grouping},        "\n";
                       print "int_curr_symbol  = ", $lconv->{int_curr_symbol}, "\n";
                       print "currency_symbol  = ", $lconv->{currency_symbol}, "\n";
                       print "mon_decimal_point = ", $lconv->{mon_decimal_point}, "\n";
                       print "mon_thousands_sep = ", $lconv->{mon_thousands_sep}, "\n";
                       print "mon_grouping     = ", $lconv->{mon_grouping},    "\n";
                       print "positive_sign    = ", $lconv->{positive_sign},   "\n";
                       print "negative_sign    = ", $lconv->{negative_sign},   "\n";
                       print "int_frac_digits  = ", $lconv->{int_frac_digits}, "\n";
                       print "frac_digits      = ", $lconv->{frac_digits},     "\n";
                       print "p_cs_precedes    = ", $lconv->{p_cs_precedes},   "\n";
                       print "p_sep_by_space   = ", $lconv->{p_sep_by_space},  "\n";
                       print "n_cs_precedes    = ", $lconv->{n_cs_precedes},   "\n";
                       print "n_sep_by_space   = ", $lconv->{n_sep_by_space},  "\n";
                       print "p_sign_posn      = ", $lconv->{p_sign_posn},     "\n";
                       print "n_sign_posn      = ", $lconv->{n_sign_posn},     "\n";

       localtime
               This is identical to Perl's builtin "localtime()" function for converting seconds
               since the epoch to a date see "localtime" in perlfunc.

       log     This is identical to Perl's builtin "log()" function, returning the natural
               (e-based) logarithm of the numerical argument, see "log" in perlfunc.

       log10   This is identical to the C function "log10()", returning the 10-base logarithm of
               the numerical argument.  You can also use

                   sub log10 { log($_[0]) / log(10) }

               or

                   sub log10 { log($_[0]) / 2.30258509299405 }

               or

                   sub log10 { log($_[0]) * 0.434294481903252 }

       longjmp longjmp() is C-specific: use "die" in perlfunc instead.

       lseek   Move the file's read/write position.  This uses file descriptors such as those
               obtained by calling "POSIX::open".

                       $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
                       $off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET );

               Returns "undef" on failure.

       malloc  malloc() is C-specific.  Perl does memory management transparently.

       mblen   This is identical to the C function "mblen()".  Perl does not have any support for
               the wide and multibyte characters of the C standards, so this might be a rather
               useless function.

       mbstowcs
               This is identical to the C function "mbstowcs()".  Perl does not have any support
               for the wide and multibyte characters of the C standards, so this might be a
               rather useless function.

       mbtowc  This is identical to the C function "mbtowc()".  Perl does not have any support
               for the wide and multibyte characters of the C standards, so this might be a
               rather useless function.

       memchr  memchr() is C-specific, see "index" in perlfunc instead.

       memcmp  memcmp() is C-specific, use "eq" instead, see perlop.

       memcpy  memcpy() is C-specific, use "=", see perlop, or see "substr" in perlfunc.

       memmove memmove() is C-specific, use "=", see perlop, or see "substr" in perlfunc.

       memset  memset() is C-specific, use "x" instead, see perlop.

       mkdir   This is identical to Perl's builtin "mkdir()" function for creating directories,
               see "mkdir" in perlfunc.

       mkfifo  This is similar to the C function "mkfifo()" for creating FIFO special files.

                       if (mkfifo($path, $mode)) { ....

               Returns "undef" on failure.  The $mode is similar to the mode of "mkdir()", see
               "mkdir" in perlfunc, though for "mkfifo" you must specify the $mode.

       mktime  Convert date/time info to a calendar time.

               Synopsis:

                       mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = -1)

               The month ("mon"), weekday ("wday"), and yearday ("yday") begin at zero.  I.e.
               January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1.  The year
               ("year") is given in years since 1900.  I.e. The year 1995 is 95; the year 2001 is
               101.  Consult your system's "mktime()" manpage for details about these and the
               other arguments.

               Calendar time for December 12, 1995, at 10:30 am.

                       $time_t = POSIX::mktime( 0, 30, 10, 12, 11, 95 );
                       print "Date = ", POSIX::ctime($time_t);

               Returns "undef" on failure.

       modf    Return the integral and fractional parts of a floating-point number.

                       ($fractional, $integral) = POSIX::modf( 3.14 );

       nice    This is similar to the C function "nice()", for changing the scheduling preference
               of the current process.  Positive arguments mean more polite process, negative
               values more needy process.  Normal user processes can only be more polite.

               Returns "undef" on failure.

       offsetof
               offsetof() is C-specific, you probably want to see "pack" in perlfunc instead.

       open    Open a file for reading for writing.  This returns file descriptors, not Perl
               filehandles.  Use "POSIX::close" to close the file.

               Open a file read-only with mode 0666.

                       $fd = POSIX::open( "foo" );

               Open a file for read and write.

                       $fd = POSIX::open( "foo", &POSIX::O_RDWR );

               Open a file for write, with truncation.

