POSIX(X) Perl Programmers Reference Guide POSIX(X) NAME POSIX - Perl interface to IEEE Std 1003.1 SYNOPSIS use POSIX; use POSIX qw(w); use POSIX qw(:errno_h :fcntl_h); printf "EINTR is %d\n", EINTR; $sess_id = POSIX::setsid(); $fd = POSIX::open($path, O_CREAT|O_EXCL|O_WRONLY, 0644); # note: that's a filedescriptor, *NOT* a filehandle DESCRIPTION The POSIX module permits you to access all (or nearly all) the standard POSIX 1003.1 identifiers. Many of these identifiers have been given Perl-ish interfaces. Things which are "#defines" in C, like EINTR or O_NDELAY, are automatically exported into your namespace. All functions are only exported if you ask for them explicitly. Most likely people will prefer to use the fully-qualified func- tion names. This document gives a condensed list of the features available in the POSIX module. Consult your operating system's manpages for general information on most fea- tures. 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 miscel- laneous objects. The remaining sections list various con- stants and macros in an organization which roughly follows IEEE Std 1003.1b-1993. NOTE The POSIX module is probably the most complex Perl module supplied with the standard distribution. It incorporates autoloading, namespace games, and dynamic loading of code that's in Perl, C, or both. It's a great source of wis- dom. 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 sug- gest 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 compli- ance, 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 val- ues set by open(n) 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. 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 han- dler does not return normally (it e.g. does a "longjmp"). abs This is identical to Perl's builtin "abs()" func- tion, returning the absolute value of its numeri- cal argument. access Determines the accessibility of a file. if( POSIX::access( "/", &POSIX::R_OK ) ){ print "have read permission\n"; } Returns "undef" on failure. Note: do not use "access()" for security purposes. Between the "access()" call and the operation you are prepar- ing 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 argu- ment. See also Math::Trig. alarm This is identical to Perl's builtin "alarm()" function, either for arming or disarming the "SIGARLM" timer. asctime This is identical to the C function "asctime()". It returns a string of the form "Fri Jun 2 18:22:13 2000\n\0" and it is called thusly $asctime = asctime($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst); The $mon is zero-based: January equals 0. The $year is 1900-based: 2001 equals 101. The $wday, $yday, and $isdst default to zero (and the first two are usually ignored anyway). asin This is identical to the C function "asin()", returning the arcus sine of its numerical argu- ment. See also Math::Trig. assert Unimplemented, but you can use "die" in perlfunc and the Carp module to achieve similar things. atan This is identical to the C function "atan()", returning the arcus tangent of its numerical argu- ment. See also Math::Trig. atan2 This is identical to Perl's builtin "atan2()" function, returning the arcus tangent defined by its two numerical arguments, the y coordinate and the x coordinate. See also Math::Trig. atexit atexit() is C-specific: use "END {}" instead, see perlsub. atof atof() is C-specific. Perl converts strings to numbers transparently. If you need to force a scalar to a number, add a zero to it. atoi atoi() is C-specific. Perl converts strings to numbers transparently. If you need to force a scalar to a number, add a zero to it. If you need to have just the integer part, see "int" in perl- func. atol atol() is C-specific. Perl converts strings to numbers transparently. If you need to force a scalar to a number, add a zero to it. If you need to have just the integer part, see "int" in perl- func. bsearch bsearch() not supplied. For doing binary search on wordlists, see Search::Dict. calloc calloc() is C-specific. Perl does memory manage- ment transparently. ceil This is identical to the C function "ceil()", returning the smallest integer value greater than or equal to the given numerical argument. chdir This is identical to Perl's builtin "chdir()" function, allowing one to change the working (default) directory, see "chdir" in perlfunc. chmod This is identical to Perl's builtin "chmod()" function, allowing one to change file and direc- tory permissions, see "chmod" in perlfunc. chown This is identical to Perl's builtin "chown()" function, allowing one to change file and direc- tory owners and groups, see "chown" in perlfunc. clearerr Use the method IO::Handle::clearerr() instead, to reset the error state (if any) and EOF state (if any) of the given stream. clock This is identical to the C function "clock()", returning the amount of spent processor time in microseconds. close Close the file. This uses file descriptors such as those obtained by calling "POSIX::open". $fd = POSIX::open( "foo", &POSIX::O_RDONLY ); POSIX::close( $fd ); Returns "undef" on failure. See also "close" in perlfunc. closedir This is identical to Perl's builtin "closedir()" function for closing a directory handle, see "closedir" in perlfunc. cos This is identical to Perl's builtin "cos()" func- tion, for returning the cosine of its numerical argument, see "cos" in perlfunc. See also Math::Trig. cosh This is identical to the C function "cosh()", for returning the hyperbolic cosine of its