perl核心模块解析（一）POSIX

perl核心模块解析（一）    POSIX

详细文档链接如下

源自：http://blog.csdn.net/jonathanxqs

转自：http://perldoc.perl.org/POSIX.html

POSIX/?p?z?ks/,
是可移植操作系统接口（Portable
Operating System Interface ），POSIX标准定义了操作系统应该为应用程序提供的接口标准，是IEEE为要在各种UNIX操作系统上运行的软件而定义的一系列API标准的总称，其正式称呼为IEEE 1003，而国际标准名称为ISO/IEC 9945。

POSIX标准意在期望获得源代码级别的软件可移植性。换句话说，为一个POSIX兼容的操作系统编写的程序，应该可以在任何其它的POSIX操作系统（即使是来自另一个厂商）上编译执行。

POSIX 并不局限于 UNIX。许多其它的操作系统，例如 DEC OpenVMS 支持 POSIX 标准，尤其是 IEEE Std. 1003.1-1990（1995 年修订）或 POSIX.1，POSIX.1 提供了源代码级别的 C 语言应用编程接口（API）给操作系统的服务程序，例如读写文件。POSIX.1 已经被国际标准化组织（International Standards Organization，ISO）所接受，被命名为 ISO/IEC
9945-1:1990 标准。

POSIX

NAME

POSIX - Perl interface to IEEE Std 1003.1

SYNOPSIS

    

  1. use POSIX ();
    2. 

  2. use POSIX qw(setsid);
    3. 

  3. use POSIX qw(:errno_h :fcntl_h);
    4. 

  4. printf "EINTR is %d\n", EINTR;
    5. 

  5. $sess_id = POSIX::setsid();
    6. 

  6. $fd = POSIX::open($path, O_CREAT|O_EXCL|O_WRONLY, 0644);
    7. 

  7. # note: that‘s a filedescriptor, *NOT* a filehandle
    8.

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.

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.

CAVEATS

Everything is exported by default (with a handful of exceptions). This is an unfortunate backwards compatibility feature and its use is strongly discouraged.
You should either prevent the exporting (by saying use POSIX (); ,
as usual) and then use fully qualified names (e.g. POSIX::SEEK_END ), or give an explicit import
list. If you do neither and opt for the default (as in use POSIX; ),
you will import hundreds and hundreds of symbols into your namespace.

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.

      

    1. if( POSIX::access( "/", &POSIX::R_OK ) ){
      2. 

    2. print "have read permission\n";
      3. 

    3. }
      4.

    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 alsoMath::Trig.
  • acosh

    This is identical to the C function acosh() ,
    returning the hyperbolic arcus cosine of its numerical argument [C99]. 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

      

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

    and it is called thusly

      

    1. $asctime = asctime($sec, $min, $hour, $mday, $mon,
      2. 

    2. $year, $wday, $yday, $isdst);
      3.

    The $mon is zero-based: January equals 0 .
    The $year is 1900-based: 2001 equals 101 . $wday and $ydaydefault
    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 alsoMath::Trig.
  • asinh

    This is identical to the C function asinh() ,
    returning the hyperbolic arcus sine of its numerical argument [C99]. See also Math::Trig.
  • assert

    Unimplemented, but you can use die 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 alsoMath::Trig.
  • atanh

    This is identical to the C function atanh() ,
    returning the hyperbolic arcus tangent of its numerical argument [C99]. 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

    Not implemented. atexit() is
    C-specific: use END {} instead, see perlmod.
  • atof

    Not implemented. 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

    Not implemented. 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.
  • atol

    Not implemented. 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.
  • bsearch

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

    Not implemented. calloc() is
    C-specific. Perl does memory management transparently.
  • cbrt

    The cube root [C99].
  • 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, seechdir.
  • chmod

    This is identical to Perl‘s builtin chmod() function,
    allowing one to change file and directory permissions, seechmod.
  • chown

    This is identical to Perl‘s builtin chown() function,
    allowing one to change file and directory owners and groups, see chown.
  • clearerr

    Not implemented. 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 .

      

    1. $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
      2. 

    2. POSIX::close( $fd );
      3.

    Returns undef on
    failure.

    See also close.

  • closedir

    This is identical to Perl‘s builtin closedir() function
    for closing a directory handle, see closedir.
  • cos

    This is identical to Perl‘s builtin cos() function,
    for returning the cosine of its numerical argument, see cos. 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.
  • copysign

    Returns x but with the sign of y [C99].

      

    1. $x_with_sign_of_y = POSIX::copysign($x, $y);
      2.

    See also signbit.

  • creat

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

      

    1. $fd = POSIX::creat( "foo", 0611 );
      2. 

    2. POSIX::close( $fd );
      3.

    See also sysopen and its O_CREAT flag.

  • ctermid

    Generates the path name for the controlling terminal.

      

    1. $path = POSIX::ctermid();
      2.
  • ctime

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

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

      

    1. $name = POSIX::cuserid();
      2.
  • 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

    Not implemented. div() is
    C-specific, use int 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.