                       $fd = POSIX::open( "foo", &POSIX::O_WRONLY | &POSIX::O_TRUNC );

               Create a new file with mode 0640.  Set up the file for writing.

                       $fd = POSIX::open( "foo", &POSIX::O_CREAT | &POSIX::O_WRONLY, 0640 );

               Returns "undef" on failure.

               See also "sysopen" in perlfunc.

       opendir Open a directory for reading.

                       $dir = POSIX::opendir( "/var" );
                       @files = POSIX::readdir( $dir );
                       POSIX::closedir( $dir );

               Returns "undef" on failure.

       pathconf
               Retrieves the value of a configurable limit on a file or directory.

               The following will determine the maximum length of the longest allowable pathname
               on the filesystem which holds "/var".

                       $path_max = POSIX::pathconf( "/var", &POSIX::_PC_PATH_MAX );

               Returns "undef" on failure.

       pause   This is similar to the C function "pause()", which suspends the execution of the
               current process until a signal is received.

               Returns "undef" on failure.

       perror  This is identical to the C function "perror()", which outputs to the standard
               error stream the specified message followed by ": " and the current error string.
               Use the "warn()" function and the $!  variable instead, see "warn" in perlfunc and
               "$ERRNO" in perlvar.

       pipe    Create an interprocess channel.  This returns file descriptors like those returned
               by "POSIX::open".

                       my ($read, $write) = POSIX::pipe();
                       POSIX::write( $write, "hello", 5 );
                       POSIX::read( $read, $buf, 5 );

               See also "pipe" in perlfunc.

       pow     Computes $x raised to the power $exponent.

                       $ret = POSIX::pow( $x, $exponent );

               You can also use the "**" operator, see perlop.

       printf  Formats and prints the specified arguments to STDOUT.  See also "printf" in
               perlfunc.

       putc    putc() is C-specific, see "print" in perlfunc instead.

       putchar putchar() is C-specific, see "print" in perlfunc instead.

       puts    puts() is C-specific, see "print" in perlfunc instead.

       qsort   qsort() is C-specific, see "sort" in perlfunc instead.

       raise   Sends the specified signal to the current process.  See also "kill" in perlfunc
               and the $$ in "$PID" in perlvar.

       rand    "rand()" is non-portable, see "rand" in perlfunc instead.

       read    Read from a file.  This uses file descriptors such as those obtained by calling
               "POSIX::open".  If the buffer $buf is not large enough for the read then Perl will
               extend it to make room for the request.

                       $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
                       $bytes = POSIX::read( $fd, $buf, 3 );

               Returns "undef" on failure.

               See also "sysread" in perlfunc.

       readdir This is identical to Perl's builtin "readdir()" function for reading directory
               entries, see "readdir" in perlfunc.

       realloc realloc() is C-specific.  Perl does memory management transparently.

       remove  This is identical to Perl's builtin "unlink()" function for removing files, see
               "unlink" in perlfunc.

       rename  This is identical to Perl's builtin "rename()" function for renaming files, see
               "rename" in perlfunc.

       rewind  Seeks to the beginning of the file.

       rewinddir
               This is identical to Perl's builtin "rewinddir()" function for rewinding directory
               entry streams, see "rewinddir" in perlfunc.

       rmdir   This is identical to Perl's builtin "rmdir()" function for removing (empty)
               directories, see "rmdir" in perlfunc.

       scanf   scanf() is C-specific, use <> and regular expressions instead, see perlre.

       setgid  Sets the real group identifier and the effective group identifier for this
               process.  Similar to assigning a value to the Perl's builtin $) variable, see
               "$EGID" in perlvar, except that the latter will change only the real user
               identifier, and that the setgid() uses only a single numeric argument, as opposed
               to a space-separated list of numbers.

       setjmp  "setjmp()" is C-specific: use "eval {}" instead, see "eval" in perlfunc.

       setlocale
               Modifies and queries program's locale.  The following examples assume

                       use POSIX qw(setlocale LC_ALL LC_CTYPE);

               has been issued.

               The following will set the traditional UNIX system locale behavior (the second
               argument "C").

                       $loc = setlocale( LC_ALL, "C" );

               The following will query the current LC_CTYPE category.  (No second argument means
               'query'.)

                       $loc = setlocale( LC_CTYPE );

               The following will set the LC_CTYPE behaviour according to the locale environment
               variables (the second argument "").  Please see your systems setlocale(3)
               documentation for the locale environment variables' meaning or consult perllocale.

                       $loc = setlocale( LC_CTYPE, "" );

               The following will set the LC_COLLATE behaviour to Argentinian Spanish. NOTE: The
               naming and availability of locales depends on your operating system. Please
               consult perllocale for how to find out which locales are available in your system.

                       $loc = setlocale( LC_COLLATE, "es_AR.ISO8859-1" );

       setpgid This is similar to the C function "setpgid()" for setting the process group
               identifier of the current process.