numeric argument. See also Math::Trig. creat Create a new file. This returns a file descriptor like the ones returned by "POSIX::open". Use "POSIX::close" to close the file. $fd = POSIX::creat( "foo", 0611 ); POSIX::close( $fd ); See also "sysopen" in perlfunc and its "O_CREAT" flag. ctermid Generates the path name for the controlling termi- nal. $path = POSIX::ctermid(); ctime This is identical to the C function "ctime()" and equivalent to "asctime(localtime(...))", see "asc- time" and "localtime". cuserid Get the login name of the owner of the current process. $name = POSIX::cuserid(); difftime This is identical to the C function "difftime()", for returning the time difference (in seconds) between two times (as returned by "time()"), see "time". div div() is C-specific, use "int" in perlfunc on the usual "/" division and the modulus "%". dup This is similar to the C function "dup()", for duplicating a file descriptor. This uses file descriptors such as those obtained by calling "POSIX::open". Returns "undef" on failure. dup2 This is similar to the C function "dup2()", for duplicating a file descriptor to an another known file descriptor. This uses file descriptors such as those obtained by calling "POSIX::open". Returns "undef" on failure. errno Returns the value of errno. $errno = POSIX::errno(); This identical to the numerical values of the $!, see "$ERRNO" in perlvar. execl execl() is C-specific, see "exec" in perlfunc. execle execle() is C-specific, see "exec" in perlfunc. execlp execlp() is C-specific, see "exec" in perlfunc. execv execv() is C-specific, see "exec" in perlfunc. execve execve() is C-specific, see "exec" in perlfunc. execvp execvp() is C-specific, see "exec" in perlfunc. exit This is identical to Perl's builtin "exit()" func- tion for exiting the program, see "exit" in perl- func. exp This is identical to Perl's builtin "exp()" func- tion for returning the exponent (e-based) of the numerical argument, see "exp" in perlfunc. fabs This is identical to Perl's builtin "abs()" func- tion for returning the absolute value of the numerical argument, see "abs" in perlfunc. fclose Use method "IO::Handle::close()" instead, or see "close" in perlfunc. fcntl This is identical to Perl's builtin "fcntl()" function, see "fcntl" in perlfunc. fdopen Use method "IO::Handle::new_from_fd()" instead, or see "open" in perlfunc. feof Use method "IO::Handle::eof()" instead, or see "eof" in perlfunc. ferror Use method "IO::Handle::error()" instead. fflush Use method "IO::Handle::flush()" instead. See also "$OUTPUT_AUTOFLUSH" in perlvar. fgetc Use method "IO::Handle::getc()" instead, or see "read" in perlfunc. fgetpos Use method "IO::Seekable::getpos()" instead, or see "seek" in L. fgets Use method "IO::Handle::gets()" instead. Similar to <>, also known as "readline" in perlfunc. fileno Use method "IO::Handle::fileno()" instead, or see "fileno" in perlfunc. floor This is identical to the C function "floor()", returning the largest integer value less than or equal to the numerical argument. fmod This is identical to the C function "fmod()". $r = modf($x, $y); It returns the remainder "$r = $x - $n*$y", where "$n = trunc($x/$y)". The $r has the same sign as $x and magnitude (absolute value) less than the magnitude of $y. fopen Use method "IO::File::open()" instead, or see "open" in perlfunc. fork This is identical to Perl's builtin "fork()" func- tion for duplicating the current process, see "fork" in perlfunc and perlfork if you are in Win- dows. fpathconf Retrieves the value of a configurable limit on a file or directory. This uses file descriptors such as those obtained by calling "POSIX::open". The following will determine the maximum length of the longest allowable pathname on the filesystem which holds "/tmp/foo". $fd = POSIX::open( "/tmp/foo", &POSIX::O_RDONLY ); $path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX ); Returns "undef" on failure. fprintf fprintf() is C-specific, see "printf" in perlfunc instead. fputc fputc() is C-specific, see "print" in perlfunc instead. fputs fputs() is C-specific, see "print" in perlfunc instead. fread fread() is C-specific, see "read" in perlfunc instead. free free() is C-specific. Perl does memory management transparently. freopen freopen() is C-specific, see "open" in perlfunc instead. frexp Return the mantissa and exponent of a floating- point number. ($mantissa, $exponent) = POSIX::frexp( 1.234e56 ); fscanf fscanf() is C-specific, use <> and regular expres- sions instead. fseek Use method "IO::Seekable::seek()" instead, or see "seek" in perlfunc. fsetpos Use method "IO::Seekable::setpos()" instead, or seek "seek" in perlfunc. fstat Get file status. This uses file descriptors such as those obtained by calling "POSIX::open". The data returned is identical to the data from Perl's builtin "stat" function. $fd = POSIX::open( "foo", &POSIX::O_RDONLY ); @stats = POSIX::fstat( $fd ); ftell Use method "IO::Seekable::tell()" instead, or see "tell" in perlfunc. fwrite fwrite() is C-specific, see "print" in perlfunc instead. getc This is identical to Perl's builtin "getc()" func- tion, see "getc" in perlfunc. getchar Returns one character from STDIN. Identical to Perl's "getc()", see "getc" in perlfunc. getcwd Returns the name of the current working directory. See also Cwd. getegid Returns the effective group identifier. Similar to Perl' s builtin variable $(, see "$EGID" in perlvar. getenv Returns the value of the specified enironment variable. The