=item _exit
-This is identical to the C function C<_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<not> flushed.
=item abort
-This is identical to the C function C<abort()>.
+This is identical to the C function C<abort()>. It terminates the
+process with a C<SIGABRT> signal unless caught by a signal handler or
+if the handler does not return normally (it e.g. does a C<longjmp>).
=item abs
-This is identical to Perl's builtin C<abs()> function.
+This is identical to Perl's builtin C<abs()> function, returning
+the absolute value of its numerical argument.
=item access
print "have read permission\n";
}
-Returns C<undef> on failure.
+Returns C<undef> on failure. Note: do not use C<access()> for
+security purposes. Between the C<access()> call and the operation
+you are preparing for the permissions might change: a classic
+I<race condition>.
=item acos
-This is identical to the C function C<acos()>.
+This is identical to the C function C<acos()>, returning
+the arcus cosine of its numerical argument.
=item alarm
-This is identical to Perl's builtin C<alarm()> function.
+This is identical to Perl's builtin C<alarm()> function,
+either for arming or disarming the C<SIGARLM> timer.
=item asctime
-This is identical to the C function C<asctime()>.
+This is identical to the C function C<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, $isdst);
+
+The C<$mon> is zero-based: January equals C<0>. The C<$year> is
+1900-based: 2001 equals C<101>. The C<$wday>, C<$yday>, and C<$isdst>
+default to zero (and the first two are usually ignored anyway).
=item asin
-This is identical to the C function C<asin()>.
+This is identical to the C function C<asin()>, returning
+the arcus sine of its numerical argument.
=item assert
-Unimplemented.
+Unimplemented, but you can use L<perlfunc/die> and the L<Carp> module
+to achieve similar things.
=item atan
-This is identical to the C function C<atan()>.
+This is identical to the C function C<atan()>, returning the
+arcus tangent of its numerical argument.
=item atan2
-This is identical to Perl's builtin C<atan2()> function.
+This is identical to Perl's builtin C<atan2()> function, returning
+the arcus tangent defined by its two numerical arguments, the I<y>
+coordinate and the I<x> coordinate.
=item atexit
-atexit() is C-specific: use END {} instead.
+atexit() is C-specific: use C<END {}> instead, see L<perlsub>.
=item atof
-atof() is C-specific.
+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.
+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<perlfunc/int>.
=item atol
-atol() is C-specific.
+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<perlfunc/int>.
=item bsearch
-bsearch() not supplied.
+bsearch() not supplied. For doing binary search on wordlists,
+see L<Search::Dict>.
=item calloc
-calloc() is C-specific.
+calloc() is C-specific. Perl does memory management transparently.
=item ceil
-This is identical to the C function C<ceil()>.
+This is identical to the C function C<ceil()>, returning the smallest
+integer value greater than or equal to the given numerical argument.
=item chdir
-This is identical to Perl's builtin C<chdir()> function.
+This is identical to Perl's builtin C<chdir()> function, allowing
+one to change the working (default) directory, see L<perlfunc/chdir>.
=item chmod
-This is identical to Perl's builtin C<chmod()> function.
+This is identical to Perl's builtin C<chmod()> function, allowing
+one to change file and directory permissions, see L<perlfunc/chmod>.
=item chown
-This is identical to Perl's builtin C<chown()> function.
+This is identical to Perl's builtin C<chown()> function, allowing one
+to change file and directory owners and groups, see L<perlfunc/chown>.
=item clearerr
-Use method C<IO::Handle::clearerr()> instead.
+Use the method L<IO::Handle::clearerr()> 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<clock()>.
+This is identical to the C function C<clock()>, returning the
+amount of spent processor time in microseconds.
=item close
Returns C<undef> on failure.
+See also L<perlfunc/close>.
+
=item closedir
-This is identical to Perl's builtin C<closedir()> function.
+This is identical to Perl's builtin C<closedir()> function for closing
+a directory handle, see L<perlfunc/closedir>.
=item cos
-This is identical to Perl's builtin C<cos()> function.
+This is identical to Perl's builtin C<cos()> function, for returning
+the cosine of its numerical argument, see L<perlfunc/cos>.
=item cosh
-This is identical to the C function C<cosh()>.
+This is identical to the C function C<cosh()>, for returning
+the hyperbolic cosine of its numeric argument.
=item creat
$fd = POSIX::creat( "foo", 0611 );
POSIX::close( $fd );
+See also L<perlfunc/sysopen> and its C<O_CREAT> flag.
+
=item ctermid
Generates the path name for the controlling terminal.
=item div
-div() is C-specific.
+div() is C-specific, use L<perlfunc/int> on the usual C</> division and
+the modulus C<%>.
=item dup
$errno = POSIX::errno();
+This identical to the numerical values of the C<$!>, see L<perlvar>.
+
=item execl
-execl() is C-specific.
