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
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 function names.
This document gives a condensed list of the features available in the POSIX
module. Consult your operating system's manpages for general information on
most features. Consult perlfunc for functions which are noted as being
identical to Perl's builtin functions.
The first section describes POSIX functions from the 1003.1 specification.
The second section describes some classes for signal objects, TTY objects,
and other miscellaneous objects. The remaining sections list various
constants and macros in an organization which roughly follows IEEE Std
1003.1b-1993.
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.
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.
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 handler does not return normally (it e.g. does a "longjmp").
abs
This is identical to Perl's builtin "abs()" function, returning
the absolute value of its numerical argument.
Returns "undef" on failure. Note: do not use "access()" for
security purposes. Between the "access()" call and the operation
you are preparing for the permissions might change: a classic
race condition.
acos
This is identical to the C function "acos()", returning
the arcus cosine of its numerical argument. See also 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
The $mon is zero-based: January equals 0. The $year is
1900-based: 2001 equals 101. The $wday, $yday, and $isdst
default to zero (and the first two are usually ignored anyway).
asin
This is identical to the C function "asin()", returning
the arcus sine of its numerical argument. See also 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 argument. 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 perlfunc.
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 perlfunc.
bsearch
bsearch() not supplied. For doing binary search on wordlists,
see Search::Dict.
calloc
calloc() is C-specific. Perl does memory management transparently.
ceil
This is identical to the C function "ceil()", returning the smallest
integer value greater than or equal to the given numerical argument.
chdir
This is identical to Perl's builtin "chdir()" function, allowing
one to change the working (default) directory, see ``chdir'' in perlfunc.
chmod
This is identical to Perl's builtin "chmod()" function, allowing
one to change file and directory permissions, see ``chmod'' in perlfunc.
chown
This is identical to Perl's builtin "chown()" function, allowing one
to change file and directory 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".
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()" function, 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.
See also ``sysopen'' in perlfunc and its "O_CREAT" flag.
ctermid
Generates the path name for the controlling terminal.
$path = POSIX::ctermid();
ctime
This is identical to the C function "ctime()" and equivalent
to "asctime(localtime(...))", see ``asctime'' and ``localtime''.
cuserid
Get the login name of the owner of the current process.
$name = POSIX::cuserid();
difftime
This is identical to the C function "difftime()", for returning
the time difference (in seconds) between two times (as returned
by "time()"), see ``time''.
div
div() is C-specific, use ``int'' in 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()" function for exiting the
program, see ``exit'' in perlfunc.
exp
This is identical to Perl's builtin "exp()" function for
returning the exponent (e-based) of the numerical argument,
see ``exp'' in perlfunc.
fabs
This is identical to Perl's builtin "abs()" function 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()" function
for duplicating the current process, see ``fork'' in perlfunc
and perlfork if you are in Windows.
fpathconf
Retrieves the value of a configurable limit on a file or directory. This
uses file descriptors such as those obtained by calling "POSIX::open".
The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds "/var/foo".
fscanf() is C-specific, use <> and regular expressions 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.
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()" function,
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 perlvar.
getgid
Returns the user's real group identifier. Similar to Perl's builtin
variable $), see ``$GID'' in perlvar.
getgrgid
This is identical to Perl's builtin "getgrgid()" function for
returning group entries by group identifiers, 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 perlfunc.
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 identifiers, 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 possibly the "/\w/" construct.
isalpha
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using regular expressions and the
"/[[:isalpha:]]/" construct instead.
isatty
Returns a boolean indicating whether the specified filehandle is connected
to a tty. Similar to the "-t" operator, see ``-X'' in 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 simply "/[0-9a-f]/i".
kill
This is identical to Perl's builtin "kill()" function for sending
signals to processes (often to terminate them), see ``kill'' in 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()" function
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.
malloc() is C-specific. Perl does memory management transparently.
mblen
This is identical to the C function "mblen()".
Perl does not have any support for the wide and multibyte
characters of the C standards, so this might be a rather
useless function.
mbstowcs
This is identical to the C function "mbstowcs()".
Perl does not have any support for the wide and multibyte
characters of the C standards, so this might be a rather
useless function.
mbtowc
This is identical to the C function "mbtowc()".
Perl does not have any support for the wide and multibyte
characters of the C standards, so this might be a rather
useless function.
memchr
memchr() is C-specific, see ``index'' in perlfunc instead.
memcmp
memcmp() is C-specific, use "eq" instead, see perlop.
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 perlop.
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.
The month ("mon"), weekday ("wday"), and yearday ("yday") begin at zero.
I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The
year ("year") is given in years since 1900. I.e. The year 1995 is 95; the
year 2001 is 101. Consult your system's "mktime()" manpage for details
about these and the other arguments.
Return the integral and fractional parts of a floating-point number.
($fractional, $integral) = POSIX::modf( 3.14 );
nice
This is similar to the C function "nice()", for changing
the scheduling preference of the current process. Positive
arguments mean more polite process, negative values more
needy process. Normal user processes can only be more polite.
Returns "undef" on failure.
offsetof
offsetof() is C-specific, you probably want to see ``pack'' in perlfunc instead.
open
Open a file for reading for writing. This returns file descriptors, not
Perl filehandles. Use "POSIX::close" to close the file.
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".
Formats and prints the specified arguments to STDOUT.
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.