same information is available through the %ENV array. geteuid Returns the effective user identifier. Identical to Perl's builtin $> variable, see "$EUID" in per- lvar. getgid Returns the user's real group identifier. Similar to Perl's builtin variable $), see "$GID" in perl- var. getgrgid This is identical to Perl's builtin "getgrgid()" function for returning group entries by group identifiers, see "getgrgid" in perlfunc. getgrnam This is identical to Perl's builtin "getgrnam()" function for returning group entries by group names, see "getgrnam" in perlfunc. getgroups Returns the ids of the user's supplementary groups. Similar to Perl's builtin variable $), see "$GID" in perlvar. getlogin This is identical to Perl's builtin "getlogin()" function for returning the user name associated with the current session, see "getlogin" in perl- func. getpgrp This is identical to Perl's builtin "getpgrp()" function for returning the prcess group identifier of the current process, see "getpgrp" in perlfunc. getpid Returns the process identifier. Identical to Perl's builtin variable $$, see "$PID" in perlvar. getppid This is identical to Perl's builtin "getppid()" function for returning the process identifier of the parent process of the current process , see "getppid" in perlfunc. getpwnam This is identical to Perl's builtin "getpwnam()" function for returning user entries by user names, see "getpwnam" in perlfunc. getpwuid This is identical to Perl's builtin "getpwuid()" function for returning user entries by user iden- tifiers, see "getpwuid" in perlfunc. gets Returns one line from "STDIN", similar to <>, also known as the "readline()" function, see "readline" in perlfunc. NOTE: if you have C programs that still use "gets()", be very afraid. The "gets()" function is a source of endless grief because it has no buffer overrun checks. It should never be used. The "fgets()" function should be preferred instead. getuid Returns the user's identifier. Identical to Perl's builtin $< variable, see "$UID" in perlvar. gmtime This is identical to Perl's builtin "gmtime()" function for converting seconds since the epoch to a date in Greenwich Mean Time, see "gmtime" in perlfunc. isalnum This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:isalnum:]]/" construct instead, or possi- bly the "/\w/" construct. isalpha This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:isalpha:]]/" construct instead. isatty Returns a boolean indicating whether the specified filehandle is connected to a tty. Similar to the "-t" operator, see "-X" in perlfunc. iscntrl This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:iscntrl:]]/" construct instead. isdigit This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:isdigit:]]/" construct instead, or the "/\d/" construct. isgraph This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:isgraph:]]/" construct instead. islower This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:islower:]]/" construct instead. Do not use "/a-z/". isprint This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:isprint:]]/" construct instead. ispunct This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:ispunct:]]/" construct instead. isspace This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:isspace:]]/" construct instead, or the "/\s/" construct. isupper This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:isupper:]]/" construct instead. Do not use "/A-Z/". isxdigit This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using regular expressions and the "/[[:isxdigit:]]/" construct instead, or sim- ply "/[0-9a-f]/i". kill This is identical to Perl's builtin "kill()" func- tion for sending signals to processes (often to terminate them), see "kill" in perlfunc. labs (For returning absolute values of long integers.) labs() is C-specific, see "abs" in perlfunc instead. ldexp This is identical to the C function "ldexp()" for multiplying floating point numbers with powers of two. $x_quadrupled = POSIX::ldexp($x, 2); ldiv (For computing dividends of long integers.) ldiv() is C-specific, use "/" and "int()" instead. link This is identical to Perl's builtin "link()" func- tion for creating hard links into files, see "link" in perlfunc. localeconv Get numeric formatting information. Returns a reference to a hash containing the current locale formatting values. Here is how to query the database for the de (Deutsch or German) locale. $loc = POSIX::setlocale( &POSIX::LC_ALL, "de" ); print "Locale = $loc\n"; $lconv = POSIX::localeconv(); print "decimal_point = ", $lconv->{decimal_point}, "\n"; print "thousands_sep = ", $lconv->{thousands_sep}, "\n"; print "grouping = ", $lconv->{grouping}, "\n"; print "int_curr_symbol = ", $lconv->{int_curr_symbol}, "\n"; print "currency_symbol = ", $lconv->{currency_symbol}, "\n"; print "mon_decimal_point = ", $lconv->{mon_decimal_point}, "\n"; print "mon_thousands_sep = ", $lconv->{mon_thousands_sep}, "\n"; print "mon_grouping = ", $lconv->{mon_grouping}, "\n"; print "positive_sign = ", $lconv->{positive_sign}, "\n"; print "negative_sign = ", $lconv->{negative_sign}, "\n"; print "int_frac_digits = ", $lconv->{int_frac_digits}, "\n"; print "frac_digits = ", $lconv->{frac_digits}, "\n"; print "p_cs_precedes = ", $lconv->{p_cs_precedes}, "\n"; print "p_sep_by_space = ", $lconv->{p_sep_by_space}, "\n"; print "n_cs_precedes = ", $lconv->{n_cs_precedes}, "\n"; print "n_sep_by_space = ", $lconv->{n_sep_by_space}, "\n"; print "p_sign_posn = ", $lconv->{p_sign_posn}, "\n"; print "n_sign_posn = ", $lconv->{n_sign_posn}, "\n"; localtime This is identical to Perl's builtin "localtime()" function for converting seconds since the epoch to a date see "localtime" in perlfunc. log This is identical to Perl's builtin "log()" func- tion, returning the natural (e-based) logarithm of the numerical argument, see "log" in perlfunc. log10 This is identical to the C function "log10()", returning the 10-base logarithm of the numerical argument. You can also use sub log10 { log($_[0]) / log(g) } or sub log10 { log($_[0]) / 2.30258509299405 } or sub log10 { log($_[0]) * 0.434294481903252 } longjmp longjmp() is C-specific: use "die" in perlfunc instead. lseek Move the file's read/write position. This uses file descriptors such as those obtained by calling "POSIX::open". $fd = POSIX::open( "foo", &POSIX::O_RDONLY ); $off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET ); Returns "undef" on failure. malloc malloc() is C-specific. Perl does memory manage- ment transparently. mblen This is identical to the C function "mblen()". Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. mbstowcs This is identical to the C function "mbstowcs()". Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. mbtowc This is identical to the C function "mbtowc()". Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. memchr memchr() is C-specific, see "index" in perlfunc instead. memcmp memcmp() is C-specific, use "eq" instead, see per- lop. memcpy memcpy() is C-specific, use "=", see perlop, or see "substr" in perlfunc. memmove memmove() is C-specific, use "=", see perlop, or see "substr" in perlfunc. memset memset() is C-specific, use "x" instead, see per- lop. mkdir This is identical to Perl's builtin "mkdir()" function for creating directories, see "mkdir" in perlfunc. mkfifo This is similar to the C function "mkfifo()" for creating FIFO special files. if (mkfifo($path, $mode)) { .... Returns "undef" on failure. The $mode is similar to the mode of "mkdir()", see "mkdir" in perlfunc. mktime Convert date/time info to a calendar time. Synopsis: mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = 0) The month ("mon"), weekday ("wday"), and yearday ("yday") begin at zero. I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The year ("year") is given in years since 1900. I.e. The year 1995 is 95; the year 2001 is 101. Con- sult your system's "mktime()" manpage for details about these and the other arguments. Calendar time for December 12, 1995, at 10:30 am. $time_t = POSIX::mktime( 0, 30, 10, 12, 11, 95 ); print "Date = ", POSIX::ctime($time_t); Returns "undef" on failure. modf Return the integral and fractional parts of a floating-point number. ($fractional, $integral) = POSIX::modf( 3.14 ); nice This is similar to the C function "nice()", for changing the scheduling preference of the current process. Positive arguments mean more polite pro- cess, negative values more needy process. Normal user processes can only be more polite. Returns "undef" on failure. offsetof offsetof() is C-specific, you probably want to see "pack" in perlfunc instead. open Open a file for reading for writing. This returns file descriptors, not Perl filehandles. Use "POSIX::close" to close the file. Open a file read-only with mode 0666. $fd = POSIX::open( "foo" ); Open a file for read and write. $fd = POSIX::open( "foo", &POSIX::O_RDWR ); Open a file for write, with truncation. $fd = POSIX::open( "foo", &POSIX::O_WRONLY | &POSIX::O_TRUNC ); Create a new file with mode 0640. Set up the file for writing. $fd = POSIX::open( "foo", &POSIX::O_CREAT | &POSIX::O_WRONLY, 0640 ); Returns "undef" on failure. See also "sysopen" in perlfunc. opendir Open a directory for reading. $dir = POSIX::opendir( "/tmp" ); @files = POSIX::readdir( $dir ); POSIX::closedir( $dir ); Returns "undef" on failure. pathconf Retrieves the value of a configurable limit on a file or directory. The following will determine the maximum length of the longest allowable pathname on the filesystem which holds "/tmp". $path_max = POSIX::pathconf( "/tmp", &POSIX::_PC_PATH_MAX ); Returns "undef" on failure. pause This is similar to the C function "pause()", which suspends the execution of the current process until a signal is received. Returns "undef" on failure. perror This is identical to the C function "perror()", which outputs to the standard error stream the specified message followed by ": " and the current error string. Use the "warn()" function and the $! variable instead, see "warn" in perlfunc and "$ERRNO" in perlvar. pipe Create an interprocess channel. This returns file descriptors like those returned by "POSIX::open". ($fd0, $fd1) = POSIX::pipe(); POSIX::write( $fd0, "hello", 5 ); POSIX::read( $fd1, $buf, 5 ); See also "pipe" in perlfunc. pow Computes $x raised to the power $exponent. $ret = POSIX::pow( $x, $exponent ); You can also use the "**" operator, see perlop. printf Formats and prints the specified arguments to STD- OUT. See also "printf" in perlfunc. putc putc() is C-specific, see "print" in perlfunc instead. putchar putchar() is C-specific, see "print" in perlfunc instead. puts puts() is C-specific, see "print" in perlfunc instead. qsort qsort() is C-specific, see "sort" in perlfunc instead. raise Sends the specified signal to the current process. See also "kill" in perlfunc and the $$ in "$PID" in perlvar. rand "rand()" is non-portable, see "rand" in perlfunc instead. read Read from a file. This uses