=head1 NAME POSIX - Perl interface to IEEE Std 1003.1 =head1 SYNOPSIS use POSIX; use POSIX qw(setsid); use POSIX qw(:errno_h :fcntl_h); printf "EINTR is %d\n", EINTR; $sess_id = POSIX::setsid(); $fd = POSIX::open($path, O_CREAT|O_EXCL|O_WRONLY, 0644); # note: that's a filedescriptor, *NOT* a filehandle =head1 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. I with the exception of any POSIX functions with the same name as a built-in Perl function, such as C, C, C, C, etc.., which will be exported only if you ask for them explicitly. This is an unfortunate backwards compatibility feature. You can stop the exporting by saying C and then use the fully qualified names (ie. C). 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 L 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. =head1 NOTE The POSIX module is probably the most complex Perl module supplied with the standard distribution. It incorporates autoloading, namespace games, and dynamic loading of code that's in Perl, C, or both. It's a great source of wisdom. =head1 CAVEATS A few functions are not implemented because they are C specific. If you attempt to call these, they will print a message telling you that they aren't implemented, and suggest using the Perl equivalent should one exist. For example, trying to access the setjmp() call will elicit the message "setjmp() is C-specific: use eval {} instead". Furthermore, some evil vendors will claim 1003.1 compliance, but in fact are not so: they will not pass the PCTS (POSIX Compliance Test Suites). For example, one vendor may not define EDEADLK, or the semantics of the errno values set by open(2) might not be quite right. Perl does not attempt to verify POSIX compliance. That means you can currently successfully say "use POSIX", and then later in your program you find that your vendor has been lax and there's no usable ICANON macro after all. This could be construed to be a bug. =head1 FUNCTIONS =over 8 =item _exit This is identical to the C function C<_exit()>. It exits the program immediately which means among other things buffered I/O is B flushed. Note that when using threads and in Linux this is B 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. =item abort This is identical to the C function C. It terminates the process with a C signal unless caught by a signal handler or if the handler does not return normally (it e.g. does a C). =item abs This is identical to Perl's builtin C function, returning the absolute value of its numerical argument. =item access Determines the accessibility of a file. if( POSIX::access( "/", &POSIX::R_OK ) ){ print "have read permission\n"; } Returns C on failure. Note: do not use C for security purposes. Between the C call and the operation you are preparing for the permissions might change: a classic I. =item acos This is identical to the C function C, returning the arcus cosine of its numerical argument. See also L. =item alarm This is identical to Perl's builtin C function, either for arming or disarming the C timer. =item asctime This is identical to the C function C. 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, $isdst); The C<$mon> is zero-based: January equals C<0>. The C<$year> is 1900-based: 2001 equals C<101>. C<$wday> and C<$yday> default to zero (and are usually ignored anyway), and C<$isdst> defaults to -1. =item asin This is identical to the C function C, returning the arcus sine of its numerical argument. See also L. =item assert Unimplemented, but you can use L and the L module to achieve similar things. =item atan This is identical to the C function C, returning the arcus tangent of its numerical argument. See also L. =item atan2 This is identical to Perl's builtin C function, returning the arcus tangent defined by its two numerical arguments, the I coordinate and the I coordinate. See also L. =item atexit atexit() is C-specific: use C instead, see L. =item 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. =item 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 L. =item 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 L. =item bsearch bsearch() not supplied. For doing binary search on wordlists, see L. =item calloc calloc() is C-specific. Perl does memory management transparently. =item ceil This is identical to the C function C, returning the smallest integer value greater than or equal to the given numerical argument. =item chdir This is identical to Perl's builtin C function, allowing one to change the working (default) directory, see L. =item chmod This is identical to Perl's builtin C function, allowing one to change file and directory permissions, see L. =item chown This is identical to Perl's builtin C function, allowing one to change file and directory owners and groups, see L. =item clearerr Use the method C instead, to reset the error state (if any) and EOF state (if any) of the given stream. =item clock This is identical to the C function C, returning the amount of spent processor time in microseconds. =item close Close the file. This uses file descriptors such as those obtained by calling C. $fd = POSIX::open( "foo", &POSIX::O_RDONLY ); POSIX::close( $fd ); Returns C on failure. See also L. =item closedir This is identical to Perl's builtin C function for closing a directory handle, see L. =item cos This is identical to Perl's builtin C function, for returning the cosine of its numerical argument, see L. See also L. =item cosh This is identical to the C function C, for returning the hyperbolic cosine of its numeric argument. See also L. =item creat Create a new file. This returns a file descriptor like the ones returned by C. Use C to close the file. $fd = POSIX::creat( "foo", 0611 ); POSIX::close( $fd ); See also L and its C flag. =item ctermid Generates the path name for the controlling terminal. $path = POSIX::ctermid(); =item ctime This is identical to the C function C and equivalent to C, see L and L. =item cuserid Get the login name of the owner of the current process. $name = POSIX::cuserid(); =item difftime This is identical to the C function C, for returning the time difference (in seconds) between two times (as returned by C), see L. =item div div() is C-specific, use L on the usual C division and the modulus C<%>. =item dup This is similar to the C function C, for duplicating a file descriptor. This uses file descriptors such as those obtained by calling C. Returns C on failure. =item dup2 This is similar to the C function C, for duplicating a file descriptor to an another known file descriptor. This uses file descriptors such as those obtained by calling C. Returns C on failure. =item errno Returns the value of errno. $errno = POSIX::errno(); This identical to the numerical values of the C<$!>, see L. =item execl execl() is C-specific, see L. =item execle execle() is C-specific, see L. =item execlp execlp() is C-specific, see L. =item execv execv() is C-specific, see L. =item execve execve() is C-specific, see L. =item execvp execvp() is C-specific, see L. =item exit This is identical to Perl's builtin C function for exiting the program, see L. =item exp This is identical to Perl's builtin C function for returning the exponent (I-based) of the numerical argument, see L. =item fabs This is identical to Perl's builtin C function for returning the absolute value of the numerical argument, see L. =item fclose Use method C instead, or see L. =item fcntl This is identical to Perl's builtin C function, see L. =item fdopen Use method C instead, or see L. =item feof Use method C instead, or see L. =item ferror Use method C instead. =item fflush Use method C instead. See also L. =item fgetc Use method C instead, or see L. =item fgetpos Use method C instead, or see L. =item fgets Use method C instead. Similar to EE, also known as L. =item fileno Use method C instead, or see L. =item floor This is identical to the C function C, returning the largest integer value less than or equal to the numerical argument. =item fmod This is identical to the C function C. $r = fmod($x, $y); It returns the remainder C<$r = $x - $n*$y>, where C<$n = trunc($x/$y)>. The C<$r> has the same sign as C<$x> and magnitude (absolute value) less than the magnitude of C<$y>. =item fopen Use method C instead, or see L. =item fork This is identical to Perl's builtin C function for duplicating the current process, see L and L if you are in Windows. =item fpathconf Retrieves the value of a configurable limit on a file or directory. This uses file descriptors such as those obtained by calling C. The following will determine the maximum length of the longest allowable pathname on the filesystem which holds C. $fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY ); $path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX ); Returns C on failure. =item fprintf fprintf() is C-specific, see L instead. =item fputc fputc() is C-specific, see L instead. =item fputs fputs() is C-specific, see L instead. =item fread fread() is C-specific, see L instead. =item free free() is C-specific. Perl does memory management transparently. =item freopen freopen() is C-specific, see L instead. =item frexp Return the mantissa and exponent of a floating-point number. ($mantissa, $exponent) = POSIX::frexp( 1.234e56 ); =item fscanf fscanf() is C-specific, use EE and regular expressions instead. =item fseek Use method C instead, or see L. =item fsetpos Use method C instead, or seek L. =item fstat Get file status. This uses file descriptors such as those obtained by calling C. The data returned is identical to the data from Perl's builtin C function. $fd = POSIX::open( "foo", &POSIX::O_RDONLY ); @stats = POSIX::fstat( $fd ); =item fsync Use method C instead. =item ftell Use method C instead, or see L. =item fwrite fwrite() is C-specific, see L instead. =item getc This is identical to Perl's builtin C function, see L. =item getchar Returns one character from STDIN. Identical to Perl's C, see L. =item getcwd Returns the name of the current working directory. See also L. =item getegid Returns the effective group identifier. Similar to Perl' s builtin variable C<$(>, see L. =item getenv Returns the value of the specified environment variable. The same information is available through the C<%ENV> array. =item geteuid Returns the effective user