POSIX - Perl interface to IEEE Std 1003.1
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
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. Things which are
#defines
in
C, like
EINTR or
O_NDELAY, are automatically exported into your namespace. All functions are only exported if you ask for them explicitly. Most likely people will prefer to use the fully-qualified function names.
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 the perlfunc manpage 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.
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.
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.
_exit()
.
abort()
.
if( POSIX::access( "/", &POSIX::R_OK ) ){ print "have read permission\n"; }
Returns undef on failure.
acos()
.
asctime()
.
asin()
.
atan()
.
atexit()
is C-specific: use
END {} instead.
atof()
is C-specific.
atoi()
is C-specific.
atol()
is C-specific.
bsearch()
not supplied.
calloc()
is C-specific.
ceil()
.
IO::Handle::clearerr()
instead.
clock()
.
POSIX::open
.
$fd = POSIX::open( "foo", &POSIX::O_RDONLY ); POSIX::close( $fd );
Returns undef on failure.
cosh()
.
POSIX::open
. Use POSIX::close
to close the file.
$fd = POSIX::creat( "foo", 0611 ); POSIX::close( $fd );
$path = POSIX::ctermid();
ctime()
.
$name = POSIX::cuserid();
difftime()
.
div()
is C-specific.
dup()
.
This uses file descriptors such as those obtained by calling
POSIX::open
.
Returns undef on failure.
dup2()
.
This uses file descriptors such as those obtained by calling
POSIX::open
.
Returns undef on failure.
$errno = POSIX::errno();
execl()
is C-specific.
execle()
is C-specific.
execlp()
is C-specific.
execv()
is C-specific.
execve()
is C-specific.
execvp()
is C-specific.
IO::Handle::close()
instead.
IO::Handle::new_from_fd()
instead.
IO::Handle::eof()
instead.
IO::Handle::error()
instead.
IO::Handle::flush()
instead.
IO::Handle::getc()
instead.
IO::Seekable::getpos()
instead.
IO::Handle::gets()
instead.
IO::Handle::fileno()
instead.
floor()
.
fmod()
.
IO::File::open()
instead.
POSIX::open
.
The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds /tmp/foo
.
$fd = POSIX::open( "/tmp/foo", &POSIX::O_RDONLY ); $path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX );
Returns undef on failure.
fprintf()
is C-specific--use
printf instead.
fputc()
is C-specific--use
print instead.
fputs()
is C-specific--use
print instead.
fread()
is C-specific--use
read instead.
free()
is C-specific.
freopen()
is C-specific--use
open instead.
($mantissa, $exponent) = POSIX::frexp( 3.14 );
fscanf()
is C-specific--use
<> and regular expressions instead.
IO::Seekable::seek()
instead.
IO::Seekable::setpos()
instead.
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 );
IO::Seekable::tell()
instead.
fwrite()
is C-specific--use
print instead.
labs()
is C-specific, use abs
instead.
ldexp()
.
ldiv()
is C-specific, use / and
int instead.
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";
log10()
.
longjmp()
is C-specific: use
die instead.
POSIX::open
.
$fd = POSIX::open( "foo", &POSIX::O_RDONLY ); $off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET );
Returns undef on failure.
malloc()
is C-specific.
mblen()
.
mbstowcs()
.
mbtowc()
.
memchr()
is C-specific, use
index()
instead.
memcmp()
is C-specific, use
eq instead.
memcpy()
is C-specific, use =
instead.
memmove()
is C-specific, use
= instead.
memset()
is C-specific, use x
instead.
mkfifo()
.
Returns undef on failure.
Synopsis:
mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = 0)
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.
($fractional, $integral) = POSIX::modf( 3.14 );
nice()
.
Returns undef on failure.
offsetof()
is C-specific.
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.
$dir = POSIX::opendir( "/tmp" ); @files = POSIX::readdir( $dir ); POSIX::closedir( $dir );
Returns undef on failure.
The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds /tmp
.
$path_max = POSIX::pathconf( "/tmp", &POSIX::_PC_PATH_MAX );
Returns undef on failure.
pause()
.
Returns undef on failure.
perror()
.
POSIX::open
.
($fd0, $fd1) = POSIX::pipe(); POSIX::write( $fd0, "hello", 5 ); POSIX::read( $fd1, $buf, 5 );
$x
raised to the power $exponent.
$ret = POSIX::pow( $x, $exponent );
putc()
is C-specific--use print
instead.
putchar()
is C-specific--use
print instead.
puts()
is C-specific--use print
instead.
qsort()
is C-specific, use
sort instead.
rand()
is non-portable, use
Perl's rand instead.
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.
realloc()
is C-specific.
scanf()
is C-specific--use
<> and regular expressions instead.
setjmp()
is C-specific: use
eval {} instead.
The following will set the traditional UNIX system locale behavior (the second argument "C").
$loc = POSIX::setlocale( &POSIX::LC_ALL, "C" );
The following will query (the missing second argument) the current LC_CTYPE category.
$loc = POSIX::setlocale( &POSIX::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 the perllocale manpage.
$loc = POSIX::setlocale( &POSIX::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 the perllocale manpage for how to find out which locales are available in your system.
$loc = POSIX::setlocale( &POSIX::LC_ALL, "es_AR.ISO8859-1" );
setpgid()
.
