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POSIX - Perl interface to IEEE Std 1003.1
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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
-
This is identical to the C function
_exit(). It exits the program
immediately which means among other things buffered I/O is not flushed.
- 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 the Math::Trig manpage.
- 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. The $wday, $yday, and $isdst
default to zero (and the first two are usually ignored anyway).
- asin
-
This is identical to the C function
asin(), returning
the arcus sine of its numerical argument. See also the Math::Trig manpage.
- assert
-
Unimplemented, but you can use die in the perlfunc manpage and the the Carp manpage module
to achieve similar things.
- atan
-
This is identical to the C function
atan(), returning the
arcus tangent of its numerical argument. See also the Math::Trig manpage.
- 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 the Math::Trig manpage.
- atexit
-
atexit() is C-specific: use END {} instead, see the perlsub manpage.
- 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 the perlfunc manpage.
- 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 the perlfunc manpage.
- bsearch
-
bsearch() not supplied. For doing binary search on wordlists,
see the Search::Dict manpage.
- 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 the perlfunc manpage.
- chmod
-
This is identical to Perl's builtin
chmod() function, allowing
one to change file and directory permissions, see chmod in the perlfunc manpage.
- chown
-
This is identical to Perl's builtin
chown() function, allowing one
to change file and directory owners and groups, see chown in the perlfunc manpage.
- clearerr
-
Use the method the IO::Handle::clearerr() manpage 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 the perlfunc manpage.
- closedir
-
This is identical to Perl's builtin
closedir() function for closing
a directory handle, see closedir in the perlfunc manpage.
- cos
-
This is identical to Perl's builtin
cos() function, for returning
the cosine of its numerical argument, see cos in the perlfunc manpage.
See also the Math::Trig manpage.
- cosh
-
This is identical to the C function
cosh(), for returning
the hyperbolic cosine of its numeric argument. See also the Math::Trig manpage.
- 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 the perlfunc manpage 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 the perlfunc manpage 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 the perlvar manpage.
- execl
-
execl() is C-specific, see exec in the perlfunc manpage.
- execle
-
execle() is C-specific, see exec in the perlfunc manpage.
- execlp
-
execlp() is C-specific, see exec in the perlfunc manpage.
- execv
-
execv() is C-specific, see exec in the perlfunc manpage.
- execve
-
execve() is C-specific, see exec in the perlfunc manpage.
- execvp
-
execvp() is C-specific, see exec in the perlfunc manpage.
- exit
-
This is identical to Perl's builtin
exit() function for exiting the
program, see exit in the perlfunc manpage.
- exp
-
This is identical to Perl's builtin
exp() function for
returning the exponent (e-based) of the numerical argument,
see exp in the perlfunc manpage.
- fabs
-
This is identical to Perl's builtin
abs() function for returning
the absolute value of the numerical argument, see abs in the perlfunc manpage.
- fclose
-
Use method
IO::Handle::close() instead, or see close in the perlfunc manpage.
- fcntl
-
This is identical to Perl's builtin
fcntl() function,
see fcntl in the perlfunc manpage.
- fdopen
-
Use method
IO::Handle::new_from_fd() instead, or see open in the perlfunc manpage.
- feof
-
Use method
IO::Handle::eof() instead, or see eof in the perlfunc manpage.
- ferror
-
Use method
IO::Handle::error() instead.
- fflush
-
Use method
IO::Handle::flush() instead.
See also $OUTPUT_AUTOFLUSH in the perlvar manpage.
- fgetc
-
Use method
IO::Handle::getc() instead, or see read in the perlfunc manpage.
- fgetpos
-
Use method
IO::Seekable::getpos() instead, or see seek in the L manpage.
- fgets
-
Use method
IO::Handle::gets() instead. Similar to <>, also known
as readline in the perlfunc manpage.
- fileno
-
Use method
IO::Handle::fileno() instead, or see fileno in the perlfunc manpage.
- 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().
$r = modf($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 the perlfunc manpage.
- fork
-
This is identical to Perl's builtin
fork() function
for duplicating the current process, see fork in the perlfunc manpage
and the perlfork manpage 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 /tmp/foo.
$fd = POSIX::open( "/tmp/foo", &POSIX::O_RDONLY );
$path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX );
Returns undef on failure.
- fprintf
-
fprintf() is C-specific, see printf in the perlfunc manpage instead.
- fputc
-
fputc() is C-specific, see print in the perlfunc manpage instead.
- fputs
-
fputs() is C-specific, see print in the perlfunc manpage instead.
- fread
-
fread() is C-specific, see read in the perlfunc manpage instead.
- free
-
free() is C-specific. Perl does memory management transparently.