identifier. Identical to Perl's builtin C<$E> variable, see L. =item getgid Returns the user's real group identifier. Similar to Perl's builtin variable C<$)>, see L. =item getgrgid This is identical to Perl's builtin C function for returning group entries by group identifiers, see L. =item getgrnam This is identical to Perl's builtin C function for returning group entries by group names, see L. =item getgroups Returns the ids of the user's supplementary groups. Similar to Perl's builtin variable C<$)>, see L. =item getlogin This is identical to Perl's builtin C function for returning the user name associated with the current session, see L. =item getpgrp This is identical to Perl's builtin C function for returning the process group identifier of the current process, see L. =item getpid Returns the process identifier. Identical to Perl's builtin variable C<$$>, see L. =item getppid This is identical to Perl's builtin C function for returning the process identifier of the parent process of the current process , see L. =item getpwnam This is identical to Perl's builtin C function for returning user entries by user names, see L. =item getpwuid This is identical to Perl's builtin C function for returning user entries by user identifiers, see L. =item gets Returns one line from C, similar to EE, also known as the C function, see L. B: if you have C programs that still use C, be very afraid. The C function is a source of endless grief because it has no buffer overrun checks. It should B be used. The C function should be preferred instead. =item getuid Returns the user's identifier. Identical to Perl's builtin C<$E> variable, see L. =item gmtime This is identical to Perl's builtin C function for converting seconds since the epoch to a date in Greenwich Mean Time, see L. =item isalnum This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead, or possibly the C construct. =item isalpha This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead. =item isatty Returns a boolean indicating whether the specified filehandle is connected to a tty. Similar to the C<-t> operator, see L. =item iscntrl This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead. =item isdigit This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C (unlikely, but still possible). Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead, or the C construct. =item isgraph This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead. =item islower This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead. Do B use C. =item isprint This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead. =item ispunct This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead. =item isspace This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead, or the C construct. (Note that C and C are slightly different in that C can normally match a vertical tab, while C does not.) =item isupper This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C. Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead. Do B use C. =item isxdigit This is identical to the C function, except that it can apply to a single character or to a whole string. Note that locale settings may affect what characters are considered C (unlikely, but still possible). Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the C construct instead, or simply C. =item kill This is identical to Perl's builtin C function for sending signals to processes (often to terminate them), see L. =item labs (For returning absolute values of long integers.) labs() is C-specific, see L instead. =item ldexp This is identical to the C function C for multiplying floating point numbers with powers of two. $x_quadrupled = POSIX::ldexp($x, 2); =item ldiv (For computing dividends of long integers.) ldiv() is C-specific, use C and C instead. =item link This is identical to Perl's builtin C function for creating hard links into files, see L. =item 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 B (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"; =item localtime This is identical to Perl's builtin C function for converting seconds since the epoch to a date see L. =item log This is identical to Perl's builtin C function, returning the natural (I-based) logarithm of the numerical argument, see L. =item log10 This is identical to the C function C, 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 } =item longjmp longjmp() is C-specific: use L instead. =item lseek Move the file's read/write position. This uses file descriptors such as those obtained by calling C. $fd = POSIX::open( "foo", &POSIX::O_RDONLY ); $off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET ); Returns C on failure. =item malloc malloc() is C-specific. Perl does memory management transparently. =item mblen This is identical to the C function C. Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. =item mbstowcs This is identical to the C function C. Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. =item mbtowc This is identical to the C function C. Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. =item memchr memchr() is C-specific, see L instead. =item memcmp memcmp() is C-specific, use C instead, see L. =item memcpy memcpy() is C-specific, use C<=>, see L, or see L. =item memmove memmove() is C-specific, use C<=>, see L, or see L. =item memset memset() is C-specific, use C instead, see L. =item mkdir This is identical to Perl's builtin C function for creating directories, see L. =item mkfifo This is similar to the C function C for creating FIFO special files. if (mkfifo($path, $mode)) { .... Returns C on failure. The C<$mode> is similar to the mode of C, see L, though for C you B specify the C<$mode>. =item mktime Convert date/time info to a calendar time. Synopsis: mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = -1) The month (C), weekday (C), and yearday (C) begin at zero. I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The year (C) is given in years since 1900. I.e. The year 1995 is 95; the year 2001 is 101. Consult your system's C 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 C on failure. =item modf Return the integral and fractional parts of a floating-point number. ($fractional, $integral) = POSIX::modf( 3.14 ); =item nice This is similar to the C function C, 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 C on failure. =item offsetof offsetof() is C-specific, you probably want to see L instead. =item open Open a file for reading for writing. This returns file descriptors, not Perl filehandles. Use C 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 C on failure. See also L. =item opendir Open a directory for reading. $dir = POSIX::opendir( "/var" ); @files = POSIX::readdir( $dir ); POSIX::closedir( $dir ); Returns C on failure. =item 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 C. $path_max = POSIX::pathconf( "/var", &POSIX::_PC_PATH_MAX ); Returns C on failure. =item pause This is similar to the C function C, which suspends the execution of the current process until a signal is received. Returns C on failure. =item perror This is identical to the C function C, which outputs to the standard error stream the specified message followed by ": " and the current error string. Use the C function and the C<$!> variable instead, see L and L. =item pipe Create an interprocess channel. This returns file descriptors like those returned by C. my ($read, $write) = POSIX::pipe(); POSIX::write( $write, "hello", 5 ); POSIX::read( $read, $buf, 5 ); See also L. =item pow Computes C<$x> raised to the power C<$exponent>. $ret = POSIX::pow( $x, $exponent ); You can also use the C<**> operator, see L. =item printf Formats and prints the specified arguments to STDOUT. See also L. =item putc putc() is C-specific, see L instead. =item putchar putchar() is C-specific, see L instead. =item puts puts() is C-specific, see L instead. =item qsort qsort() is C-specific, see L instead. =item raise Sends the specified signal to the current process. See also L and the C<$$> in L. =item rand C is non-portable, see L instead. =item read Read from a file. This uses file descriptors such as those obtained by calling C. If the buffer C<$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, $buf, 3 ); Returns C on failure. See also L. =item readdir This is identical to Perl's builtin C function for reading directory entries, see L. =item realloc realloc() is C-specific. Perl does memory management transparently. =item remove This is identical to Perl's builtin C function for removing files, see L. =item rename This is identical to Perl's builtin C function for renaming files, see L. =item rewind Seeks to the beginning of the file. =item rewinddir This is identical to Perl's builtin C function for rewinding directory entry streams, see L. =item rmdir This is identical to Perl's builtin C function for removing (empty) directories, see L. =item scanf scanf() is C-specific, use EE and regular expressions instead, see L. =item setgid Sets the real group identifier and the effective group identifier for this process. Similar to assigning a value to the Perl's builtin C<$)> variable, see L, 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. =item setjmp C is C-specific: use C instead, see L. =item 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<"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 C<"">). Please see your systems C documentation for the locale environment variables' meaning or consult L. $loc = setlocale( LC_CTYPE, "" ); The following will set the LC_COLLATE behaviour to Argentinian Spanish. B: The naming and availability of locales depends on your operating system. Please consult L for how to find out which locales are available in your system. $loc = setlocale( LC_ALL, "es_AR.ISO8859-1" ); =item setpgid This is similar to the C function C for setting the process group identifier of the current process. Returns C on failure. =item setsid This is identical to the C function C for setting the session identifier of the current process. =item setuid Sets the real user identifier and the effective user identifier for this process. Similar to assigning a value to the Perl's builtin C<$E> variable, see L, except that the latter will change only the real user identifier. =item