               Returns "undef" on failure.

       setsid  This is identical to the C function "setsid()" for setting the session identifier
               of the current process.

       setuid  Sets the real user identifier and the effective user identifier for this process.
               Similar to assigning a value to the Perl's builtin $< variable, see "$UID" in
               perlvar, except that the latter will change only the real user identifier.

       sigaction
               Detailed signal management.  This uses "POSIX::SigAction" objects for the "action"
               and "oldaction" arguments (the oldaction can also be just a hash reference).
               Consult your system's "sigaction" manpage for details, see also "POSIX::SigRt".

               Synopsis:

                       sigaction(signal, action, oldaction = 0)

               Returns "undef" on failure.  The "signal" must be a number (like SIGHUP), not a
               string (like "SIGHUP"), though Perl does try hard to understand you.

               If you use the SA_SIGINFO flag, the signal handler will in addition to the first
               argument, the signal name, also receive a second argument, a hash reference,
               inside which are the following keys with the following semantics, as defined by
               POSIX/SUSv3:

                   signo       the signal number
                   errno       the error number
                   code        if this is zero or less, the signal was sent by
                               a user process and the uid and pid make sense,
                               otherwise the signal was sent by the kernel

               The following are also defined by POSIX/SUSv3, but unfortunately not very widely
               implemented:

                   pid         the process id generating the signal
                   uid         the uid of the process id generating the signal
                   status      exit value or signal for SIGCHLD
                   band        band event for SIGPOLL

               A third argument is also passed to the handler, which contains a copy of the raw
               binary contents of the siginfo structure: if a system has some non-POSIX fields,
               this third argument is where to unpack() them from.

               Note that not all siginfo values make sense simultaneously (some are valid only
               for certain signals, for example), and not all values make sense from Perl
               perspective, you should to consult your system's "sigaction" and possibly also
               "siginfo" documentation.

       siglongjmp
               siglongjmp() is C-specific: use "die" in perlfunc instead.

       sigpending
               Examine signals that are blocked and pending.  This uses "POSIX::SigSet" objects
               for the "sigset" argument.  Consult your system's "sigpending" manpage for
               details.

               Synopsis:

                       sigpending(sigset)

               Returns "undef" on failure.

       sigprocmask
               Change and/or examine calling process's signal mask.  This uses "POSIX::SigSet"
               objects for the "sigset" and "oldsigset" arguments.  Consult your system's
               "sigprocmask" manpage for details.

               Synopsis:

                       sigprocmask(how, sigset, oldsigset = 0)

               Returns "undef" on failure.

               Note that you can't reliably block or unblock a signal from its own signal handler
               if you're using safe signals. Other signals can be blocked or unblocked reliably.

       sigsetjmp
               "sigsetjmp()" is C-specific: use "eval {}" instead, see "eval" in perlfunc.

       sigsuspend
               Install a signal mask and suspend process until signal arrives.  This uses
               "POSIX::SigSet" objects for the "signal_mask" argument.  Consult your system's
               "sigsuspend" manpage for details.

               Synopsis:

                       sigsuspend(signal_mask)

               Returns "undef" on failure.

       sin     This is identical to Perl's builtin "sin()" function for returning the sine of the
               numerical argument, see "sin" in perlfunc.  See also Math::Trig.

       sinh    This is identical to the C function "sinh()" for returning the hyperbolic sine of
               the numerical argument.  See also Math::Trig.

       sleep   This is functionally identical to Perl's builtin "sleep()" function for suspending
               the execution of the current for process for certain number of seconds, see
               "sleep" in perlfunc.  There is one significant difference, however:
               "POSIX::sleep()" returns the number of unslept seconds, while the "CORE::sleep()"
               returns the number of slept seconds.

       sprintf This is similar to Perl's builtin "sprintf()" function for returning a string that
               has the arguments formatted as requested, see "sprintf" in perlfunc.

       sqrt    This is identical to Perl's builtin "sqrt()" function.  for returning the square
               root of the numerical argument, see "sqrt" in perlfunc.

       srand   Give a seed the pseudorandom number generator, see "srand" in perlfunc.

       sscanf  sscanf() is C-specific, use regular expressions instead, see perlre.

       stat    This is identical to Perl's builtin "stat()" function for returning information
               about files and directories.

       strcat  strcat() is C-specific, use ".=" instead, see perlop.

       strchr  strchr() is C-specific, see "index" in perlfunc instead.

       strcmp  strcmp() is C-specific, use "eq" or "cmp" instead, see perlop.

       strcoll This is identical to the C function "strcoll()" for collating (comparing) strings
               transformed using the "strxfrm()" function.  Not really needed since Perl can do
               this transparently, see perllocale.

       strcpy  strcpy() is C-specific, use "=" instead, see perlop.

       strcspn strcspn() is C-specific, use regular expressions instead, see perlre.

       strerror
               Returns the error string for the specified errno.  Identical to the string form of
               the $!, see "$ERRNO" in perlvar.

       strftime
               Convert date and time information to string.  Returns the string.

               Synopsis:

                       strftime(fmt, sec, min, hour, mday, mon, year, wday = -1, yday = -1, isdst = -1)

               The month ("mon"), weekday ("wday"), and yearday ("yday") begin at zero.  I.e.
               January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1.  The year
               ("year") is given in years since 1900.  I.e., the year 1995 is 95; the year 2001
               is 101.  Consult your system's "strftime()" manpage for details about these and
               the other arguments.