Returns undef on failure.
setsid()
.
POSIX::SigAction
objects for the
action
and oldaction
arguments. Consult your system's sigaction
manpage for details.
Synopsis:
sigaction(sig, action, oldaction = 0)
Returns undef on failure.
siglongjmp()
is
C-specific: use die instead.
POSIX::SigSet
objects for the sigset
argument. Consult your system's sigpending
manpage for details.
Synopsis:
sigpending(sigset)
Returns undef on failure.
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.
sigsetjmp()
is C-specific:
use eval {} instead.
POSIX::SigSet
objects for the signal_mask
argument. Consult your system's sigsuspend
manpage for details.
Synopsis:
sigsuspend(signal_mask)
Returns undef on failure.
sinh()
.
srand().
sscanf()
is C-specific--use
regular expressions instead.
strcat()
is C-specific, use
.= instead.
strchr()
is C-specific, use
index()
instead.
strcmp()
is C-specific, use
eq instead.
strcoll()
.
strcpy()
is C-specific, use =
instead.
strcspn()
is C-specific, use
regular expressions instead.
Synopsis:
strftime(fmt, sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = 0)
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.
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()
is C-specific, use
length instead.
strncat()
is C-specific, use
.= instead.
strncmp()
is C-specific, use
eq instead.
strncpy()
is C-specific, use
= instead.
stroul()
is C-specific.
strpbrk()
is C-specific.
strrchr()
is C-specific, use
rindex()
instead.
strspn()
is C-specific.
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()
is C-specific.
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.
Note: Some vendors supply strtod and strtol but not strtoul. Other vendors that do suply strtoul parse ``-1'' as a valid value.
$dst = POSIX::strxfrm( $src );
The following will get the machine's clock speed.
$clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );
Returns undef on failure.
tan()
.
tanh()
.
tcdrain()
.
Returns undef on failure.
tcflow()
.
Returns undef on failure.
tcflush()
.
Returns undef on failure.
tcgetpgrp()
.
tcsendbreak()
.
Returns undef on failure.
tcsetpgrp()
.
Returns undef on failure.
times()
function returns
elapsed realtime since some point in the past (such as system startup),
user and system times for this process, and user and system times used by
child processes. All times are returned in clock ticks.
($realtime, $user, $system, $cuser, $csystem) = POSIX::times();
Note: Perl's builtin times() function returns four values, measured in seconds.
IO::File::new_tmpfile()
instead.
$tmpfile = POSIX::tmpnam();
ttyname()
.
tzname
variable.
POSIX::tzset(); ($std, $dst) = POSIX::tzname();
tzset()
.
($sysname, $nodename, $release, $version, $machine ) = POSIX::uname();
IO::Handle::ungetc()
instead.
vfprintf()
is C-specific.
vprintf()
is C-specific.
vsprintf()
is C-specific.
$pid = POSIX::waitpid( -1, &POSIX::WNOHANG ); print "status = ", ($? / 256), "\n";
wcstombs()
.
wctomb()
.
POSIX::open
.
$fd = POSIX::open( "foo", &POSIX::O_WRONLY ); $buf = "hello"; $bytes = POSIX::write( $b, $buf, 5 );
Returns undef on failure.
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 fully-qualified name of a sub which is a
signal-handler. 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( 'main::handler', $sigset, &POSIX::SA_NOCLDSTOP );
This POSIX::SigAction
object should be used with the POSIX::sigaction()
function.
Create an empty set.
$sigset = POSIX::SigSet->new;
Create a set with SIGUSR1.
$sigset = POSIX::SigSet->new( &POSIX::SIGUSR1 );
$sigset->addset( &POSIX::SIGUSR2 );
Returns undef on failure.
$sigset->delset( &POSIX::SIGUSR2 );
Returns undef on failure.
$sigset->emptyset();
Returns undef on failure.
$sigset->fillset();
Returns undef on failure.
if( $sigset->ismember( &POSIX::SIGUSR1 ) ){ print "contains SIGUSR1\n"; }
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;
Obtain the attributes for stdin.
$termios->getattr()
Obtain the attributes for stdout.
$termios->getattr( 1 )
Returns undef on failure.
$c_cc[1] = $termios->getcc(1);
$c_cflag = $termios->getcflag;
$c_iflag = $termios->getiflag;
$ispeed = $termios->getispeed;
$c_lflag = $termios->getlflag;
$c_oflag = $termios->getoflag;
$ospeed = $termios->getospeed;
Set attributes immediately for stdout.
$termios->setattr( 1, &POSIX::TCSANOW );
Returns undef on failure.
$termios->setcc( &POSIX::VEOF, 1 );
$termios->setcflag( $c_cflag | &POSIX::CLOCAL );
$termios->setiflag( $c_iflag | &POSIX::BRKINT );
$termios->setispeed( &POSIX::B9600 );
Returns undef on failure.
$termios->setlflag( $c_lflag | &POSIX::ECHO );
$termios->setoflag( $c_oflag | &POSIX::OPOST );
$termios->setospeed( &POSIX::B9600 );
Returns undef on failure.
This document generated by ./mkposixman.PL version 19960129.
If rather than formatting bugs, you encounter substantive content errors in these documents, such as mistakes in the explanations or code, please use the perlbug utility included with the Perl distribution.