file descriptors such as those obtained by calling "POSIX::open". If the buffer $buf is not large enough for the read then Perl will extend it to make room for the request. $fd = POSIX::open( "foo", &POSIX::O_RDONLY ); $bytes = POSIX::read( $fd, $buf, 3 ); Returns "undef" on failure. See also "sysread" in perlfunc. readdir This is identical to Perl's builtin "readdir()" function for reading directory entries, see "read- dir" in perlfunc. realloc realloc() is C-specific. Perl does memory manage- ment transparently. remove This is identical to Perl's builtin "unlink()" function for removing files, see "unlink" in perl- func. rename This is identical to Perl's builtin "rename()" function for renaming files, see "rename" in perl- func. rewind Seeks to the beginning of the file. rewinddir This is identical to Perl's builtin "rewinddir()" function for rewinding directory entry streams, see "rewinddir" in perlfunc. rmdir This is identical to Perl's builtin "rmdir()" function for removing (empty) directories, see "rmdir" in perlfunc. scanf scanf() is C-specific, use <> and regular expres- sions instead, see perlre. setgid Sets the real group identifier for this process. Identical to assigning a value to the Perl's builtin $) variable, see "$UID" in perlvar. setjmp "setjmp()" is C-specific: use "eval {}" instead, see "eval" in perlfunc. setlocale Modifies and queries program's locale. The fol- lowing examples assume use POSIX qw(setlocale LC_ALL LC_CTYPE); has been issued. The following will set the traditional UNIX system locale behavior (the second argument "C"). $loc = setlocale( LC_ALL, "C" ); The following will query the current LC_CTYPE cat- egory. (No second argument means 'query'.) $loc = setlocale( LC_CTYPE ); The following will set the LC_CTYPE behaviour according to the locale environment variables (the second argument ""). Please see your systems set- locale(e) documentation for the locale environment variables' meaning or consult perllocale. $loc = setlocale( LC_CTYPE, "" ); The following will set the LC_COLLATE behaviour to Argentinian Spanish. NOTE: The naming and avail- ability of locales depends on your operating sys- tem. Please consult perllocale for how to find out which locales are available in your system. $loc = setlocale( LC_ALL, "es_AR.ISO8859-1" ); setpgid This is similar to the C function "setpgid()" for setting the process group identifier of the cur- rent process. Returns "undef" on failure. setsid This is identical to the C function "setsid()" for setting the session identifier of the current pro- cess. setuid Sets the real user identifier for this process. Identical to assigning a value to the Perl's builtin $< variable, see "$UID" in perlvar. sigaction Detailed signal management. This uses "POSIX::SigAction" objects for the "action" and "oldaction" arguments. Consult your system's "sigaction" manpage for details. Synopsis: sigaction(sig, action, oldaction = 0) Returns "undef" on failure. siglongjmp siglongjmp() is C-specific: use "die" in perlfunc instead. sigpending Examine signals that are blocked and pending. This uses "POSIX::SigSet" objects for the "sigset" argument. Consult your system's "sigpending" man- page for details. Synopsis: sigpending(g) Returns "undef" on failure. sigprocmask Change and/or examine calling process's signal mask. This uses "POSIX::SigSet" objects for the "sigset" and "oldsigset" arguments. Consult your system's "sigprocmask" manpage for details. Synopsis: sigprocmask(how, sigset, oldsigset = 0) Returns "undef" on failure. sigsetjmp "sigsetjmp()" is C-specific: use "eval {}" instead, see "eval" in perlfunc. sigsuspend Install a signal mask and suspend process until signal arrives. This uses "POSIX::SigSet" objects for the "signal_mask" argument. Consult your sys- tem's "sigsuspend" manpage for details. Synopsis: sigsuspend(signal_mask) Returns "undef" on failure. sin This is identical to Perl's builtin "sin()" func- tion for returning the sine of the numerical argu- ment, see "sin" in perlfunc. See also Math::Trig. sinh This is identical to the C function "sinh()" for returning the hyperbolic sine of the numerical argument. See also Math::Trig. sleep This is identical to Perl's builtin "sleep()" function for suspending the execution of the cur- rent for process for certain number of seconds, see "sleep" in perlfunc. sprintf This is similar to Perl's builtin "sprintf()" function for returning a string that has the argu- ments formatted as requested, see "sprintf" in perlfunc. sqrt This is identical to Perl's builtin "sqrt()" func- tion. for returning the square root of the numer- ical argument, see "sqrt" in perlfunc. srand Give a seed the pseudorandom number generator, see "srand" in perlfunc. sscanf sscanf() is C-specific, use regular expressions instead, see perlre. stat This is identical to Perl's builtin "stat()" func- tion for retutning information about files and directories. strcat strcat() is C-specific, use ".