               If you want your code to be portable, your format ("fmt") argument should use only
               the conversion specifiers defined by the ANSI C standard (C89, to play safe).
               These are "aAbBcdHIjmMpSUwWxXyYZ%".  But even then, the results of some of the
               conversion specifiers are non-portable.  For example, the specifiers "aAbBcpZ"
               change according to the locale settings of the user, and both how to set locales
               (the locale names) and what output to expect are non-standard.  The specifier "c"
               changes according to the timezone settings of the user and the timezone
               computation rules of the operating system.  The "Z" specifier is notoriously
               unportable since the names of timezones are non-standard. Sticking to the numeric
               specifiers is the safest route.

               The given arguments are made consistent as though by calling "mktime()" before
               calling your system's "strftime()" function, except that the "isdst" value is not
               affected.

               The string for Tuesday, December 12, 1995.

                       $str = POSIX::strftime( "%A, %B %d, %Y", 0, 0, 0, 12, 11, 95, 2 );
                       print "$str\n";

       strlen  strlen() is C-specific, use "length()" instead, see "length" in perlfunc.

       strncat strncat() is C-specific, use ".=" instead, see perlop.

       strncmp strncmp() is C-specific, use "eq" instead, see perlop.

       strncpy strncpy() is C-specific, use "=" instead, see perlop.

       strpbrk strpbrk() is C-specific, use regular expressions instead, see perlre.

       strrchr strrchr() is C-specific, see "rindex" in perlfunc instead.

       strspn  strspn() is C-specific, use regular expressions instead, see perlre.

       strstr  This is identical to Perl's builtin "index()" function, see "index" in perlfunc.

       strtod  String to double translation. Returns the parsed number and the number of
               characters in the unparsed portion of the string.  Truly POSIX-compliant systems
               set $! ($ERRNO) to indicate a translation error, so clear $! before calling
               strtod.  However, non-POSIX systems may not check for overflow, and therefore will
               never set $!.

               strtod should respect any POSIX setlocale() settings.

               To parse a string $str as a floating point number use

                   $! = 0;
                   ($num, $n_unparsed) = POSIX::strtod($str);

               The second returned item and $! can be used to check for valid input:

                   if (($str eq '') || ($n_unparsed != 0) || $!) {
                       die "Non-numeric input $str" . ($! ? ": $!\n" : "\n");
                   }

               When called in a scalar context strtod returns the parsed number.

       strtok  strtok() is C-specific, use regular expressions instead, see perlre, or "split" in
               perlfunc.

       strtol  String to (long) integer translation.  Returns the parsed number and the number of
               characters in the unparsed portion of the string.  Truly POSIX-compliant systems
               set $! ($ERRNO) to indicate a translation error, so clear $! before calling
               strtol.  However, non-POSIX systems may not check for overflow, and therefore will
               never set $!.

               strtol should respect any POSIX setlocale() settings.

               To parse a string $str as a number in some base $base use

                   $! = 0;
                   ($num, $n_unparsed) = POSIX::strtol($str, $base);

               The base should be zero or between 2 and 36, inclusive.  When the base is zero or
               omitted strtol will use the string itself to determine the base: a leading "0x" or
               "0X" means hexadecimal; a leading "0" means octal; any other leading characters
               mean decimal.  Thus, "1234" is parsed as a decimal number, "01234" as an octal
               number, and "0x1234" as a hexadecimal number.

               The second returned item and $! can be used to check for valid input:

                   if (($str eq '') || ($n_unparsed != 0) || !$!) {
                       die "Non-numeric input $str" . $! ? ": $!\n" : "\n";
                   }

               When called in a scalar context strtol returns the parsed number.

       strtoul String to unsigned (long) integer translation.  strtoul() is identical to strtol()
               except that strtoul() only parses unsigned integers.  See "strtol" for details.

               Note: Some vendors supply strtod() and strtol() but not strtoul().  Other vendors
               that do supply strtoul() parse "-1" as a valid value.

       strxfrm String transformation.  Returns the transformed string.

                       $dst = POSIX::strxfrm( $src );

               Used in conjunction with the "strcoll()" function, see "strcoll".

               Not really needed since Perl can do this transparently, see perllocale.

       sysconf Retrieves values of system configurable variables.

               The following will get the machine's clock speed.

                       $clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );

               Returns "undef" on failure.

       system  This is identical to Perl's builtin "system()" function, see "system" in perlfunc.

       tan     This is identical to the C function "tan()", returning the tangent of the
               numerical argument.  See also Math::Trig.

       tanh    This is identical to the C function "tanh()", returning the hyperbolic tangent of
               the numerical argument.   See also Math::Trig.

       tcdrain This is similar to the C function "tcdrain()" for draining the output queue of its
               argument stream.

               Returns "undef" on failure.

       tcflow  This is similar to the C function "tcflow()" for controlling the flow of its
               argument stream.