  • erf

    The error function [C99].
  • erfc

    The complementary error function [C99].
  • errno

    Returns the value of errno.

      

    1. $errno = POSIX::errno();
      2.

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

  • execl

    Not implemented. execl() is
    C-specific, see exec.
  • execle

    Not implemented. execle() is
    C-specific, see exec.
  • execlp

    Not implemented. execlp() is
    C-specific, see exec.
  • execv

    Not implemented. execv() is
    C-specific, see exec.
  • execve

    Not implemented. execve() is
    C-specific, see exec.
  • execvp

    Not implemented. execvp() is
    C-specific, see exec.
  • exit

    This is identical to Perl‘s builtin exit() function
    for exiting the program, see exit.
  • exp

    This is identical to Perl‘s builtin exp() function
    for returning the exponent (e-based) of the numerical argument, see exp.
  • expm1

    Equivalent to exp(x) - 1 ,
    but more precise for small argument values [C99].

    See also log1p.

  • fabs

    This is identical to Perl‘s builtin abs() function
    for returning the absolute value of the numerical argument, seeabs.
  • fclose

    Not implemented. Use method IO::Handle::close() instead,
    or see close.
  • fcntl

    This is identical to Perl‘s builtin fcntl() function,
    see fcntl.
  • fdopen

    Not implemented. Use method IO::Handle::new_from_fd() instead,
    or see open.
  • feof

    Not implemented. Use method IO::Handle::eof() instead,
    or see eof.
  • ferror

    Not implemented. Use method IO::Handle::error() instead.
  • fflush

    Not implemented. Use method IO::Handle::flush() instead.
    See also $OUTPUT_AUTOFLUSH in perlvar.
  • fgetc

    Not implemented. Use method IO::Handle::getc() instead,
    or see read.
  • fgetpos

    Not implemented. Use method IO::Seekable::getpos() instead,
    or see seek.
  • fgets

    Not implemented. Use method IO::Handle::gets() instead.
    Similar to <>, also known as readline.
  • fileno

    Not implemented. Use method IO::Handle::fileno() instead,
    or see fileno.
  • floor

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

    "Positive difference", x - y if x > y ,
    zero otherwise [C99].
  • fegetround

    Returns the current floating point rounding mode, one of

      

    1. FE_TONEAREST FE_TOWARDZERO FE_UPWARD FE_UPWARD
      2.

    FE_TONEAREST is like round, FE_TOWARDZERO is
    like trunc [C99].

  • fesetround

    Sets the floating point rounding mode, see fegetround.
  • fma

    "Fused multiply-add", x * y + z , possibly
    faster (and less lossy) than the explicit two operations [C99].

      

    1. my $fused = POSIX::fma($x, $y, $z);
      2.
  • fmax

    Maximum of x and y,
    except when either is NaN , returns the other [C99].

      

    1. my $min = POSIX::fmax($x, $y);
      2.
  • fmin

    Minimum of x and y,
    except when either is NaN , returns the other [C99].

      

    1. my $min = POSIX::fmin($x, $y);
      2.
  • fmod

    This is identical to the C function fmod() .

      

    1. $r = fmod($x, $y);
      2.

    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

    Not implemented. Use method IO::File::open() instead,
    or see open.
  • fork

    This is identical to Perl‘s builtin fork() function
    for duplicating the current process, see fork 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.

      

    1. $fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY );
      2. 

    2. $path_max = POSIX::fpathconf($fd, &POSIX::_PC_PATH_MAX);
      3.

    Returns undef on
    failure.

  • fpclassify

    Returns one of

      

    1. FP_NORMAL FP_ZERO FP_SUBNORMAL FP_INFINITE FP_NAN
      2.

    telling the class of the argument [C99].

  • fprintf

    Not implemented. fprintf() is
    C-specific, see printf instead.
  • fputc

    Not implemented. fputc() is
    C-specific, see print instead.
  • fputs

    Not implemented. fputs() is
    C-specific, see print instead.
  • fread

    Not implemented. fread() is
    C-specific, see read instead.
  • free

    Not implemented. free() is
    C-specific. Perl does memory management transparently.
  • freopen

    Not implemented. freopen() is
    C-specific, see open instead.
  • frexp

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

      

    1. ($mantissa, $exponent) = POSIX::frexp( 1.234e56 );
      2.
  • fscanf

    Not implemented. fscanf() is
    C-specific, use <> and regular expressions instead.
  • fseek

    Not implemented. Use method IO::Seekable::seek() instead,
    or see seek.
  • fsetpos

    Not implemented. Use method IO::Seekable::setpos() instead,
    or seek seek.
  • 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.

      

    1. $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
      2. 