=" instead, see per- lop. strchr strchr() is C-specific, see "index" in perlfunc instead. strcmp strcmp() is C-specific, use "eq" or "cmp" instead, see perlop. strcoll This is identical to the C function "strcoll()" for collating (comparing) strings transformed using the "strxfrm()" function. Not really needed since Perl can do this transparently, see perllo- cale. strcpy strcpy() is C-specific, use "=" instead, see per- lop. strcspn strcspn() is C-specific, use regular expressions instead, see perlre. strerror Returns the error string for the specified errno. Identical to the string form of the $!, see "$ERRNO" in perlvar. strftime Convert date and time information to string. Returns the string. Synopsis: strftime(fmt, sec, min, hour, mday, mon, year, wday = -1, yday = -1, isdst = -1) The month ("mon"), weekday ("wday"), and yearday ("yday") begin at zero. I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The year ("year") is given in years since 1900. I.e., the year 1995 is 95; the year 2001 is 101. Con- sult your system's "strftime()" manpage for details about these and the other arguments. If you want your code to be portable, your format ("fmt") argument should use only the conversion specifiers defined by the ANSI C standard. These are "aAbBcdHIjmMpSUwWxXyYZ%". The given arguments are made consistent as though by calling "mktime()" before calling your system's "strf- time()" function, except that the "isdst" value is not affected. The string for Tuesday, December 12, 1995. $str = POSIX::strftime( "%A, %B %d, %Y", 0, 0, 0, 12, 11, 95, 2 ); print "$str\n"; strlen strlen() is C-specific, use "length()" instead, see "length" in perlfunc. strncat strncat() is C-specific, use ".=" instead, see perlop. strncmp strncmp() is C-specific, use "eq" instead, see perlop. strncpy strncpy() is C-specific, use "=" instead, see per- lop. strpbrk strpbrk() is C-specific, use regular expressions instead, see perlre. strrchr strrchr() is C-specific, see "rindex" in perlfunc instead. strspn strspn() is C-specific, use regular expressions instead, see perlre. strstr This is identical to Perl's builtin "index()" function, see "index" in perlfunc. strtod String to double translation. Returns the parsed number and the number of characters in the unparsed portion of the string. Truly POSIX-com- pliant systems set $! ($ERRNO) to indicate a translation error, so clear $! before calling str- tod. However, non-POSIX systems may not check for overflow, and therefore will never set $!. strtod should respect any POSIX setlocale() set- tings. To parse a string $str as a floating point number use $! = 0; ($num, $n_unparsed) = POSIX::strtod($str); The second returned item and $! can be used to check for valid input: if (($str eq '') || ($n_unparsed != 0) || !$!) { die "Non-numeric input $str" . $! ? ": $!\n" : "\n"; } When called in a scalar context strtod returns the parsed number. strtok strtok() is C-specific, use regular expressions instead, see perlre, or "split" in perlfunc. strtol String to (long) integer translation. Returns the parsed number and the number of characters in the unparsed portion of the string. Truly POSIX-com- pliant systems set $! ($ERRNO) to indicate a translation error, so clear $! before calling str- tol. However, non-POSIX systems may not check for overflow, and therefore will never set $!. strtol should respect any POSIX setlocale() set- tings. 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 str- tol will use the string itself to determine the base: a leading "0x" or "0X" means hexadecimal; a leading "0" means octal; any other leading charac- ters mean decimal. Thus, "1234" is parsed as a decimal number, "01234" as an octal number, and "0x1234" as a hexadecimal number. The second returned item and $! can be used to check for valid input: if (($str eq '') || ($n_unparsed != 0) || !$!) { die "Non-numeric input $str" . $! ? ": $!\n" : "\n"; } When called in a scalar context strtol returns the parsed number. strtoul String to unsigned (long) integer translation. strtoul() is identical to strtol() except that strtoul() only parses unsigned integers. See "strtol" for details. Note: Some vendors supply strtod() and strtol() but not strtoul(). Other vendors that do supply strtoul() parse "-1" as a valid value. strxfrm String transformation. Returns the transformed string. $dst = POSIX::strxfrm( $src ); Used in conjunction with the "strcoll()" function, see "strcoll". Not really needed since Perl can do this transpar- ently, see perllocale. sysconf Retrieves values of system configurable variables. The following will get the machine's clock speed. $clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK ); Returns "undef" on failure. system This is identical to Perl's builtin "system()" function, see "system" in perlfunc. tan This is identical to the C function "tan()", returning the tangent of the numerical argument. See also Math::Trig. tanh This is identical to the C function "tanh()", returning the hyperbolic tangent of the numerical argument. See also Math::Trig. tcdrain This is similar to the C function "tcdrain()" for draining the output queue of its argument stream. Returns "undef" on failure. tcflow This is similar to the C function "tcflow()" for controlling the flow of its argument stream. Returns "undef" on failure. tcflush This is similar to the C function "tcflush()" for flushing the I/O buffers of its argumeny stream. Returns "undef" on failure. tcgetpgrp This is identical to the C function "tcgetpgrp()" for returning the process group identifier of the foreground process group of the controlling termi- nal. tcsendbreak This is similar to the C function "tcsendbreak()" for sending a break on its argument stream. Returns "undef" on failure. tcsetpgrp This is similar to the C function "tcsetpgrp()" for setting the process group identifier of the foreground process group of the controlling termi- nal. Returns "undef" on failure. time This is identical to Perl's builtin "time()" func- tion