+execl() is C-specific, see L<perlfunc/exec>.
=item execle
-execle() is C-specific.
+execle() is C-specific, see L<perlfunc/exec>.
=item execlp
-execlp() is C-specific.
+execlp() is C-specific, see L<perlfunc/exec>.
=item execv
-execv() is C-specific.
+execv() is C-specific, see L<perlfunc/exec>.
=item execve
-execve() is C-specific.
+execve() is C-specific, see L<perlfunc/exec>.
=item execvp
-execvp() is C-specific.
+execvp() is C-specific, see L<perlfunc/exec>.
=item exit
-This is identical to Perl's builtin C<exit()> function.
+This is identical to Perl's builtin C<exit()> function for exiting the
+program, see L<perlfunc/exit>.
=item exp
-This is identical to Perl's builtin C<exp()> function.
+This is identical to Perl's builtin C<exp()> function for
+returning the exponent (I<e>-based) of the numerical argument,
+see L<perlfunc/exp>.
=item fabs
-This is identical to Perl's builtin C<abs()> function.
+This is identical to Perl's builtin C<abs()> function for returning
+the absolute value of the numerical argument, see L<perlfunc/abs>.
=item fclose
=item fcntl
-This is identical to Perl's builtin C<fcntl()> function.
+This is identical to Perl's builtin C<fcntl()> function,
+see L<perlfunc/fcntl>.
=item fdopen
=item fgets
-Use method C<IO::Handle::gets()> instead.
+Use method C<IO::Handle::gets()> instead. Similar to <>, also known
+as L<perlfunc/readline>.
=item fileno
=item floor
-This is identical to the C function C<floor()>.
+This is identical to the C function C<floor()>, returning the largest
+integer value less than or equal to the numerical argument.
=item fmod
This is identical to the C function C<fmod()>.
+ $r = modf($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<IO::File::open()> instead.
=item fprintf
-fprintf() is C-specific--use printf instead.
+fprintf() is C-specific, see L<perlfunc/printf> instead.
=item fputc
-fputc() is C-specific--use print instead.
+fputc() is C-specific, see L<perlfunc/print> instead.
=item fputs
-fputs() is C-specific--use print instead.
+fputs() is C-specific, see L<perlfunc/print> instead.
=item fread
-fread() is C-specific--use read instead.
+fread() is C-specific, see L<perlfunc/read> instead.
=item free
-free() is C-specific.
+free() is C-specific. Perl does memory management transparently.
=item freopen
-freopen() is C-specific--use open instead.
+freopen() is C-specific, see L<perlfunc/open> instead.
=item frexp
=item fwrite
-fwrite() is C-specific--use print instead.
+fwrite() is C-specific, see L<perlfunc/print> instead.
=item getc
-This is identical to Perl's builtin C<getc()> function.
+This is identical to Perl's builtin C<getc()> function,
+see L<perlfunc/getc>.
=item getchar
=item getenv
Returns the value of the specified enironment variable.
+The same information is available through the C<%ENV> array.
=item geteuid
=item getgrgid
-This is identical to Perl's builtin C<getgrgid()> function.
+This is identical to Perl's builtin C<getgrgid()> function,
+see L<perlfunc/getgrgid>.
=item getgrnam
-This is identical to Perl's builtin C<getgrnam()> function.
+This is identical to Perl's builtin C<getgrnam()> function,
+see L<perlfunc/getgrnam>.
=item getgroups
=item getlogin
-This is identical to Perl's builtin C<getlogin()> function.
+This is identical to Perl's builtin C<getlogin()> function,
+see L<perlfunc/getlogin>.
=item getpgrp
-This is identical to Perl's builtin C<getpgrp()> function.
+This is identical to Perl's builtin C<getpgrp()> function,
+see L<perlfunc/getpgrp>.
=item getpid
=item getppid
-This is identical to Perl's builtin C<getppid()> function.
+This is identical to Perl's builtin C<getppid()> function,
+see L<perlfunc/getppid>.
=item getpwnam
-This is identical to Perl's builtin C<getpwnam()> function.
+This is identical to Perl's builtin C<getpwnam()> function,
+see L<perlfunc/getpwnam>.
=item getpwuid
-This is identical to Perl's builtin C<getpwuid()> function.
+This is identical to Perl's builtin C<getpwuid()> function,
+see L<perlfunc/getpwuid>.
=item gets
-Returns one line from STDIN.
+Returns one line from C<STDIN>, similar to <>, also known
+as the C<readline()> functions, see L<perlfunc/readline>.
=item getuid
=item gmtime
-This is identical to Perl's builtin C<gmtime()> function.
+This is identical to Perl's builtin C<gmtime()> function,
+see L<perlfunc/gmtime>.
=item isalnum
This is identical to the C function, except that it can apply to a single
-character or to a whole string.
+character or to a whole string. Consider using regular expressions and the
+C</[[:isalnum:]]/> construct instead.