    2. @stats = POSIX::fstat( $fd );
      3.
  • fsync

    Not implemented. Use method IO::Handle::sync() instead.
  • ftell

    Not implemented. Use method IO::Seekable::tell() instead,
    or see tell.
  • fwrite

    Not implemented. fwrite() is
    C-specific, see print instead.
  • getc

    This is identical to Perl‘s builtin getc() function,
    see getc.
  • getchar

    Returns one character from STDIN. Identical to Perl‘s getc(),
    see getc.
  • 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 %ENVarray.
  • 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, seegetgrgid.
  • getgrnam

    This is identical to Perl‘s builtin getgrnam() function
    for returning group entries by group names, seegetgrnam.
  • 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.
  • getpgrp

    This is identical to Perl‘s builtin getpgrp() function
    for returning the process group identifier of the current process, see getpgrp.
  • 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.
  • getpwnam

    This is identical to Perl‘s builtin getpwnam() function
    for returning user entries by user names, see getpwnam.
  • getpwuid

    This is identical to Perl‘s builtin getpwuid() function
    for returning user entries by user identifiers, see getpwuid.
  • gets

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

    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.
  • hypot

    Equivalent to sqrt(x * x + y
    * y)     except more stable on very large or very small arguments [C99].
  • ilogb

    Integer binary logarithm [C99]

    For example ilogb(20) is
    4, as an integer.

    See also logb.

  • isalnum

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:alnum:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

    You may want to use the /\w/ construct
    instead.

  • isalpha

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:alpha:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

  • isatty

    Returns a boolean indicating whether the specified filehandle is connected to a tty. Similar to the -t operator, see -X.
  • iscntrl

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:cntrl:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

  • isdigit

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:digit:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

    You may want to use the /\d/ construct
    instead.

  • isfinite

    Returns true if the argument is a finite number (that is, not an infinity, or the not-a-number) [C99].

    See also isinf, isnan, and fpclassify.

  • isgraph

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:graph:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

  • isgreater

    (Also isgreaterequal , isless , islessequal , islessgreater , isunordered )

    Floating point comparisons which handle the NaN [C99].

  • isinf

    Returns true if the argument is an infinity (positive or negative) [C99].

    See also isnan, isfinite, and fpclassify.

  • islower

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:lower:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

    Do not use /[a-z]/ unless you don‘t care about the current locale.

  • isnan

    Returns true if the argument is NaN (not-a-number) [C99].

    Note that you cannot test for "NaN -ness" with

      

    1. $x == $x
      2.

    since the NaN is not equivalent to anything, including itself.

    See also nan, isinf, and fpclassify.

  • isnormal

    Returns true if the argument is normal (that is, not a subnormal/denormal, and not an infinity, or a not-a-number) [C99].

    See also isfinite, and fpclassify.

  • isprint

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:print:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

  • ispunct

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:punct:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

  • isspace

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:space:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

    You may want to use the /\s/ construct
    instead.

  • isupper

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:upper:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

    Do not use /[A-Z]/ unless you don‘t care about the current locale.

  • isxdigit

    Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/
    ^ [[:xdigit:]]+ $ /x     , which you should convert to use instead. The function is deprecated because 1) it doesn‘t handle UTF-8 encoded strings properly; and 2) it returns TRUE even
    if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see Character
    set modifiers in perlre     and Which character set modifier is in effect? in perlre).

    The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for
    every byte in the string.

  • j0
  • j1
  • jn
  • y0
  • y1
  • yn

    The Bessel function of the first kind of the order zero.
  • kill

    This is identical to Perl‘s builtin kill() function
    for sending signals to processes (often to terminate them), seekill.
  • labs

    Not implemented. (For returning absolute values of long integers.) labs() is
    C-specific, see abs 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 a 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.

      

    1. POSIX::lchown($uid, $gid, $file_path);
      2.
  • ldexp

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

      

    1. $x_quadrupled = POSIX::ldexp($x, 2);
      2.
  • ldiv

    Not implemented. (For computing dividends of long integers.) ldiv() is
    C-specific, use / and int() instead.
  • lgamma

    The logarithm of the Gamma function [C99].

    See also tgamma.

  • log1p

    Equivalent to log(1 + x) ,
    but more stable results for small argument values [C99].
  • log2

    Logarithm base two [C99].

    See also expm1.

  • logb

    Integer binary logarithm [C99].

    For example logb(20) is
    4, as a floating point number.

    See also ilogb.

  • link

    This is identical to Perl‘s builtin link() function
    for creating hard links into files, see link.
  • localeconv

    Get numeric formatting information. Returns a reference to a hash containing the current underlying locale‘s formatting values. Users of this function should also read perllocale,
    which provides a comprehensive discussion of Perl locale handling, including a section devoted to this function.

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

      

    1. my $loc = POSIX::setlocale( &POSIX::LC_ALL, "de" );
      2. 

    2. print "Locale: \"$loc\"\n";
      3. 

    3. my $lconv = POSIX::localeconv();
      4. 

    4. foreach my $property (qw(
      5. 

    5. decimal_point
      6. 

    6. thousands_sep
      7. 

    7. grouping
      8. 

    8. int_curr_symbol
      9. 

    9. currency_symbol
      10. 

    10. mon_decimal_point
      11. 

    11. mon_thousands_sep
      12. 

    12. mon_grouping
      13. 

    13. positive_sign
      14. 

    14. negative_sign
      15. 