for returning the number of seconds since the epoch (whatever it is for the system), see "time" in perlfunc. times The times() function returns elapsed realtime since some point in the past (such as system startup), user and system times for this process, and user and system times used by child processes. All times are returned in clock ticks. ($realtime, $user, $system, $cuser, $csystem) = POSIX::times(); Note: Perl's builtin "times()" function returns four values, measured in seconds. tmpfile Use method "IO::File::new_tmpfile()" instead, or see File::Temp. tmpnam Returns a name for a temporary file. $tmpfile = POSIX::tmpnam(); For security reasons, which are probably detailed in your system's documentation for the C library tmpnam() function, this interface should not be used; instead see File::Temp. tolower This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using the "lc()" function, see "lc" in perlfunc, or the equivalent "\L" operator inside doublequotish strings. toupper This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using the "uc()" function, see "uc" in perlfunc, or the equivalent "\U" operator inside doublequotish strings. ttyname This is identical to the C function "ttyname()" for returning the name of the current terminal. tzname Retrieves the time conversion information from the "tzname" variable. POSIX::tzset(); ($std, $dst) = POSIX::tzname(); tzset This is identical to the C function "tzset()" for setting the current timezone based on the environ- ment variable "TZ", to be used by "ctime()", "localtime()", "mktime()", and "strftime()" func- tions. umask This is identical to Perl's builtin "umask()" function for setting (and querying) the file cre- ation permission mask, see "umask" in perlfunc. uname Get name of current operating system. ($sysname, $nodename, $release, $version, $machine) = POSIX::uname(); Note that the actual meanings of the various fields are not that well standardized, do not expect any great portability. The $sysname might be the name of the operating system, the $nodename might be the name of the host, the $release might be the (major) release number of the operating system, the $version might be the (minor) release number of the operating system, and the $machine might be a hardware identifier. Maybe. ungetc Use method "IO::Handle::ungetc()" instead. unlink This is identical to Perl's builtin "unlink()" function for removing files, see "unlink" in perl- func. utime This is identical to Perl's builtin "utime()" function for changing the time stamps of files and directories, see "utime" in perlfunc. vfprintf vfprintf() is C-specific, see "printf" in perlfunc instead. vprintf vprintf() is C-specific, see "printf" in perlfunc instead. vsprintf vsprintf() is C-specific, see "sprintf" in perl- func instead. wait This is identical to Perl's builtin "wait()" func- tion, see "wait" in perlfunc. waitpid Wait for a child process to change state. This is identical to Perl's builtin "waitpid()" function, see "waitpid" in perlfunc. $pid = POSIX::waitpid( -1, &POSIX::WNOHANG ); print "status = ", ($? / 256), "\n"; wcstombs This is identical to the C function "wcstombs()". Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. wctomb This is identical to the C function "wctomb()". Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function. write Write to a file. This uses file descriptors such as those obtained by calling "POSIX::open". $fd = POSIX::open( "foo", &POSIX::O_WRONLY ); $buf = "hello"; $bytes = POSIX::write( $b, $buf, 5 ); Returns "undef" on failure. See also "syswrite" in perlfunc. CLASSES POSIX::SigAction new Creates a new "POSIX::SigAction" object which cor- responds to the C "struct sigaction". This object will be destroyed automatically when it is no longer needed. The first parameter is the fully- qualified name of a sub which is a signal-handler. The second parameter is a "POSIX::SigSet" object, it defaults to the empty set. The third parameter contains the "sa_flags", it defaults to 0. $sigset = POSIX::SigSet->new(SIGINT, SIGQUIT); $sigaction = POSIX::SigAction->new( 'main::handler', $sigset, &POSIX::SA_NOCLDSTOP ); This "POSIX::SigAction" object should be used with the "POSIX::sigaction()" function. POSIX::SigSet new Create a new SigSet object. This object will be destroyed automatically when it is no longer needed. Arguments may be supplied to initialize the set. Create an empty set. $sigset = POSIX::SigSet->new; Create a set with SIGUSR1. $sigset = POSIX::SigSet->new( &POSIX::SIGUSR1 ); addset Add a signal to a SigSet object. $sigset->addset( &POSIX::SIGUSR2 ); Returns "undef" on failure. delset Remove a signal from the SigSet object. $sigset->delset( &POSIX::SIGUSR2 ); Returns "undef" on failure. emptyset Initialize the SigSet object to be empty. $sigset->emptyset(); Returns "undef" on failure. fillset Initialize the SigSet object to include all sig- nals. $sigset->fillset(); Returns "undef" on failure. ismember Tests the SigSet object to see if it contains a specific signal. if( $sigset->ismember( &POSIX::SIGUSR1 ) ){ print "contains SIGUSR1\n"; } POSIX::Termios new Create a new Termios object. This object will be destroyed automatically when it is no longer needed. A Termios object corresponds to the termios C struct. new() mallocs a new one, getattr() fills it from a file descriptor, and setattr() sets a file descriptor's parameters to match Termios' contents. $termios = POSIX::Termios->new; getattr Get terminal