- freopen
-
freopen() is C-specific, see open in the perlfunc manpage instead.
- frexp
-
Return the mantissa and exponent of a floating-point number.
($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 the perlfunc manpage.
- fsetpos
-
Use method
IO::Seekable::setpos() instead, or seek seek in the perlfunc manpage.
- 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 );
- ftell
-
Use method
IO::Seekable::tell() instead, or see tell in the perlfunc manpage.
- fwrite
-
fwrite() is C-specific, see print in the perlfunc manpage instead.
- getc
-
This is identical to Perl's builtin
getc() function,
see getc in the perlfunc manpage.
- getchar
-
Returns one character from STDIN. Identical to Perl's
getc(),
see getc in the perlfunc manpage.
- getcwd
-
Returns the name of the current working directory.
See also the Cwd manpage.
- getegid
-
Returns the effective group identifier. Similar to Perl' s builtin
variable
$(, see $EGID in the perlvar manpage.
- getenv
-
Returns the value of the specified enironment 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 the perlvar manpage.
- getgid
-
Returns the user's real group identifier. Similar to Perl's builtin
variable
$), see $GID in the perlvar manpage.
- getgrgid
-
This is identical to Perl's builtin
getgrgid() function for
returning group entries by group identifiers, see
getgrgid in the perlfunc manpage.
- getgrnam
-
This is identical to Perl's builtin
getgrnam() function for
returning group entries by group names, see getgrnam in the perlfunc manpage.
- getgroups
-
Returns the ids of the user's supplementary groups. Similar to Perl's
builtin variable
$), see $GID in the perlvar manpage.
- getlogin
-
This is identical to Perl's builtin
getlogin() function for
returning the user name associated with the current session, see
getlogin in the perlfunc manpage.
- getpgrp
-
This is identical to Perl's builtin
getpgrp() function for
returning the prcess group identifier of the current process, see
getpgrp in the perlfunc manpage.
- getpid
-
Returns the process identifier. Identical to Perl's builtin
variable
$$, see $PID in the perlvar manpage.
- 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 the perlfunc manpage.
- getpwnam
-
This is identical to Perl's builtin
getpwnam() function for
returning user entries by user names, see getpwnam in the perlfunc manpage.
- getpwuid
-
This is identical to Perl's builtin
getpwuid() function for
returning user entries by user identifiers, see getpwuid in the perlfunc manpage.
- gets
-
Returns one line from
STDIN, similar to <>, also known
as the readline() function, see readline in the perlfunc manpage.
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 the perlvar manpage.
- 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 the perlfunc manpage.
- isalnum
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using regular expressions and the
/[[:isalnum:]]/ 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. Consider using regular expressions and the
/[[:isalpha:]]/ construct instead.
- isatty
-
Returns a boolean indicating whether the specified filehandle is connected
to a tty. Similar to the
-t operator, see -X in the perlfunc manpage.
- iscntrl
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using regular expressions and the
/[[:iscntrl:]]/ construct instead.
- isdigit
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using regular expressions and the
/[[:isdigit:]]/ 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. Consider using regular expressions and the
/[[:isgraph:]]/ construct instead.
- islower
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using regular expressions and the
/[[:islower:]]/ 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. Consider using regular expressions and the
/[[:isprint:]]/ construct instead.
- ispunct
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using regular expressions and the
/[[:ispunct:]]/ construct instead.
- isspace
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using regular expressions and the
/[[:isspace:]]/ construct instead, or the /\s/ construct.
- isupper
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using regular expressions and the
/[[:isupper:]]/ 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. Consider using regular expressions and the
/[[:isxdigit:]]/ 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 the perlfunc manpage.
- labs
-
(For returning absolute values of long integers.)
labs() is C-specific, see abs in the perlfunc manpage instead.
- 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 the perlfunc manpage.
- 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 the perlfunc manpage.
- log
-
This is identical to Perl's builtin
log() function,
returning the natural (e-based) logarithm of the numerical argument,
see log in the perlfunc manpage.
- 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 the perlfunc manpage 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 the perlfunc manpage instead.
- memcmp
-
memcmp() is C-specific, use eq instead, see the perlop manpage.
- memcpy
-
memcpy() is C-specific, use =, see the perlop manpage, or see substr in the perlfunc manpage.
- memmove
-
memmove() is C-specific, use =, see the perlop manpage, or see substr in the perlfunc manpage.
- memset
-
memset() is C-specific, use x instead, see the perlop manpage.
- mkdir
-
This is identical to Perl's builtin
mkdir() function
for creating directories, see mkdir in the perlfunc manpage.
- 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 the perlfunc manpage.
- mktime
-
Convert date/time info to a calendar time.