    15. int_frac_digits
      16. 

    16. frac_digits
      17. 

    17. p_cs_precedes
      18. 

    18. p_sep_by_space
      19. 

    19. n_cs_precedes
      20. 

    20. n_sep_by_space
      21. 

    21. p_sign_posn
      22. 

    22. n_sign_posn
      23. 

    23. int_p_cs_precedes
      24. 

    24. int_p_sep_by_space
      25. 

    25. int_n_cs_precedes
      26. 

    26. int_n_sep_by_space
      27. 

    27. int_p_sign_posn
      28. 

    28. int_n_sign_posn
      29. 

    29. ))
      30. 

    30. {
      31. 

    31. printf qq(%s: "%s",\n),
      32. 

    32. $property, $lconv->{$property};
      33. 

    33. }
      34.

    The members whose names begin with int_p_ and int_n_ were
    added by POSIX.1-2008 and are only available on systems that support them.

  • localtime

    This is identical to Perl‘s builtin localtime() function
    for converting seconds since the epoch to a date seelocaltime.
  • log

    This is identical to Perl‘s builtin log() function,
    returning the natural (e-based) logarithm of the numerical argument, see log.
  • log10

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

      

    1. sub log10 { log($_[0]) / log(10) }
      2.

    or

      

    1. sub log10 { log($_[0]) / 2.30258509299405 }
      2.

    or

      

    1. sub log10 { log($_[0]) * 0.434294481903252 }
      2.
  • longjmp

    Not implemented. longjmp() is
    C-specific: use die instead.
  • lseek

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

      

    1. $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
      2. 

    2. $off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET );
      3.

    Returns undef on
    failure.

  • lrint

    Depending on the current floating point rounding mode, rounds the argument either toward nearest (likeround), toward zero (like trunc),
    downward (toward negative infinity), or upward (toward positive infinity) [C99].

    For the rounding mode, see fegetround.

  • lround

    Like round, but as integer, as opposed to floating point [C99].

    See also ceil, floor, trunc.

  • malloc

    Not implemented. malloc() is
    C-specific. Perl does memory management transparently.
  • mblen

    This is identical to the C function mblen() .

    Core Perl does not have any support for the wide and multibyte characters of the C standards, except under UTF-8 locales, so this might be a rather useless function.

    However, Perl supports Unicode, see perluniintro.

  • mbstowcs

    This is identical to the C function mbstowcs() .

    See mblen.

  • mbtowc

    This is identical to the C function mbtowc() .

    See mblen.

  • memchr

    Not implemented. memchr() is
    C-specific, see index instead.
  • memcmp

    Not implemented. memcmp() is
    C-specific, use eq instead, see perlop.
  • memcpy

    Not implemented. memcpy() is
    C-specific, use = , see perlop, or see substr.
  • memmove

    Not implemented. memmove() is
    C-specific, use = , see perlop, or see substr.
  • memset

    Not implemented. memset() is
    C-specific, use x instead, see perlop.
  • mkdir

    This is identical to Perl‘s builtin mkdir() function
    for creating directories, see mkdir.
  • mkfifo

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

      

    1. if (mkfifo($path, $mode)) { ....
      2.

    Returns undef on
    failure. The $mode is similar to the mode of mkdir(),
    see mkdir, though for mkfifo you mustspecify
    the $mode .

  • mktime

    Convert date/time info to a calendar time.

    Synopsis:

      

    1. mktime(sec, min, hour, mday, mon, year, wday = 0,
      2. 

    2. yday = 0, isdst = -1)
      3.

    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.

      

    1. $time_t = POSIX::mktime( 0, 30, 10, 12, 11, 95 );
      2. 

    2. print "Date = ", POSIX::ctime($time_t);
      3.

    Returns undef on
    failure.

  • modf

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

      

    1. ($fractional, $integral) = POSIX::modf( 3.14 );
      2.

    See also round.

  • nan

    Returns not-a-number [C99].

    See also isnan.

  • nearbyint

    Returns the nearest integer to the argument, according to the current rounding mode (see fegetround) [C99].
  • nextafter

    Returns the next representable floating point number after x in the direction of y [C99].

      

    1. my $nextafter = POSIX::nextafter($x, $y);
      2.

    Like nexttoward, but potentially less accurate.

  • nexttoward

    Returns the next representable floating point number after x in the direction of y [C99].

      

    1. my $nexttoward = POSIX::nexttoward($x, $y);
      2.

    Like nextafter, but potentially more accurate.

  • nice

    This is similar to the C function nice() ,
    for changing the scheduling preference of the current process. Positive arguments mean a more polite process, negative values a more needy process. Normal (non-root) user processes can only change towards being more polite.

    Returns undef on
    failure.

  • offsetof

    Not implemented. offsetof() is
    C-specific, you probably want to see pack 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.

      

    1. $fd = POSIX::open( "foo" );
      2.

    Open a file for read and write.

      

    1. $fd = POSIX::open( "foo", &POSIX::O_RDWR );
      2.

    Open a file for write, with truncation.