sigaction Detailed signal management. This uses C objects for the C and C arguments (the oldaction can also be just a hash reference). Consult your system's C manpage for details, see also C. Synopsis: sigaction(signal, action, oldaction = 0) Returns C on failure. The C must be a number (like SIGHUP), not a string (like "SIGHUP"), though Perl does try hard to understand you. If you use the SA_SIGINFO flag, the signal handler will in addition to the first argument, the signal name, also receive a second argument, a hash reference, inside which are the following keys with the following semantics, as defined by POSIX/SUSv3: signo the signal number errno the error number code if this is zero or less, the signal was sent by a user process and the uid and pid make sense, otherwise the signal was sent by the kernel The following are also defined by POSIX/SUSv3, but unfortunately not very widely implemented: pid the process id generating the signal uid the uid of the process id generating the signal status exit value or signal for SIGCHLD band band event for SIGPOLL A third argument is also passed to the handler, which contains a copy of the raw binary contents of the siginfo structure: if a system has some non-POSIX fields, this third argument is where to unpack() them from. Note that not all siginfo values make sense simultaneously (some are valid only for certain signals, for example), and not all values make sense from Perl perspective, you should to consult your system's C and possibly also C documentation. =item siglongjmp siglongjmp() is C-specific: use L instead. =item sigpending Examine signals that are blocked and pending. This uses C objects for the C argument. Consult your system's C manpage for details. Synopsis: sigpending(sigset) Returns C on failure. =item sigprocmask Change and/or examine calling process's signal mask. This uses C objects for the C and C arguments. Consult your system's C manpage for details. Synopsis: sigprocmask(how, sigset, oldsigset = 0) Returns C on failure. =item sigsetjmp C is C-specific: use C instead, see L. =item sigsuspend Install a signal mask and suspend process until signal arrives. This uses C objects for the C argument. Consult your system's C manpage for details. Synopsis: sigsuspend(signal_mask) Returns C on failure. =item sin This is identical to Perl's builtin C function for returning the sine of the numerical argument, see L. See also L. =item sinh This is identical to the C function C for returning the hyperbolic sine of the numerical argument. See also L. =item sleep This is functionally identical to Perl's builtin C function for suspending the execution of the current for process for certain number of seconds, see L. There is one significant difference, however: C returns the number of B seconds, while the C returns the number of slept seconds. =item sprintf This is similar to Perl's builtin C function for returning a string that has the arguments formatted as requested, see L. =item sqrt This is identical to Perl's builtin C function. for returning the square root of the numerical argument, see L. =item srand Give a seed the pseudorandom number generator, see L. =item sscanf sscanf() is C-specific, use regular expressions instead, see L. =item stat This is identical to Perl's builtin C function for returning information about files and directories. =item strcat strcat() is C-specific, use C<.=> instead, see L. =item strchr strchr() is C-specific, see L instead. =item strcmp strcmp() is C-specific, use C or C instead, see L. =item strcoll This is identical to the C function C for collating (comparing) strings transformed using the C function. Not really needed since Perl can do this transparently, see L. =item strcpy strcpy() is C-specific, use C<=> instead, see L. =item strcspn strcspn() is C-specific, use regular expressions instead, see L. =item strerror Returns the error string for the specified errno. Identical to the string form of the C<$!>, see L. =item 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 (C), weekday (C), and yearday (C) begin at zero. I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The year (C) is given in years since 1900. I.e., the year 1995 is 95; the year 2001 is 101. Consult your system's C manpage for details about these and the other arguments. If you want your code to be portable, your format (C) argument should use only the conversion specifiers defined by the ANSI C standard (C89, to play safe). These are C. But even then, the B of some of the conversion specifiers are non-portable. For example, the specifiers C 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 C 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 C before calling your system's C function, except that the C 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"; =item strlen strlen() is C-specific, use C instead, see L. =item strncat strncat() is C-specific, use C<.