               Returns "undef" on failure.

       tcflush This is similar to the C function "tcflush()" for flushing the I/O buffers of its
               argument stream.

               Returns "undef" on failure.

       tcgetpgrp
               This is identical to the C function "tcgetpgrp()" for returning the process group
               identifier of the foreground process group of the controlling terminal.

       tcsendbreak
               This is similar to the C function "tcsendbreak()" for sending a break on its
               argument stream.

               Returns "undef" on failure.

       tcsetpgrp
               This is similar to the C function "tcsetpgrp()" for setting the process group
               identifier of the foreground process group of the controlling terminal.

               Returns "undef" on failure.

       time    This is identical to Perl's builtin "time()" function for returning the number of
               seconds since the epoch (whatever it is for the system), see "time" in perlfunc.

       times   The times() function returns elapsed realtime since some point in the past (such
               as system startup), user and system times for this process, and user and system
               times used by child processes.  All times are returned in clock ticks.

                   ($realtime, $user, $system, $cuser, $csystem) = POSIX::times();

               Note: Perl's builtin "times()" function returns four values, measured in seconds.

       tmpfile Use method "IO::File::new_tmpfile()" instead, or see File::Temp.

       tmpnam  Returns a name for a temporary file.

                       $tmpfile = POSIX::tmpnam();

               For security reasons, which are probably detailed in your system's documentation
               for the C library tmpnam() function, this interface should not be used; instead
               see File::Temp.

       tolower This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Consider using the "lc()" function, see "lc" in
               perlfunc, or the equivalent "\L" operator inside doublequotish strings.

       toupper This is identical to the C function, except that it can apply to a single
               character or to a whole string.  Consider using the "uc()" function, see "uc" in
               perlfunc, or the equivalent "\U" operator inside doublequotish strings.

       ttyname This is identical to the C function "ttyname()" for returning the name of the
               current terminal.

       tzname  Retrieves the time conversion information from the "tzname" variable.

                       POSIX::tzset();
                       ($std, $dst) = POSIX::tzname();

       tzset   This is identical to the C function "tzset()" for setting the current timezone
               based on the environment variable "TZ", to be used by "ctime()", "localtime()",
               "mktime()", and "strftime()" functions.

       umask   This is identical to Perl's builtin "umask()" function for setting (and querying)
               the file creation permission mask, see "umask" in perlfunc.

       uname   Get name of current operating system.

                       ($sysname, $nodename, $release, $version, $machine) = POSIX::uname();

               Note that the actual meanings of the various fields are not that well
               standardized, do not expect any great portability.  The $sysname might be the name
               of the operating system, the $nodename might be the name of the host, the $release
               might be the (major) release number of the operating system, the $version might be
               the (minor) release number of the operating system, and the $machine might be a
               hardware identifier.  Maybe.

       ungetc  Use method "IO::Handle::ungetc()" instead.

       unlink  This is identical to Perl's builtin "unlink()" function for removing files, see
               "unlink" in perlfunc.

       utime   This is identical to Perl's builtin "utime()" function for changing the time
               stamps of files and directories, see "utime" in perlfunc.

       vfprintf
               vfprintf() is C-specific, see "printf" in perlfunc instead.

       vprintf vprintf() is C-specific, see "printf" in perlfunc instead.

       vsprintf
               vsprintf() is C-specific, see "sprintf" in perlfunc instead.

       wait    This is identical to Perl's builtin "wait()" function, see "wait" in perlfunc.

       waitpid Wait for a child process to change state.  This is identical to Perl's builtin
               "waitpid()" function, see "waitpid" in perlfunc.

                       $pid = POSIX::waitpid( -1, POSIX::WNOHANG );
                       print "status = ", ($? / 256), "\n";

       wcstombs
               This is identical to the C function "wcstombs()".  Perl does not have any support
               for the wide and multibyte characters of the C standards, so this might be a
               rather useless function.

       wctomb  This is identical to the C function "wctomb()".  Perl does not have any support
               for the wide and multibyte characters of the C standards, so this might be a
               rather useless function.

       write   Write to a file.  This uses file descriptors such as those obtained by calling
               "POSIX::open".

                       $fd = POSIX::open( "foo", &POSIX::O_WRONLY );
                       $buf = "hello";
                       $bytes = POSIX::write( $fd, $buf, 5 );

               Returns "undef" on failure.

               See also "syswrite" in perlfunc.

CLASSES

   POSIX::SigAction
       new     Creates a new "POSIX::SigAction" object which corresponds to the C "struct
               sigaction".  This object will be destroyed automatically when it is no longer
               needed.  The first parameter is the handler, a sub reference.  The second
               parameter is a "POSIX::SigSet" object, it defaults to the empty set.  The third
               parameter contains the "sa_flags", it defaults to 0.

                       $sigset = POSIX::SigSet->new(SIGINT, SIGQUIT);
                       $sigaction = POSIX::SigAction->new( \&handler, $sigset, &POSIX::SA_NOCLDSTOP );

               This "POSIX::SigAction" object is intended for use with the "POSIX::sigaction()"
               function.

       handler
       mask
       flags   accessor functions to get/set the values of a SigAction object.