      

    1. $fd = POSIX::open(
      2. 

    2. "foo", &POSIX::O_WRONLY | &POSIX::O_TRUNC
      3. 

    3. );
      4.

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

      

    1. $fd = POSIX::open(
      2. 

    2. "foo", &POSIX::O_CREAT | &POSIX::O_WRONLY, 0640
      3. 

    3. );
      4.

    Returns undef on
    failure.

    See also sysopen.

  • opendir

    Open a directory for reading.

      

    1. $dir = POSIX::opendir( "/var" );
      2. 

    2. @files = POSIX::readdir( $dir );
      3. 

    3. POSIX::closedir( $dir );
      4.

    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.

      

    1. $path_max = POSIX::pathconf( "/var",
      2. 

    2. &POSIX::_PC_PATH_MAX );
      3.

    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 warnand $ERRNO
    in perlvar    .
  • pipe

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

      

    1. my ($read, $write) = POSIX::pipe();
      2. 

    2. POSIX::write( $write, "hello", 5 );
      3. 

    3. POSIX::read( $read, $buf, 5 );
      4.

    See also pipe.

  • pow

    Computes $x raised to the power $exponent .

      

    1. $ret = POSIX::pow( $x, $exponent );
      2.

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

  • printf

    Formats and prints the specified arguments to STDOUT . See also printf.
  • putc

    Not implemented. putc() is
    C-specific, see print instead.
  • putchar

    Not implemented. putchar() is
    C-specific, see print instead.
  • puts

    Not implemented. puts() is
    C-specific, see print instead.
  • qsort

    Not implemented. qsort() is
    C-specific, see sort instead.
  • raise

    Sends the specified signal to the current process. See also kill and the $$ in $PID
    in perlvar    .
  • rand

    Not implemented. rand() is
    non-portable, see rand 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.

      

    1. $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
      2. 

    2. $bytes = POSIX::read( $fd, $buf, 3 );
      3.

    Returns undef on
    failure.

    See also sysread.

  • readdir

    This is identical to Perl‘s builtin readdir() function
    for reading directory entries, see readdir.
  • realloc

    Not implemented. realloc() is
    C-specific. Perl does memory management transparently.
  • remainder

    Given x and y,
    returns the value x - n*y ,
    where n is the integer closest to x/y.
    [C99]

      

    1. my $remainder = POSIX::remainder($x, $y)
      2.

    See also remquo.

  • remove

    This is identical to Perl‘s builtin unlink() function
    for removing files, see unlink.
  • remquo

    Like remainder but also returns the low-order bits of the quotient (n) [C99]

    (This is quite esoteric interface, mainly used to implement numerical algorithms.)

  • rename

    This is identical to Perl‘s builtin rename() function
    for renaming files, see rename.
  • 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.
  • rint

    Identical to lrint.
  • rmdir

    This is identical to Perl‘s builtin rmdir() function
    for removing (empty) directories, see rmdir.
  • round

    Returns the integer (but still as floating point) nearest to the argument [C99].

    See also ceil, floor, lround, modf,
    and trunc.

  • scalbn

    Returns x * 2**y [C99].

    See also frexp and ldexp.

  • scanf

    Not implemented. 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

    Not implemented. setjmp() is
    C-specific: use eval {} instead,
    see eval.
  • setlocale

    Modifies and queries the program‘s underlying locale. Users of this function should read perllocale, whch provides a comprehensive discussion of Perl locale
    handling, knowledge of which is necessary to properly use this function. It contains a section devoted to this function. The discussion
    here is merely a summary reference for setlocale() .
    Note that Perl itself is almost entirely unaffected by the locale except within the scope of"use locale" .
    (Exceptions are listed in Not within the scope of use locale in perllocale.)

    The following examples assume

      

    1. use POSIX qw(setlocale LC_ALL LC_CTYPE);
      2.

    has been issued.

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

      

    1. $loc = setlocale( LC_ALL, "C" );
      2.

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

      

    1. $loc = setlocale( LC_CTYPE );
      2.

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

      

    1. $loc = setlocale( LC_CTYPE, "" );
      2.

    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.

      

    1. $loc = setlocale( LC_COLLATE, "es_AR.ISO8859-1" );
      2.
  • 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:

      

    1. sigaction(signal, action, oldaction = 0)
      2.

    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:

      

    1. signo       the signal number
      2. 

    2. errno       the error number
      3. 

    3. code        if this is zero or less, the signal was sent by
      4. 

    4. a user process and the uid and pid make sense,
      5. 

    5. otherwise the signal was sent by the kernel
      6.

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

      

    1. pid         the process id generating the signal
      2. 

    2. uid         the uid of the process id generating the signal
      3. 

    3. status      exit value or signal for SIGCHLD
      4. 

    4. band        band event for SIGPOLL
      5.

    A third argument is also passed to the handler, which contains a copy of the raw binary contents of thesiginfo 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 sigactionand
    possibly also siginfo documentation.