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.
- 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 the perlfunc manpage 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 the perlfunc manpage.
- opendir
-
Open a directory for reading.
$dir = POSIX::opendir( "/tmp" );
@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 /tmp.
$path_max = POSIX::pathconf( "/tmp", &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 the perlfunc manpage and $ERRNO in the perlvar manpage.
- pipe
-
Create an interprocess channel. This returns file descriptors like those
returned by
POSIX::open.
($fd0, $fd1) = POSIX::pipe();
POSIX::write( $fd0, "hello", 5 );
POSIX::read( $fd1, $buf, 5 );
See also pipe in the perlfunc manpage.
- pow
-
Computes
$x raised to the power $exponent.
$ret = POSIX::pow( $x, $exponent );
You can also use the ** operator, see the perlop manpage.
- printf
-
Formats and prints the specified arguments to STDOUT.
See also printf in the perlfunc manpage.
- putc
-
putc() is C-specific, see print in the perlfunc manpage instead.
- putchar
-
putchar() is C-specific, see print in the perlfunc manpage instead.
- puts
-
puts() is C-specific, see print in the perlfunc manpage instead.
- qsort
-
qsort() is C-specific, see sort in the perlfunc manpage instead.
- raise
-
Sends the specified signal to the current process.
See also kill in the perlfunc manpage and the
$$ in $PID in the perlvar manpage.
- rand
-
rand() is non-portable, see rand in the perlfunc manpage 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 the perlfunc manpage.
- readdir
-
This is identical to Perl's builtin
readdir() function
for reading directory entries, see readdir in the perlfunc manpage.
- 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 the perlfunc manpage.
- rename
-
This is identical to Perl's builtin
rename() function
for renaming files, see rename in the perlfunc manpage.
- 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 the perlfunc manpage.
- rmdir
-
This is identical to Perl's builtin
rmdir() function
for removing (empty) directories, see rmdir in the perlfunc manpage.
- scanf
-
scanf() is C-specific, use <> and regular expressions instead,
see the perlre manpage.
- setgid
-
Sets the real group identifier for this process.
Identical to assigning a value to the Perl's builtin
$) variable,
see $UID in the perlvar manpage.
- setjmp
-
setjmp() is C-specific: use eval {} instead,
see eval in the perlfunc manpage.
- 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 the perllocale manpage.
$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 the perllocale manpage for how to find
out which locales are available in your system.
$loc = setlocale( LC_ALL, "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 for this process.
Identical to assigning a value to the Perl's builtin
$< variable,
see $UID in the perlvar manpage.
- sigaction
-
Detailed signal management. This uses
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
-
siglongjmp() is C-specific: use die in the perlfunc manpage 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.
- sigsetjmp
-
sigsetjmp() is C-specific: use eval {} instead,
see eval in the perlfunc manpage.
- 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 the perlfunc manpage. See also the Math::Trig manpage.
- sinh
-
This is identical to the C function
sinh()
for returning the hyperbolic sine of the numerical argument.
See also the Math::Trig manpage.
- sleep
-
This is identical to Perl's builtin
sleep() function
for suspending the execution of the current for process
for certain number of seconds, see sleep in the perlfunc manpage.
- sprintf
-
This is similar to Perl's builtin
sprintf() function
for returning a string that has the arguments formatted as requested,
see sprintf in the perlfunc manpage.
- sqrt
-
This is identical to Perl's builtin
sqrt() function.
for returning the square root of the numerical argument,
see sqrt in the perlfunc manpage.
- srand
-
Give a seed the pseudorandom number generator, see srand in the perlfunc manpage.
- sscanf
-
sscanf() is C-specific, use regular expressions instead,
see the perlre manpage.
- stat
-
This is identical to Perl's builtin
stat() function
for retutning information about files and directories.
- strcat
-
strcat() is C-specific, use .= instead, see the perlop manpage.
- strchr
-
strchr() is C-specific, see index in the perlfunc manpage instead.
- strcmp
-
strcmp() is C-specific, use eq or cmp instead, see the perlop manpage.
- 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 the perllocale manpage.
- strcpy
-
strcpy() is C-specific, use = instead, see the perlop manpage.
- strcspn
-
strcspn() is C-specific, use regular expressions instead,
see the perlre manpage.
- strerror
-
Returns the error string for the specified errno.
Identical to the string form of the
$!, see $ERRNO in the perlvar manpage.
- 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. These are aAbBcdHIjmMpSUwWxXyYZ%.
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 the perlfunc manpage.
- strncat
-
strncat() is C-specific, use .= instead, see the perlop manpage.
- strncmp
-
strncmp() is C-specific, use eq instead, see the perlop manpage.