                       $sigset = $sigaction->mask;
                       $sigaction->flags(&POSIX::SA_RESTART);

       safe    accessor function for the "safe signals" flag of a SigAction object; see perlipc
               for general information on safe (a.k.a. "deferred") signals.  If you wish to
               handle a signal safely, use this accessor to set the "safe" flag in the
               "POSIX::SigAction" object:

                       $sigaction->safe(1);

               You may also examine the "safe" flag on the output action object which is filled
               in when given as the third parameter to "POSIX::sigaction()":

                       sigaction(SIGINT, $new_action, $old_action);
                       if ($old_action->safe) {
                           # previous SIGINT handler used safe signals
                       }

   POSIX::SigRt
       %SIGRT  A hash of the POSIX realtime signal handlers.  It is an extension of the standard
               %SIG, the $POSIX::SIGRT{SIGRTMIN} is roughly equivalent to $SIG{SIGRTMIN}, but the
               right POSIX moves (see below) are made with the POSIX::SigSet and POSIX::sigaction
               instead of accessing the %SIG.

               You can set the %POSIX::SIGRT elements to set the POSIX realtime signal handlers,
               use "delete" and "exists" on the elements, and use "scalar" on the %POSIX::SIGRT
               to find out how many POSIX realtime signals there are available (SIGRTMAX -
               SIGRTMIN + 1, the SIGRTMAX is a valid POSIX realtime signal).

               Setting the %SIGRT elements is equivalent to calling this:

                 sub new {
                   my ($rtsig, $handler, $flags) = @_;
                   my $sigset = POSIX::SigSet($rtsig);
                   my $sigact = POSIX::SigAction->new($handler, $sigset, $flags);
                   sigaction($rtsig, $sigact);
                 }

               The flags default to zero, if you want something different you can either use
               "local" on $POSIX::SigRt::SIGACTION_FLAGS, or you can derive from POSIX::SigRt and
               define your own "new()" (the tied hash STORE method of the %SIGRT calls
               "new($rtsig, $handler, $SIGACTION_FLAGS)", where the $rtsig ranges from zero to
               SIGRTMAX - SIGRTMIN + 1).

               Just as with any signal, you can use sigaction($rtsig, undef, $oa) to retrieve the
               installed signal handler (or, rather, the signal action).

               NOTE: whether POSIX realtime signals really work in your system, or whether Perl
               has been compiled so that it works with them, is outside of this discussion.

       SIGRTMIN
               Return the minimum POSIX realtime signal number available, or "undef" if no POSIX
               realtime signals are available.

       SIGRTMAX
               Return the maximum POSIX realtime signal number available, or "undef" if no POSIX
               realtime signals are available.

   POSIX::SigSet
       new     Create a new SigSet object.  This object will be destroyed automatically when it
               is no longer needed.  Arguments may be supplied to initialize the set.

               Create an empty set.

                       $sigset = POSIX::SigSet->new;

               Create a set with SIGUSR1.

                       $sigset = POSIX::SigSet->new( &POSIX::SIGUSR1 );

       addset  Add a signal to a SigSet object.

                       $sigset->addset( &POSIX::SIGUSR2 );

               Returns "undef" on failure.

       delset  Remove a signal from the SigSet object.

                       $sigset->delset( &POSIX::SIGUSR2 );

               Returns "undef" on failure.

       emptyset
               Initialize the SigSet object to be empty.

                       $sigset->emptyset();

               Returns "undef" on failure.

       fillset Initialize the SigSet object to include all signals.

                       $sigset->fillset();

               Returns "undef" on failure.

       ismember
               Tests the SigSet object to see if it contains a specific signal.

                       if( $sigset->ismember( &POSIX::SIGUSR1 ) ){
                               print "contains SIGUSR1\n";
                       }

   POSIX::Termios
       new     Create a new Termios object.  This object will be destroyed automatically when it
               is no longer needed.  A Termios object corresponds to the termios C struct.  new()
               mallocs a new one, getattr() fills it from a file descriptor, and setattr() sets a
               file descriptor's parameters to match Termios' contents.

                       $termios = POSIX::Termios->new;

       getattr Get terminal control attributes.

               Obtain the attributes for stdin.

                       $termios->getattr( 0 ) # Recommended for clarity.
                       $termios->getattr()

               Obtain the attributes for stdout.

                       $termios->getattr( 1 )

               Returns "undef" on failure.

       getcc   Retrieve a value from the c_cc field of a termios object.  The c_cc field is an
               array so an index must be specified.

                       $c_cc[1] = $termios->getcc(1);

       getcflag
               Retrieve the c_cflag field of a termios object.

                       $c_cflag = $termios->getcflag;

       getiflag
               Retrieve the c_iflag field of a termios object.

                       $c_iflag = $termios->getiflag;

       getispeed
               Retrieve the input baud rate.

                       $ispeed = $termios->getispeed;

       getlflag
               Retrieve the c_lflag field of a termios object.

                       $c_lflag = $termios->getlflag;

       getoflag
               Retrieve the c_oflag field of a termios object.