  • siglongjmp

    Not implemented. siglongjmp() is
    C-specific: use die instead.
  • signbit

    Returns zero for positive arguments, non-zero for negative arguments [C99].
  • 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:

      

    1. sigpending(sigset)
      2.

    Returns undef on
    failure.

  • sigprocmask

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

    Synopsis:

      

    1. sigprocmask(how, sigset, oldsigset = 0)
      2.

    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

    Not implemented. sigsetjmp() is
    C-specific: use eval {} instead,
    see eval.
  • sigsuspend

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

    Synopsis:

      

    1. sigsuspend(signal_mask)
      2.

    Returns undef on
    failure.

  • sin

    This is identical to Perl‘s builtin sin() function
    for returning the sine of the numerical argument, see sin. See also Math::Trig.
  • sinh

    This is identical to the C function sinh() for
    returning the hyperbolic sine of the numerical argument. See alsoMath::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. 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.
  • sqrt

    This is identical to Perl‘s builtin sqrt() function.
    for returning the square root of the numerical argument, seesqrt.
  • srand

    Give a seed the pseudorandom number generator, see srand.
  • sscanf

    Not implemented. 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

    Not implemented. strcat() is
    C-specific, use .= instead, see perlop.
  • strchr

    Not implemented. strchr() is
    C-specific, see index instead.
  • strcmp

    Not implemented. 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

    Not implemented. strcpy() is
    C-specific, use = instead, see perlop.
  • strcspn

    Not implemented. 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 $! , see $ERRNO
    in perlvar    .
  • strftime

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

    Synopsis:

      

    1. strftime(fmt, sec, min, hour, mday, mon, year,
      2. 

    2. wday = -1, yday = -1, isdst = -1)
      3.

    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, theresults 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‘sstrftime() function,
    except that the isdst value is not affected.

    The string for Tuesday, December 12, 1995.

      

    1. $str = POSIX::strftime( "%A, %B %d, %Y",
      2. 

    2. 0, 0, 0, 12, 11, 95, 2 );
      3. 

    3. print "$str\n";
      4.
  • strlen

    Not implemented. strlen() is
    C-specific, use length() instead,
    see length.
  • strncat

    Not implemented. strncat() is
    C-specific, use .= instead, see perlop.
  • strncmp

    Not implemented. strncmp() is
    C-specific, use eq instead, see perlop.
  • strncpy

    Not implemented. strncpy() is
    C-specific, use = instead, see perlop.
  • strpbrk

    Not implemented. strpbrk() is
    C-specific, use regular expressions instead, see perlre.
  • strrchr

    Not implemented. strrchr() is
    C-specific, see rindex instead.
  • strspn

    Not implemented. strspn() is
    C-specific, use regular expressions instead, see perlre.
  • strstr

    This is identical to Perl‘s builtin index() function,
    see index.
  • 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 respects any POSIX setlocale() LC_TIME settings,
    regardless of whether or not it is called from Perl code that is within the scope of use locale .

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

      

    1. $! = 0;
      2. 

    2. ($num, $n_unparsed) = POSIX::strtod($str);
      3.

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

      

    1. if (($str eq ‘‘) || ($n_unparsed != 0) || $!) {
      2. 

    2. die "Non-numeric input $str" . ($! ? ": $!\n" : "\n");
      3. 

    3. }
      4.

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

  • strtok

    Not implemented. strtok() is
    C-specific, use regular expressions instead, see perlre, or split.
  • 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

      

    1. $! = 0;
      2. 

    2. ($num, $n_unparsed) = POSIX::strtol($str, $base);
      3.

    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:

      

    1. if (($str eq ‘‘) || ($n_unparsed != 0) || !$!) {
      2. 

    2. die "Non-numeric input $str" . $! ? ": $!\n" : "\n";
      3. 

    3. }
      4.

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

  • strtold

    Like strtod but for long doubles. Defined only if the system supports long doubles.
  • 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 supplystrtoul() parse
    "-1" as a valid value.

  • strxfrm

    String transformation. Returns the transformed string.

      

    1. $dst = POSIX::strxfrm( $src );
      2.

    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.

      

    1. $clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );
      2.

    Returns undef on
    failure.

  • system

    This is identical to Perl‘s builtin system() function,
    see system.
  • tan

    This is identical to the C function tan() ,
    returning the tangent of the numerical argument. See alsoMath::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.

  • tgamma

    The Gamma function [C99].

    See also lgamma.

  • 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.
  • 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.

      

    1. ($realtime, $user, $system, $cuser, $csystem)
      2. 

    2. = POSIX::times();
      3.

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

  • tmpfile

    Not implemented. Use method IO::File::new_tmpfile() instead,
    or see File::Temp.
  • tmpnam

    Returns a name for a temporary file.

      

    1. $tmpfile = POSIX::tmpnam();
      2.

    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, and currently operates as if the locale always is "C". Consider using the lc() function,
    see lc, see lc, or the equivalent \L operator
    inside doublequotish strings.
  • toupper

    This is similar to the C function, except that it can apply to a single character or to a whole string, and currently operates as if the locale always is "C". Consider using the uc() function,
    see uc, or the equivalent \U operator
    inside doublequotish strings.
  • trunc

    Returns the integer toward zero from the argument [C99].