=> instead, see L. =item strncmp strncmp() is C-specific, use C instead, see L. =item strncpy strncpy() is C-specific, use C<=> instead, see L. =item strpbrk strpbrk() is C-specific, use regular expressions instead, see L. =item strrchr strrchr() is C-specific, see L instead. =item strspn strspn() is C-specific, use regular expressions instead, see L. =item strstr This is identical to Perl's builtin C function, see L. =item 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 I 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. =item strtok strtok() is C-specific, use regular expressions instead, see L, or L. =item 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 I 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. =item strtoul String to unsigned (long) integer translation. strtoul() is identical to strtol() except that strtoul() only parses unsigned integers. See L for details. Note: Some vendors supply strtod() and strtol() but not strtoul(). Other vendors that do supply strtoul() parse "-1" as a valid value. =item strxfrm String transformation. Returns the transformed string. $dst = POSIX::strxfrm( $src ); Used in conjunction with the C function, see L. Not really needed since Perl can do this transparently, see L. =item sysconf Retrieves values of system configurable variables. The following will get the machine's clock speed. $clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK ); Returns C on failure. =item system This is identical to Perl's builtin C function, see L. =item tan This is identical to the C function C, returning the tangent of the numerical argument. See also L. =item tanh This is identical to the C function C, returning the hyperbolic tangent of the numerical argument. See also L. =item tcdrain This is similar to the C function C for draining the output queue of its argument stream. Returns C on failure. =item tcflow This is similar to the C function C for controlling the flow of its argument stream. Returns C on failure. =item tcflush This is similar to the C function C for flushing the I/O buffers of its argument stream. Returns C on failure. =item tcgetpgrp This is identical to the C function C for returning the process group identifier of the foreground process group of the controlling terminal. =item tcsendbreak This is similar to the C function C for sending a break on its argument stream. Returns C on failure. =item tcsetpgrp This is similar to the C function C for setting the process group identifier of the foreground process group of the controlling terminal. Returns C on failure. =item time This is identical to Perl's builtin C function for returning the number of seconds since the epoch (whatever it is for the system), see L. =item times The times() function returns elapsed realtime since some point in the past (such as system startup), user and system times for this process, and user and system times used by child processes. All times are returned in clock ticks. ($realtime, $user, $system, $cuser, $csystem) = POSIX::times(); Note: Perl's builtin C function returns four values, measured in seconds. =item tmpfile Use method C instead, or see L. =item tmpnam Returns a name for a temporary file. $tmpfile = POSIX::tmpnam(); For security reasons, which are probably detailed in your system's documentation for the C library tmpnam() function, this interface should not be used; instead see L. =item tolower This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using the C function, see L, or the equivalent C<\L> operator inside doublequotish strings. =item toupper This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using the C function, see L, or the equivalent C<\U> operator inside doublequotish strings. =item ttyname This is identical to the C function C for returning the name of the current terminal. =item tzname Retrieves the time conversion information from the C variable. POSIX::tzset(); ($std, $dst) = POSIX::tzname(); =item tzset This is identical to the C function C for setting the current timezone based on the environment variable C, to be used by C, C, C, and C functions. =item umask This is identical to Perl's builtin C function for setting (and querying) the file creation permission mask, see L. =item uname Get name of current operating system. ($sysname, $nodename, $release, $version, $machine) = POSIX::uname(); Note that the actual meanings of the various fields are not that well standardized, do not expect any great portability. The C<$sysname> might be the name of the operating system, the C<$nodename> might be the name of the host, the C<$release> might be the (major) release number of the operating system, the C<$version> might be the (minor) release number of the operating system, and the C<$machine> might be a hardware identifier. Maybe. =item ungetc Use method C instead. =item unlink This is identical to Perl's builtin C function for removing files, see L. =item utime This is identical to Perl's builtin C function for changing the time stamps of files and directories, see L. =item vfprintf vfprintf() is C-specific, see L instead. =item vprintf vprintf() is C-specific, see L instead. =item vsprintf vsprintf() is C-specific, see L instead. =item wait This is identical to Perl's builtin C function, see L. =item waitpid Wait for a child process to change state. This is identical to Perl's builtin C function, see L. $pid = POSIX::waitpid( -1, POSIX::WNOHANG ); print "status = ", ($? / 256), "\n"; =item wcstombs This is identical to the C function C. Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. =item wctomb This is identical to the C function C. Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. =item write Write to a file. This uses file descriptors such as those obtained by calling C. $fd = POSIX::open( "foo", &POSIX::O_WRONLY ); $buf = "hello"; $bytes = POSIX::write( $fd, $buf, 5 ); Returns C on failure. See also L. =back =head1 CLASSES =head2 POSIX::SigAction =over 8 =item new Creates a new C object which corresponds to the C C. 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 C object, it defaults to the empty set. The third parameter contains the C, it defaults to 0. $sigset = POSIX::SigSet->new(SIGINT, SIGQUIT); $sigaction = POSIX::SigAction->new( \&handler, $sigset, &POSIX::SA_NOCLDSTOP ); This C object is intended for use with the C function. =back =over 8 =item handler =item mask =item flags accessor functions to get/set the values of a SigAction object. $sigset = $sigaction->mask; $sigaction->flags(&POSIX::SA_RESTART); =item safe accessor function for the "safe signals" flag of a SigAction object; see L for general information on safe (a.k.a. "deferred") signals. If you wish to handle a signal safely, use this accessor to set the "safe" flag in the C object: $sigaction->safe(1); You may also examine the "safe" flag on the output action object which is filled in when given as the third parameter to C: sigaction(SIGINT, $new_action, $old_action); if ($old_action->safe) { # previous SIGINT handler used safe signals } =back =head2 POSIX::SigRt =over 8 =item %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 $SIG{SIGRTMIN}, but the right POSIX moves (see below) are made with the POSIX::SigSet and POSIX::sigaction instead of accessing the %SIG. You can set the %POSIX::SIGRT elements to set the POSIX realtime signal handlers, use C and C on the elements, and use C on the C<%POSIX::SIGRT> to find out how many POSIX realtime signals there are available (SIGRTMAX - SIGRTMIN + 1, the SIGRTMAX is a valid POSIX realtime signal). Setting the %SIGRT elements is equivalent to calling this: sub new { my ($rtsig, $handler, $flags) = @_; my $sigset = POSIX::SigSet($rtsig); my $sigact = POSIX::SigAction->new($handler, $sigset, $flags); sigaction($rtsig, $sigact); } The flags default to zero, if you want something different you can either use C on $POSIX::SigRt::SIGACTION_FLAGS, or you can derive from POSIX::SigRt and define your own C (the tied hash STORE method of the %SIGRT calls C, where the $rtsig ranges from zero to SIGRTMAX - SIGRTMIN + 1). Just as with any signal, you can use sigaction($rtsig, undef, $oa) to retrieve the installed signal handler (or, rather, the signal action). B 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. =item SIGRTMIN Return the minimum POSIX realtime signal number available, or C if no POSIX realtime signals are available. =item SIGRTMAX Return the maximum POSIX realtime signal number available, or C if no POSIX realtime signals are available. =back =head2 POSIX::SigSet =over 8 =item 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 ); =item addset Add a signal to a SigSet object. $sigset->addset( &POSIX::SIGUSR2 ); Returns C on failure. =item delset Remove a signal from the SigSet object. $sigset->delset( &POSIX::SIGUSR2 ); Returns C on failure. =item emptyset Initialize the SigSet object to be empty. $sigset->emptyset(); Returns C on failure. =item fillset Initialize the SigSet object to include all signals. $sigset->fillset(); Returns C on failure. =item ismember Tests the SigSet object to see if it contains a specific signal. if( $sigset->ismember( &POSIX::SIGUSR1 ) ){ print "contains SIGUSR1\n"; } =back =head2 POSIX::Termios =over 8 =item 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; =item getattr Get terminal control attributes. Obtain the attributes for stdin. $termios->getattr( 0 ) # Recommended for clarity. $termios->getattr() Obtain the attributes for stdout. $termios->getattr( 1 ) Returns C on failure. =item 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); =item getcflag Retrieve the c_cflag field of a termios object. $c_cflag = $termios->getcflag; =item getiflag Retrieve the c_iflag field of a termios object. $c_iflag = $termios->getiflag; =item getispeed Retrieve the input baud rate. $ispeed = $termios->getispeed; =item getlflag Retrieve the c_lflag field of a termios object. $c_lflag = $termios->getlflag; =item getoflag Retrieve the c_oflag field of a termios object. $c_oflag = $termios->getoflag; =item getospeed Retrieve the output baud rate. $ospeed = $termios->getospeed; =item setattr Set terminal control attributes. Set attributes immediately for stdout. $termios->setattr( 1, &POSIX::TCSANOW ); Returns C on failure. =item 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 ); =item setcflag Set the c_cflag field of a termios object. $termios->setcflag( $c_cflag | &POSIX::CLOCAL ); =item setiflag Set the c_iflag field of a termios object. $termios->setiflag( $c_iflag | &POSIX::BRKINT ); =item setispeed Set the input baud rate. $termios->setispeed( &POSIX::B9600 ); Returns C on failure. =item setlflag Set the c_lflag field of a termios object. $termios->setlflag( $c_lflag | &POSIX::ECHO ); =item setoflag Set the c_oflag field of a termios object. $termios->setoflag( $c_oflag | &POSIX::OPOST ); =item setospeed Set the output baud rate. $termios->setospeed( &POSIX::B9600 ); Returns C on failure. =item Baud rate values B38400 B75 B200 B134 B300 B1800 B150 B0 B19200 B1200 B9600 B600 B4800 B50 B2400 B110 =item Terminal interface values TCSADRAIN TCSANOW TCOON TCIOFLUSH TCOFLUSH TCION TCIFLUSH TCSAFLUSH TCIOFF TCOOFF =item c_cc field values VEOF VEOL VERASE VINTR VKILL VQUIT VSUSP VSTART VSTOP VMIN VTIME NCCS =item c_cflag field values CLOCAL CREAD CSIZE CS5 CS6 CS7 CS8 CSTOPB HUPCL PARENB PARODD =item c_iflag field values BRKINT ICRNL IGNBRK IGNCR IGNPAR INLCR INPCK ISTRIP IXOFF IXON PARMRK =item c_lflag field values ECHO ECHOE ECHOK ECHONL ICANON IEXTEN ISIG NOFLSH TOSTOP =item c_oflag field values OPOST =back =head1 PATHNAME CONSTANTS =over 8 =item 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 =back =head1 POSIX CONSTANTS =over 8 =item 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 =back =head1 SYSTEM CONFIGURATION =over 8 =item 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 =back =head1 ERRNO =over 8 =item Constants E2BIG EACCES EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF EBUSY ECHILD ECONNABORTED ECONNREFUSED ECONNRESET EDEADLK EDESTADDRREQ EDOM EDQUOT EEXIST EFAULT EFBIG EHOSTDOWN EHOSTUNREACH EINPROGRESS EINTR EINVAL EIO EISCONN EISDIR ELOOP EMFILE EMLINK EMSGSIZE ENAMETOOLONG ENETDOWN ENETRESET ENETUNREACH ENFILE ENOBUFS ENODEV ENOENT ENOEXEC ENOLCK ENOMEM ENOPROTOOPT ENOSPC ENOSYS ENOTBLK ENOTCONN ENOTDIR ENOTEMPTY ENOTSOCK ENOTTY ENXIO EOPNOTSUPP EPERM EPFNOSUPPORT EPIPE EPROCLIM EPROTONOSUPPORT EPROTOTYPE ERANGE EREMOTE ERESTART EROFS ESHUTDOWN ESOCKTNOSUPPORT ESPIPE ESRCH ESTALE ETIMEDOUT ETOOMANYREFS ETXTBSY EUSERS EWOULDBLOCK EXDEV =back =head1 FCNTL =over 8 =item Constants FD_CLOEXEC F_DUPFD F_GETFD F_GETFL F_GETLK F_OK F_RDLCK F_SETFD F_SETFL F_SETLK F_SETLKW F_UNLCK F_WRLCK O_ACCMODE O_APPEND O_CREAT O_EXCL O_NOCTTY O_NONBLOCK O_RDONLY O_RDWR O_TRUNC O_WRONLY =back =head1 FLOAT =over 8 =item Constants DBL_DIG DBL_EPSILON DBL_MANT_DIG DBL_MAX DBL_MAX_10_EXP DBL_MAX_EXP DBL_MIN DBL_MIN_10_EXP DBL_MIN_EXP FLT_DIG FLT_EPSILON FLT_MANT_DIG FLT_MAX FLT_MAX_10_EXP FLT_MAX_EXP FLT_MIN FLT_MIN_10_EXP FLT_MIN_EXP FLT_RADIX FLT_ROUNDS LDBL_DIG LDBL_EPSILON LDBL_MANT_DIG LDBL_MAX LDBL_MAX_10_EXP LDBL_MAX_EXP LDBL_MIN LDBL_MIN_10_EXP LDBL_MIN_EXP =back =head1 LIMITS =over 8 =item Constants ARG_MAX CHAR_BIT CHAR_MAX CHAR_MIN CHILD_MAX INT_MAX INT_MIN LINK_MAX LONG_MAX LONG_MIN MAX_CANON MAX_INPUT MB_LEN_MAX NAME_MAX NGROUPS_MAX OPEN_MAX PATH_MAX PIPE_BUF SCHAR_MAX SCHAR_MIN SHRT_MAX SHRT_MIN SSIZE_MAX STREAM_MAX TZNAME_MAX UCHAR_MAX UINT_MAX ULONG_MAX USHRT_MAX =back =head1 LOCALE =over 8 =item Constants LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME =back =head1 MATH =over 8 =item Constants HUGE_VAL =back =head1 SIGNAL =over 8 =item Constants SA_NOCLDSTOP SA_NOCLDWAIT SA_NODEFER SA_ONSTACK SA_RESETHAND SA_RESTART SA_SIGINFO SIGABRT SIGALRM SIGCHLD SIGCONT SIGFPE SIGHUP SIGILL SIGINT SIGKILL SIGPIPE SIGQUIT SIGSEGV SIGSTOP SIGTERM SIGTSTP SIGTTIN SIGTTOU SIGUSR1 SIGUSR2 SIG_BLOCK SIG_DFL SIG_ERR SIG_IGN SIG_SETMASK SIG_UNBLOCK =back =head1 STAT =over 8 =item Constants S_IRGRP S_IROTH S_IRUSR S_IRWXG S_IRWXO S_IRWXU S_ISGID S_ISUID S_IWGRP S_IWOTH S_IWUSR S_IXGRP S_IXOTH S_IXUSR =item Macros S_ISBLK S_ISCHR S_ISDIR S_ISFIFO S_ISREG =back =head1 STDLIB =over 8 =item Constants EXIT_FAILURE EXIT_SUCCESS MB_CUR_MAX RAND_MAX =back =head1 STDIO =over 8 =item Constants BUFSIZ EOF FILENAME_MAX L_ctermid L_cuserid L_tmpname TMP_MAX =back =head1 TIME =over 8 =item Constants CLK_TCK CLOCKS_PER_SEC =back =head1 UNISTD =over 8 =item Constants R_OK SEEK_CUR SEEK_END SEEK_SET STDIN_FILENO STDOUT_FILENO STDERR_FILENO W_OK X_OK =back =head1 WAIT =over 8 =item Constants WNOHANG WUNTRACED =over 16 =item WNOHANG Do not suspend the calling process until a child process changes state but instead return immediately. =item WUNTRACED Catch stopped child processes. =back =item Macros WIFEXITED WEXITSTATUS WIFSIGNALED WTERMSIG WIFSTOPPED WSTOPSIG =over 16 =item WIFEXITED WIFEXITED($?) returns true if the child process exited normally (C or by falling off the end of C) =item WEXITSTATUS WEXITSTATUS($?) returns the normal exit status of the child process (only meaningful if WIFEXITED($?) is true) =item WIFSIGNALED WIFSIGNALED($?) returns true if the child process terminated because of a signal =item WTERMSIG WTERMSIG($?) returns the signal the child process terminated for (only meaningful if WIFSIGNALED($?) is true) =item WIFSTOPPED WIFSTOPPED($?) returns true if the child process is currently stopped (can happen only if you specified the WUNTRACED flag to waitpid()) =item WSTOPSIG WSTOPSIG($?) returns the signal the child process was stopped for (only meaningful if WIFSTOPPED($?) is true) =back =back