control attributes. Obtain the attributes for stdin. $termios->getattr() Obtain the attributes for stdout. $termios->getattr( 1 ) Returns "undef" on failure. getcc Retrieve a value from the c_cc field of a termios object. The c_cc field is an array so an index must be specified. $c_cc[1] = $termios->getcc(c); getcflag Retrieve the c_cflag field of a termios object. $c_cflag = $termios->getcflag; getiflag Retrieve the c_iflag field of a termios object. $c_iflag = $termios->getiflag; getispeed Retrieve the input baud rate. $ispeed = $termios->getispeed; getlflag Retrieve the c_lflag field of a termios object. $c_lflag = $termios->getlflag; getoflag Retrieve the c_oflag field of a termios object. $c_oflag = $termios->getoflag; getospeed Retrieve the output baud rate. $ospeed = $termios->getospeed; setattr Set terminal control attributes. Set attributes immediately for stdout. $termios->setattr( 1, &POSIX::TCSANOW ); Returns "undef" on failure. setcc Set a value in the c_cc field of a termios object. The c_cc field is an array so an index must be specified. $termios->setcc( &POSIX::VEOF, 1 ); setcflag Set the c_cflag field of a termios object. $termios->setcflag( $c_cflag | &POSIX::CLOCAL ); setiflag Set the c_iflag field of a termios object. $termios->setiflag( $c_iflag | &POSIX::BRKINT ); setispeed Set the input baud rate. $termios->setispeed( &POSIX::B9600 ); Returns "undef" on failure. setlflag Set the c_lflag field of a termios object. $termios->setlflag( $c_lflag | &POSIX::ECHO ); setoflag Set the c_oflag field of a termios object. $termios->setoflag( $c_oflag | &POSIX::OPOST ); setospeed Set the output baud rate. $termios->setospeed( &POSIX::B9600 ); Returns "undef" on failure. Baud rate values B38400 B75 B200 B134 B300 B1800 B150 B0 B19200 B1200 B9600 B600 B4800 B50 B2400 B110 Terminal interface values TCSADRAIN TCSANOW TCOON TCIOFLUSH TCOFLUSH TCION TCIFLUSH TCSAFLUSH TCIOFF TCOOFF c_cc field values VEOF VEOL VERASE VINTR VKILL VQUIT VSUSP VSTART VSTOP VMIN VTIME NCCS c_cflag field values CLOCAL CREAD CSIZE CS5 CS6 CS7 CS8 CSTOPB HUPCL PARENB PARODD c_iflag field values BRKINT ICRNL IGNBRK IGNCR IGNPAR INLCR INPCK ISTRIP IXOFF IXON PARMRK c_lflag field values ECHO ECHOE ECHOK ECHONL ICANON IEXTEN ISIG NOFLSH TOSTOP c_oflag field values OPOST PATHNAME CONSTANTS Constants _PC_CHOWN_RESTRICTED _PC_LINK_MAX _PC_MAX_CANON _PC_MAX_INPUT _PC_NAME_MAX _PC_NO_TRUNC _PC_PATH_MAX _PC_PIPE_BUF _PC_VDISABLE POSIX CONSTANTS Constants _POSIX_ARG_MAX _POSIX_CHILD_MAX _POSIX_CHOWN_RESTRICTED _POSIX_JOB_CONTROL _POSIX_LINK_MAX _POSIX_MAX_CANON _POSIX_MAX_INPUT _POSIX_NAME_MAX _POSIX_NGROUPS_MAX _POSIX_NO_TRUNC _POSIX_OPEN_MAX _POSIX_PATH_MAX _POSIX_PIPE_BUF _POSIX_SAVED_IDS _POSIX_SSIZE_MAX _POSIX_STREAM_MAX _POSIX_TZNAME_MAX _POSIX_VDIS- ABLE _POSIX_VERSION SYSTEM CONFIGURATION Constants _SC_ARG_MAX _SC_CHILD_MAX _SC_CLK_TCK _SC_JOB_CON- TROL _SC_NGROUPS_MAX _SC_OPEN_MAX _SC_SAVED_IDS _SC_STREAM_MAX _SC_TZNAME_MAX _SC_VERSION ERRNO Constants E2BIG EACCES EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF EBUSY ECHILD ECONNABORTED ECONNREFUSED ECONNRESET EDEADLK EDESTADDRREQ EDOM EDQUOT EEXIST EFAULT EFBIG EHOSTDOWN EHOSTUNREACH EINPROGRESS EINTR EINVAL EIO EISCONN EISDIR ELOOP EMFILE EMLINK EMSGSIZE ENAMETOOLONG ENETDOWN ENE- TRESET ENETUNREACH ENFILE ENOBUFS ENODEV ENOENT ENOEXEC ENOLCK ENOMEM ENOPROTOOPT ENOSPC ENOSYS ENOTBLK ENOTCONN ENOTDIR ENOTEMPTY ENOTSOCK ENOTTY ENXIO EOPNOTSUPP EPERM EPFNOSUPPORT EPIPE EPROCLIM EPROTONOSUPPORT EPROTOTYPE ERANGE EREMOTE ERESTART EROFS ESHUTDOWN ESOCKTNOSUPPORT ESPIPE ESRCH ESTALE ETIMEDOUT ETOOMANYREFS ETXTBSY EUSERS EWOULDBLOCK EXDEV FCNTL Constants FD_CLOEXEC F_DUPFD F_GETFD F_GETFL F_GETLK F_OK F_RDLCK F_SETFD F_SETFL F_SETLK F_SETLKW F_UNLCK F_WRLCK O_ACCMODE O_APPEND O_CREAT O_EXCL O_NOCTTY O_NONBLOCK O_RDONLY O_RDWR O_TRUNC O_WRONLY FLOAT Constants DBL_DIG DBL_EPSILON DBL_MANT_DIG DBL_MAX DBL_MAX_10_EXP DBL_MAX_EXP DBL_MIN DBL_MIN_10_EXP DBL_MIN_EXP FLT_DIG FLT_EPSILON FLT_MANT_DIG FLT_MAX FLT_MAX_10_EXP FLT_MAX_EXP FLT_MIN FLT_MIN_10_EXP FLT_MIN_EXP FLT_RADIX FLT_ROUNDS LDBL_DIG LDBL_EPSILON LDBL_MANT_DIG LDBL_MAX LDBL_MAX_10_EXP LDBL_MAX_EXP LDBL_MIN LDBL_MIN_10_EXP LDBL_MIN_EXP LIMITS Constants ARG_MAX CHAR_BIT CHAR_MAX CHAR_MIN CHILD_MAX INT_MAX INT_MIN LINK_MAX LONG_MAX LONG_MIN MAX_CANON MAX_INPUT MB_LEN_MAX NAME_MAX NGROUPS_MAX OPEN_MAX PATH_MAX PIPE_BUF SCHAR_MAX SCHAR_MIN SHRT_MAX SHRT_MIN SSIZE_MAX STREAM_MAX TZNAME_MAX UCHAR_MAX UINT_MAX ULONG_MAX USHRT_MAX LOCALE Constants LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME MATH Constants HUGE_VAL SIGNAL Constants SA_NOCLDSTOP SA_NOCLDWAIT SA_NODEFER SA_ONSTACK SA_RESETHAND SA_RESTART SA_SIGINFO SIGABRT SIGALRM SIGCHLD SIGCONT SIGFPE SIGHUP SIGILL SIGINT SIGKILL SIGPIPE SIGQUIT SIGSEGV SIGSTOP SIGTERM SIGTSTP SIGTTIN SIGTTOU SIGUSR1 SIGUSR2 SIG_BLOCK SIG_DFL SIG_ERR SIG_IGN SIG_SETMASK SIG_UNBLOCK STAT Constants S_IRGRP S_IROTH S_IRUSR S_IRWXG S_IRWXO S_IRWXU S_ISGID S_ISUID S_IWGRP S_IWOTH S_IWUSR S_IXGRP S_IXOTH S_IXUSR Macros S_ISBLK S_ISCHR S_ISDIR S_ISFIFO S_ISREG STDLIB Constants EXIT_FAILURE EXIT_SUCCESS MB_CUR_MAX RAND_MAX STDIO Constants BUFSIZ EOF FILENAME_MAX L_ctermid L_cuserid L_tmp- name TMP_MAX TIME Constants CLK_TCK CLOCKS_PER_SEC UNISTD Constants R_OK SEEK_CUR SEEK_END SEEK_SET STDIN_FILENO STD- OUT_FILENO STDERR_FILENO W_OK X_OK WAIT Constants WNOHANG WUNTRACED Macros WIFEXITED WEXITSTATUS WIFSIGNALED WTERMSIG WIF- STOPPED WSTOPSIG perl v5.6.1 2001-03-03 POSIX(X)