    See also ceil, floor, and round.

  • 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.

      

    1. POSIX::tzset();
      2. 

    2. ($std, $dst) = POSIX::tzname();
      3.
  • tzset

    This is identical to the C function tzset() for
    setting the current timezone based on the environment variableTZ , 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.
  • uname

    Get name of current operating system.

      

    1. ($sysname, $nodename, $release, $version, $machine)
      2. 

    2. = POSIX::uname();
      3.

    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

    Not implemented. Use method IO::Handle::ungetc() instead.
  • unlink

    This is identical to Perl‘s builtin unlink() function
    for removing files, see unlink.
  • utime

    This is identical to Perl‘s builtin utime() function
    for changing the time stamps of files and directories, seeutime.
  • vfprintf

    Not implemented. vfprintf() is
    C-specific, see printf instead.
  • vprintf

    Not implemented. vprintf() is
    C-specific, see printf instead.
  • vsprintf

    Not implemented. vsprintf() is
    C-specific, see sprintf instead.
  • wait

    This is identical to Perl‘s builtin wait() function,
    see wait.
  • waitpid

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

      

    1. $pid = POSIX::waitpid( -1, POSIX::WNOHANG );
      2. 

    2. print "status = ", ($? / 256), "\n";
      3.
  • wcstombs

    This is identical to the C function wcstombs() .

    See mblen.

  • wctomb

    This is identical to the C function wctomb() .

    See mblen.

  • write

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

      

    1. $fd = POSIX::open( "foo", &POSIX::O_WRONLY );
      2. 

    2. $buf = "hello";
      3. 

    3. $bytes = POSIX::write( $fd, $buf, 5 );
      4.

    Returns undef on
    failure.

    See also syswrite.

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 thesa_flags , it defaults to 0.

      

    1. $sigset = POSIX::SigSet->new(SIGINT, SIGQUIT);
      2. 

    2. $sigaction = POSIX::SigAction->new(
      3. 

    3. \&handler, $sigset, &POSIX::SA_NOCLDSTOP
      4. 

    4. );
      5.

    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.

      

    1. $sigset = $sigaction->mask;
      2. 

    2. $sigaction->flags(&POSIX::SA_RESTART);
      3.
  • 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 thePOSIX::SigAction object:

      

    1. $sigaction->safe(1);
      2.

    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() :

      

    1. sigaction(SIGINT, $new_action, $old_action);
      2. 

    2. if ($old_action->safe) {
      3. 

    3. # previous SIGINT handler used safe signals
      4. 

    4. }
      5.

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 existson
    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:

      

    1. sub new {
      2. 

    2. my ($rtsig, $handler, $flags) = @_;
      3. 

    3. my $sigset = POSIX::SigSet($rtsig);
      4. 

    4. my $sigact = POSIX::SigAction->new($handler,$sigset,$flags);
      5. 

    5. sigaction($rtsig, $sigact);
      6. 

    6. }
      7.

    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 $rtsigranges 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.

      

    1. $sigset = POSIX::SigSet->new;
      2.

    Create a set with SIGUSR1 .

      

    1. $sigset = POSIX::SigSet->new( &POSIX::SIGUSR1 );
      2.
  • addset

    Add a signal to a SigSet object.

      

    1. $sigset->addset( &POSIX::SIGUSR2 );
      2.

    Returns undef on
    failure.

  • delset

    Remove a signal from the SigSet object.

      

    1. $sigset->delset( &POSIX::SIGUSR2 );
      2.

    Returns undef on
    failure.

  • emptyset

    Initialize the SigSet object to be empty.

      

    1. $sigset->emptyset();
      2.

    Returns undef on
    failure.

  • fillset

    Initialize the SigSet object to include all signals.

      

    1. $sigset->fillset();
      2.

    Returns undef on
    failure.

  • ismember

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

      

    1. if( $sigset->ismember( &POSIX::SIGUSR1 ) ){
      2. 

    2. print "contains SIGUSR1\n";
      3. 

    3. }
      4.

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.

      

    1. $termios = POSIX::Termios->new;
      2.
  • getattr

    Get terminal control attributes.

    Obtain the attributes for stdin .

      

    1. $termios->getattr( 0 ) # Recommended for clarity.
      2. 

    2. $termios->getattr()
      3.

    Obtain the attributes for stdout.

      

    1. $termios->getattr( 1 )
      2.

    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.

      

    1. $c_cc[1] = $termios->getcc(1);
      2.
  • getcflag

    Retrieve the c_cflag field of a termios object.

      

    1. $c_cflag = $termios->getcflag;
      2.
  • getiflag

    Retrieve the c_iflag field of a termios object.

      

    1. $c_iflag = $termios->getiflag;
      2.
  • getispeed

    Retrieve the input baud rate.

      

    1. $ispeed = $termios->getispeed;
      2.
  • getlflag

    Retrieve the c_lflag field of a termios object.