This is identical to Perl's builtin "readdir()" function
for reading directory entries, see ``readdir'' in perlfunc.
realloc
realloc() is C-specific. Perl does memory management transparently.
remove
This is identical to Perl's builtin "unlink()" function
for removing files, see ``unlink'' in perlfunc.
rename
This is identical to Perl's builtin "rename()" function
for renaming files, see ``rename'' in perlfunc.
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 expressions 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 following examples assume
use POSIX qw(setlocale LC_ALL LC_CTYPE);
has been issued.
The following will set the traditional UNIX system locale behavior
(the second argument "C").
$loc = setlocale( LC_ALL, "C" );
The following will query the current LC_CTYPE category. (No second
argument means 'query'.)
$loc = setlocale( LC_CTYPE );
The following will set the LC_CTYPE behaviour according to the locale
environment variables (the second argument "").
Please see your systems setlocale(3) documentation for the locale
environment variables' meaning or consult perllocale.
$loc = setlocale( LC_CTYPE, "" );
The following will set the LC_COLLATE behaviour to Argentinian
Spanish. NOTE: The naming and availability of locales depends on
your operating system. Please consult 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 current process.
Returns "undef" on failure.
setsid
This is identical to the C function "setsid()" for
setting the session identifier of the current process.
setuid
Sets the real user identifier for this process.
Identical to assigning a value to the Perl's builtin $< variable,
see ``$UID'' in 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"
manpage for details.
Synopsis:
sigpending(sigset)
Returns "undef" on failure.
sigprocmask
Change and/or examine calling process's signal mask. This uses
"POSIX::SigSet" objects for the "sigset" and "oldsigset" arguments.
Consult your system's "sigprocmask" manpage for details.
Synopsis:
sigprocmask(how, sigset, oldsigset = 0)
Returns "undef" on failure.
sigsetjmp
"sigsetjmp()" is C-specific: use "eval {}" instead,
see ``eval'' in perlfunc.
sigsuspend
Install a signal mask and suspend process until signal arrives. This uses
"POSIX::SigSet" objects for the "signal_mask" argument. Consult your
system's "sigsuspend" manpage for details.
Synopsis:
sigsuspend(signal_mask)
Returns "undef" on failure.
sin
This is identical to Perl's builtin "sin()" function
for returning the sine of the numerical argument,
see ``sin'' in 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 current 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 arguments formatted as requested,
see ``sprintf'' in perlfunc.
sqrt
This is identical to Perl's builtin "sqrt()" function.
for returning the square root of the numerical 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()" function
for retutning information about files and directories.
strcat
strcat() is C-specific, use ".=" instead, see perlop.
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 perllocale.
strcpy
strcpy() is C-specific, use "=" instead, see perlop.
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.
The month ("mon"), weekday ("wday"), and yearday ("yday") begin at zero.
I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The
year ("year") is given in years since 1900. I.e., the year 1995 is 95; the
year 2001 is 101. Consult your system's "strftime()" manpage for details
about these and the other arguments.
If you want your code to be portable, your format ("fmt") argument
should use only the conversion specifiers defined by the ANSI C
standard. These are "aAbBcdHIjmMpSUwWxXyYZ%".
The given arguments are made consistent
as though by calling "mktime()" before calling your system's
"strftime()" function, except that the "isdst" value is not affected.
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 perlop.
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-compliant systems set $! ($ERRNO) to indicate a translation
error, so clear $! before calling strtod. However, non-POSIX systems
may not check for overflow, and therefore will never set $!.
strtod should respect any POSIX setlocale() settings.
To parse a string $str as a floating point number use
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-compliant systems set $! ($ERRNO) to indicate a translation
error, so clear $! before calling strtol. However, non-POSIX systems
may not check for overflow, and therefore will never set $!.
strtol should respect any POSIX setlocale() settings.
To parse a string $str as a number in some base $base use
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:
When called in a scalar context strtol returns the parsed number.
strtoul
String to unsigned (long) integer translation. strtoul() is identical
to strtol() except that strtoul() only parses unsigned integers. See
``strtol'' for details.
Note: Some vendors supply strtod() and strtol() but not strtoul().
Other vendors that do supply strtoul() parse ``-1'' as a valid value.
strxfrm
String transformation. Returns the transformed string.
$dst = POSIX::strxfrm( $src );
Used in conjunction with the "strcoll()" function, see ``strcoll''.
Not really needed since Perl can do this transparently, see
perllocale.
sysconf
Retrieves values of system configurable variables.
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
terminal.
tcsendbreak
This is similar to the C function "tcsendbreak()" for sending
a break on its argument stream.
Returns "undef" on failure.
tcsetpgrp
This is similar to the C function "tcsetpgrp()" for setting the
process group identifier of the foreground process group of the controlling
terminal.
Returns "undef" on failure.
time
This is identical to Perl's builtin "time()" function
for returning the number of seconds since the epoch
(whatever it is for the system), see ``time'' in 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.
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 environment variable "TZ",
to be used by "ctime()", "localtime()", "mktime()", and "strftime()"
functions.
umask
This is identical to Perl's builtin "umask()" function
for setting (and querying) the file creation permission mask,
see ``umask'' in perlfunc.
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 perlfunc.
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 perlfunc instead.
wait
This is identical to Perl's builtin "wait()" function,
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.
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".
Creates a new "POSIX::SigAction" object which corresponds to the C
"struct sigaction". This object will be destroyed automatically when it is
no longer needed. The first parameter is the fully-qualified name of a sub
which is a signal-handler. The second parameter is a "POSIX::SigSet"
object, it defaults to the empty set. The third parameter contains the
"sa_flags", it defaults to 0.
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.