- strncpy
-
strncpy() is C-specific, use = instead, see the perlop manpage.
- strpbrk
-
strpbrk() is C-specific, use regular expressions instead,
see the perlre manpage.
- strrchr
-
strrchr() is C-specific, see rindex in the perlfunc manpage instead.
- strspn
-
strspn() is C-specific, use regular expressions instead,
see the perlre manpage.
- strstr
-
This is identical to Perl's builtin
index() function,
see index in the perlfunc manpage.
- 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
the perlre manpage, or split in the perlfunc manpage.
- 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
the perllocale manpage.
- sysconf
-
Retrieves values of system configurable variables.
The following will get the machine's clock speed.
$clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );
Returns undef on failure.
- system
-
This is identical to Perl's builtin
system() function, see
system in the perlfunc manpage.
- tan
-
This is identical to the C function
tan(), returning the
tangent of the numerical argument. See also the Math::Trig manpage.
- tanh
-
This is identical to the C function
tanh(), returning the
hyperbolic tangent of the numerical argument. See also the Math::Trig manpage.
- tcdrain
-
This is similar to the C function
tcdrain() for draining
the output queue of its argument stream.
Returns undef on failure.
- tcflow
-
This is similar to the C function
tcflow() for controlling
the flow of its argument stream.
Returns undef on failure.
- tcflush
-
This is similar to the C function
tcflush() for flushing
the I/O buffers of its argumeny stream.
Returns undef on failure.
- tcgetpgrp
-
This is identical to the C function
tcgetpgrp() for returning the
process group identifier of the foreground process group of the controlling
terminal.
- tcsendbreak
-
This is similar to the C function
tcsendbreak() for sending
a break on its argument stream.
Returns undef on failure.
- tcsetpgrp
-
This is similar to the C function
tcsetpgrp() for setting the
process group identifier of the foreground process group of the controlling
terminal.
Returns undef on failure.
- time
-
This is identical to Perl's builtin
time() function
for returning the number of seconds since the epoch
(whatever it is for the system), see time in the perlfunc manpage.
- times
-
The
times() function returns elapsed realtime since some point in the past
(such as system startup), user and system times for this process, and user
and system times used by child processes. All times are returned in clock
ticks.
($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 the File::Temp manpage.
- tmpnam
-
Returns a name for a temporary file.
$tmpfile = POSIX::tmpnam();
For security reasons, which are probably detailed in your system's
documentation for the C library tmpnam() function, this interface
should not be used; instead see the File::Temp manpage.
- tolower
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using the
lc() function,
see lc in the perlfunc manpage, or the equivalent \L operator inside doublequotish
strings.
- toupper
-
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using the
uc() function,
see uc in the perlfunc manpage, or the equivalent \U operator inside doublequotish
strings.
- ttyname
-
This is identical to the C function
ttyname() for returning the
name of the current terminal.
- tzname
-
Retrieves the time conversion information from the
tzname variable.
POSIX::tzset();
($std, $dst) = POSIX::tzname();
- tzset
-
This is identical to the C function
tzset() for setting
the current timezone based on the environment variable TZ,
to be used by ctime(), localtime(), mktime(), and strftime()
functions.
- umask
-
This is identical to Perl's builtin
umask() function
for setting (and querying) the file creation permission mask,
see umask in the perlfunc manpage.
- uname
-
Get name of current operating system.
($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 the perlfunc manpage.
- utime
-
This is identical to Perl's builtin
utime() function
for changing the time stamps of files and directories,
see utime in the perlfunc manpage.
- vfprintf
-
vfprintf() is C-specific, see printf in the perlfunc manpage instead.
- vprintf
-
vprintf() is C-specific, see printf in the perlfunc manpage instead.
- vsprintf
-
vsprintf() is C-specific, see sprintf in the perlfunc manpage instead.
- wait
-
This is identical to Perl's builtin
wait() function,
see wait in the perlfunc manpage.
- waitpid
-
Wait for a child process to change state. This is identical to Perl's
builtin
waitpid() function, see waitpid in the perlfunc manpage.
$pid = POSIX::waitpid( -1, &POSIX::WNOHANG );
print "status = ", ($? / 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( $b, $buf, 5 );
Returns undef on failure.
See also syswrite in the perlfunc manpage.
- 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 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.
- 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";
}
- 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()
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
- 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
- Constants
-
_POSIX_ARG_MAX _POSIX_CHILD_MAX _POSIX_CHOWN_RESTRICTED _POSIX_JOB_CONTROL _POSIX_LINK_MAX _POSIX_MAX_CANON _POSIX_MAX_INPUT _POSIX_N
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