                       $c_oflag = $termios->getoflag;

       getospeed
               Retrieve the output baud rate.

                       $ospeed = $termios->getospeed;

       setattr Set terminal control attributes.

               Set attributes immediately for stdout.

                       $termios->setattr( 1, &POSIX::TCSANOW );

               Returns "undef" on failure.

       setcc   Set a value in the c_cc field of a termios object.  The c_cc field is an array so
               an index must be specified.

                       $termios->setcc( &POSIX::VEOF, 1 );

       setcflag
               Set the c_cflag field of a termios object.

                       $termios->setcflag( $c_cflag | &POSIX::CLOCAL );

       setiflag
               Set the c_iflag field of a termios object.

                       $termios->setiflag( $c_iflag | &POSIX::BRKINT );

       setispeed
               Set the input baud rate.

                       $termios->setispeed( &POSIX::B9600 );

               Returns "undef" on failure.

       setlflag
               Set the c_lflag field of a termios object.

                       $termios->setlflag( $c_lflag | &POSIX::ECHO );

       setoflag
               Set the c_oflag field of a termios object.

                       $termios->setoflag( $c_oflag | &POSIX::OPOST );

       setospeed
               Set the output baud rate.

                       $termios->setospeed( &POSIX::B9600 );

               Returns "undef" on failure.

       Baud rate values
               B38400 B75 B200 B134 B300 B1800 B150 B0 B19200 B1200 B9600 B600 B4800 B50 B2400
               B110

       Terminal interface values
               TCSADRAIN TCSANOW TCOON TCIOFLUSH TCOFLUSH TCION TCIFLUSH TCSAFLUSH TCIOFF TCOOFF

       c_cc field values
               VEOF VEOL VERASE VINTR VKILL VQUIT VSUSP VSTART VSTOP VMIN VTIME NCCS

       c_cflag field values
               CLOCAL CREAD CSIZE CS5 CS6 CS7 CS8 CSTOPB HUPCL PARENB PARODD

       c_iflag field values
               BRKINT ICRNL IGNBRK IGNCR IGNPAR INLCR INPCK ISTRIP IXOFF IXON PARMRK

       c_lflag field values
               ECHO ECHOE ECHOK ECHONL ICANON IEXTEN ISIG NOFLSH TOSTOP

       c_oflag field values
               OPOST

PATHNAME CONSTANTS

       Constants
               _PC_CHOWN_RESTRICTED _PC_LINK_MAX _PC_MAX_CANON _PC_MAX_INPUT _PC_NAME_MAX
               _PC_NO_TRUNC _PC_PATH_MAX _PC_PIPE_BUF _PC_VDISABLE

POSIX CONSTANTS

       Constants
               _POSIX_ARG_MAX _POSIX_CHILD_MAX _POSIX_CHOWN_RESTRICTED _POSIX_JOB_CONTROL
               _POSIX_LINK_MAX _POSIX_MAX_CANON _POSIX_MAX_INPUT _POSIX_NAME_MAX
               _POSIX_NGROUPS_MAX _POSIX_NO_TRUNC _POSIX_OPEN_MAX _POSIX_PATH_MAX _POSIX_PIPE_BUF
               _POSIX_SAVED_IDS _POSIX_SSIZE_MAX _POSIX_STREAM_MAX _POSIX_TZNAME_MAX
               _POSIX_VDISABLE _POSIX_VERSION

SYSTEM CONFIGURATION

       Constants
               _SC_ARG_MAX _SC_CHILD_MAX _SC_CLK_TCK _SC_JOB_CONTROL _SC_NGROUPS_MAX _SC_OPEN_MAX
               _SC_PAGESIZE _SC_SAVED_IDS _SC_STREAM_MAX _SC_TZNAME_MAX _SC_VERSION

ERRNO

       Constants
               E2BIG EACCES EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF EBUSY
               ECHILD ECONNABORTED ECONNREFUSED ECONNRESET EDEADLK EDESTADDRREQ EDOM EDQUOT
               EEXIST EFAULT EFBIG EHOSTDOWN EHOSTUNREACH EINPROGRESS EINTR EINVAL EIO EISCONN
               EISDIR ELOOP EMFILE EMLINK EMSGSIZE ENAMETOOLONG ENETDOWN ENETRESET ENETUNREACH
               ENFILE ENOBUFS ENODEV ENOENT ENOEXEC ENOLCK ENOMEM ENOPROTOOPT ENOSPC ENOSYS
               ENOTBLK ENOTCONN ENOTDIR ENOTEMPTY ENOTSOCK ENOTTY ENXIO EOPNOTSUPP EPERM
               EPFNOSUPPORT EPIPE EPROCLIM EPROTONOSUPPORT EPROTOTYPE ERANGE EREMOTE ERESTART
               EROFS ESHUTDOWN ESOCKTNOSUPPORT ESPIPE ESRCH ESTALE ETIMEDOUT ETOOMANYREFS ETXTBSY
               EUSERS EWOULDBLOCK EXDEV