      

    1. $c_lflag = $termios->getlflag;
      2.
  • getoflag

    Retrieve the c_oflag field of a termios object.

      

    1. $c_oflag = $termios->getoflag;
      2.
  • getospeed

    Retrieve the output baud rate.

      

    1. $ospeed = $termios->getospeed;
      2.
  • setattr

    Set terminal control attributes.

    Set attributes immediately for stdout.

      

    1. $termios->setattr( 1, &POSIX::TCSANOW );
      2.

    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.

      

    1. $termios->setcc( &POSIX::VEOF, 1 );
      2.
  • setcflag

    Set the c_cflag field of a termios object.

      

    1. $termios->setcflag( $c_cflag | &POSIX::CLOCAL );
      2.
  • setiflag

    Set the c_iflag field of a termios object.

      

    1. $termios->setiflag( $c_iflag | &POSIX::BRKINT );
      2.
  • setispeed

    Set the input baud rate.

      

    1. $termios->setispeed( &POSIX::B9600 );
      2.

    Returns undef on
    failure.

  • setlflag

    Set the c_lflag field of a termios object.

      

    1. $termios->setlflag( $c_lflag | &POSIX::ECHO );
      2.
  • setoflag

    Set the c_oflag field of a termios object.

      

    1. $termios->setoflag( $c_oflag | &POSIX::OPOST );
      2.
  • setospeed

    Set the output baud rate.

      

    1. $termios->setospeed( &POSIX::B9600 );
      2.

    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 EBADMSG EBUSY ECANCELEDECHILD ECONNABORTED ECONNREFUSED ECONNRESET EDEADLK EDESTADDRREQ EDOM EDQUOT EEXIST EFAULT EFBIGEHOSTDOWN EHOSTUNREACH EIDRM EILSEQ EINPROGRESS EINTR EINVAL EIO EISCONN EISDIR ELOOP EMFILE EMLINKEMSGSIZE ENAMETOOLONG ENETDOWN ENETRESET ENETUNREACH ENFILE ENOBUFS ENODATA ENODEV ENOENT ENOEXECENOLCK ENOLINK ENOMEM ENOMSG ENOPROTOOPT ENOSPC ENOSR ENOSTR ENOSYS ENOTBLK ENOTCONN ENOTDIRENOTEMPTY ENOTRECOVERABLE ENOTSOCK ENOTSUP ENOTTY ENXIO EOPNOTSUPP EOTHER EOVERFLOW EOWNERDEAD EPERMEPFNOSUPPORT EPIPE EPROCLIM EPROTO EPROTONOSUPPORT EPROTOTYPE ERANGE EREMOTE ERESTART EROFS ESHUTDOWNESOCKTNOSUPPORT ESPIPE ESRCH ESTALE ETIME 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_UNLCKF_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_EXPDBL_MIN_EXP FLT_DIG FLT_EPSILON FLT_MANT_DIG FLT_MAX FLT_MAX_10_EXP FLT_MAX_EXP FLT_MINFLT_MIN_10_EXP FLT_MIN_EXP FLT_RADIX FLT_ROUNDS LDBL_DIG LDBL_EPSILON LDBL_MANT_DIG LDBL_MAXLDBL_MAX_10_EXP LDBL_MAX_EXP LDBL_MIN LDBL_MIN_10_EXP LDBL_MIN_EXP

FLOATING-POINT ENVIRONMENT

  • Constants

    FE_DOWNWARD FE_TONEAREST FE_TOWARDZERO FE_UPWARD on
    systems that support them.

LIMITS

  • Constants

    ARG_MAX CHAR_BIT CHAR_MAX CHAR_MIN CHILD_MAX INT_MAX INT_MIN LINK_MAX LONG_MAX LONG_MIN MAX_CANONMAX_INPUT MB_LEN_MAX NAME_MAX NGROUPS_MAX OPEN_MAX PATH_MAX PIPE_BUF SCHAR_MAX SCHAR_MIN SHRT_MAXSHRT_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 LC_MESSAGES on
    systems that support them.

MATH

  • Constants

    HUGE_VAL

    FP_ILOGB0 FP_ILOGBNAN FP_INFINITE FP_NAN FP_NORMAL FP_SUBNORMAL FP_ZERO INFINITY NAN Inf NaN M_1_PIM_2_PI M_2_SQRTPI M_E M_LN10 M_LN2 M_LOG10E M_LOG2E M_PI M_PI_2 M_PI_4 M_SQRT1_2 M_SQRT2 on
    systems with C99 support.

SIGNAL

  • Constants

    SA_NOCLDSTOP SA_NOCLDWAIT SA_NODEFER SA_ONSTACK SA_RESETHAND SA_RESTART SA_SIGINFO SIGABRT SIGALRMSIGCHLD SIGCONT SIGFPE SIGHUP SIGILL SIGINT SIGKILL SIGPIPE SIGQUIT SIGSEGV SIGSTOP SIGTERM SIGTSTPSIGTTIN 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_IXGRPS_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)

时间： 2024-07-29 00:00:35

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