FCNTL

       Constants
               FD_CLOEXEC F_DUPFD F_GETFD F_GETFL F_GETLK F_OK F_RDLCK F_SETFD F_SETFL F_SETLK
               F_SETLKW F_UNLCK F_WRLCK O_ACCMODE O_APPEND O_CREAT O_EXCL O_NOCTTY O_NONBLOCK
               O_RDONLY O_RDWR O_TRUNC O_WRONLY

FLOAT

       Constants
               DBL_DIG DBL_EPSILON DBL_MANT_DIG DBL_MAX DBL_MAX_10_EXP DBL_MAX_EXP DBL_MIN
               DBL_MIN_10_EXP DBL_MIN_EXP FLT_DIG FLT_EPSILON FLT_MANT_DIG FLT_MAX FLT_MAX_10_EXP
               FLT_MAX_EXP FLT_MIN FLT_MIN_10_EXP FLT_MIN_EXP FLT_RADIX FLT_ROUNDS LDBL_DIG
               LDBL_EPSILON LDBL_MANT_DIG LDBL_MAX LDBL_MAX_10_EXP LDBL_MAX_EXP LDBL_MIN
               LDBL_MIN_10_EXP LDBL_MIN_EXP

LIMITS

       Constants
               ARG_MAX CHAR_BIT CHAR_MAX CHAR_MIN CHILD_MAX INT_MAX INT_MIN LINK_MAX LONG_MAX
               LONG_MIN MAX_CANON MAX_INPUT MB_LEN_MAX NAME_MAX NGROUPS_MAX OPEN_MAX PATH_MAX
               PIPE_BUF SCHAR_MAX SCHAR_MIN SHRT_MAX SHRT_MIN SSIZE_MAX STREAM_MAX TZNAME_MAX
               UCHAR_MAX UINT_MAX ULONG_MAX USHRT_MAX

LOCALE

       Constants
               LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME

MATH

       Constants
               HUGE_VAL

SIGNAL

       Constants
               SA_NOCLDSTOP SA_NOCLDWAIT SA_NODEFER SA_ONSTACK SA_RESETHAND SA_RESTART SA_SIGINFO
               SIGABRT SIGALRM SIGCHLD SIGCONT SIGFPE SIGHUP SIGILL SIGINT SIGKILL SIGPIPE
               SIGQUIT SIGSEGV SIGSTOP SIGTERM SIGTSTP SIGTTIN SIGTTOU SIGUSR1 SIGUSR2 SIG_BLOCK
               SIG_DFL SIG_ERR SIG_IGN SIG_SETMASK SIG_UNBLOCK

STAT

       Constants
               S_IRGRP S_IROTH S_IRUSR S_IRWXG S_IRWXO S_IRWXU S_ISGID S_ISUID S_IWGRP S_IWOTH
               S_IWUSR S_IXGRP S_IXOTH S_IXUSR

       Macros  S_ISBLK S_ISCHR S_ISDIR S_ISFIFO S_ISREG

STDLIB

       Constants
               EXIT_FAILURE EXIT_SUCCESS MB_CUR_MAX RAND_MAX

STDIO

       Constants
               BUFSIZ EOF FILENAME_MAX L_ctermid L_cuserid L_tmpname TMP_MAX

TIME

       Constants
               CLK_TCK CLOCKS_PER_SEC

UNISTD

       Constants
               R_OK SEEK_CUR SEEK_END SEEK_SET STDIN_FILENO STDOUT_FILENO STDERR_FILENO W_OK X_OK

WAIT

       Constants
               WNOHANG WUNTRACED

               WNOHANG         Do not suspend the calling process until a child process changes
                               state but instead return immediately.

               WUNTRACED       Catch stopped child processes.

       Macros  WIFEXITED WEXITSTATUS WIFSIGNALED WTERMSIG WIFSTOPPED WSTOPSIG

               WIFEXITED       WIFEXITED(${^CHILD_ERROR_NATIVE}) returns true if the child
                               process exited normally ("exit()" or by falling off the end of
                               "main()")

               WEXITSTATUS     WEXITSTATUS(${^CHILD_ERROR_NATIVE}) returns the normal exit status
                               of the child process (only meaningful if
                               WIFEXITED(${^CHILD_ERROR_NATIVE}) is true)

               WIFSIGNALED     WIFSIGNALED(${^CHILD_ERROR_NATIVE}) returns true if the child
                               process terminated because of a signal

               WTERMSIG        WTERMSIG(${^CHILD_ERROR_NATIVE}) returns the signal the child
                               process terminated for (only meaningful if
                               WIFSIGNALED(${^CHILD_ERROR_NATIVE}) is true)

               WIFSTOPPED      WIFSTOPPED(${^CHILD_ERROR_NATIVE}) returns true if the child
                               process is currently stopped (can happen only if you specified the
                               WUNTRACED flag to waitpid())

               WSTOPSIG        WSTOPSIG(${^CHILD_ERROR_NATIVE}) returns the signal the child
                               process was stopped for (only meaningful if
                               WIFSTOPPED(${^CHILD_ERROR_NATIVE}) is true)