=item isalpha
This is identical to the C function, except that it can apply to a single
-character or to a whole string.
+character or to a whole string. Consider using regular expressions and the
+C</[[:isalpha:]]/> construct instead.
=item isatty
Returns a boolean indicating whether the specified filehandle is connected
-to a tty.
+to a tty. Similar to the C<-t> operator, see L<perlfunc/-X>.
=item iscntrl
This is identical to the C function, except that it can apply to a single
-character or to a whole string.
+character or to a whole string. Consider using regular expressions and the
+C</[[:iscntrl:]]/> 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.
+character or to a whole string. Consider using regular expressions and the
+C</[[:isdigit:]]/> construct instead.
=item isgraph
This is identical to the C function, except that it can apply to a single
-character or to a whole string.
+character or to a whole string. Consider using regular expressions and the
+C</[[:isgraph:]]/> 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.
+character or to a whole string. Consider using regular expressions and the
+C</[[:islower:]]/> construct instead.
=item isprint
This is identical to the C function, except that it can apply to a single
-character or to a whole string.
+character or to a whole string. Consider using regular expressions and the
+C</[[:isprint:]]/> 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.
+character or to a whole string. Consider using regular expressions and the
+C</[[:ispunct:]]/> 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.
+character or to a whole string. Consider using regular expressions and the
+C</[[:isspace:]]/> construct instead.
=item isupper
This is identical to the C function, except that it can apply to a single
-character or to a whole string.
+character or to a whole string. Consider using regular expressions and the
+C</[[:isupper:]]/> construct instead.
=item isxdigit
This is identical to the C function, except that it can apply to a single
-character or to a whole string.
+character or to a whole string. Consider using regular expressions and the
+C</[[:isxdigit:]]/> construct instead.
=item kill
=item labs
-labs() is C-specific, use abs instead.
+labs() is C-specific, see L<perlfunc/abs> instead.
=item ldexp
=item ldiv
-ldiv() is C-specific, use / and int instead.
+ldiv() is C-specific, use C</> and C<int()> instead.
=item link
Get numeric formatting information. Returns a reference to a hash
containing the current locale formatting values.
-The database for the B<de> (Deutsch or German) locale.
+Here is how to query the database for the B<de> (Deutsch or German) locale.
$loc = POSIX::setlocale( &POSIX::LC_ALL, "de" );
print "Locale = $loc\n";
=item log
-This is identical to Perl's builtin C<log()> function.
+This is identical to Perl's builtin C<log()> function,
+returning the natural (I<e>-based) logarithm of the numerical argument,
+see L<perlfunc/log>.
=item log10
-This is identical to the C function C<log10()>.
+This is identical to the C function C<log10()>,
+returning the 10-base logarithm of the numerical argument.
+You can also use
+
+ sub log10 { log($_[0]) / log(10) }
+
+or
+
+ sub log10 { log($_[0]) / 2.30258509299405 }
+
+or
+
+ sub log10 { log($_[0]) * 0.434294481903252 }
=item longjmp
-longjmp() is C-specific: use die instead.
+longjmp() is C-specific: use L<perlfunc/die> instead.
=item lseek
=item malloc
-malloc() is C-specific.
+malloc() is C-specific. Perl does memory management transparently.
=item mblen
=item memchr
-memchr() is C-specific, use index() instead.
+memchr() is C-specific, see L<perlfunc/index> instead.
=item memcmp
-memcmp() is C-specific, use eq instead.
+memcmp() is C-specific, use C<eq> instead, see L<perlop>.
=item memcpy
-memcpy() is C-specific, use = instead.
+memcpy() is C-specific, use C<=>, see L<perlop>, or see L<perlfunc/substr>.
=item memmove
-memmove() is C-specific, use = instead.
+memmove() is C-specific, use C<=>, see L<perlop>, or see L<perlfunc/substr>.
=item memset
-memset() is C-specific, use x instead.
+memset() is C-specific, use C<x> instead, see L<perlop>.
=item mkdir
-This is identical to Perl's builtin C<mkdir()> function.
+This is identical to Perl's builtin C<mkdir()> function
+for creating directories, see L<perlfunc/mkdir>.
=item mkfifo
-This is similar to the C function C<mkfifo()>.
+This is similar to the C function C<mkfifo()> for creating
+FIFO special files.
-Returns C<undef> on failure.
+ if (mkfifo($path, $mode)) { ....
+
+Returns C<undef> on failure. The C<$mode> is similar to the
+mode of C<mkdir()>, see L<perlfunc/mkdir>.
=item mktime
=item nice
-This is similar to the C function C<nice()>.
+This is similar to the C function C<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 C<undef> on failure.
=item offsetof
-offsetof() is C-specific.
+offsetof() is C-specific, you probably want to see L<perlfunc/pack> instead.
=item open
Returns C<undef> on failure.
+See also L<perlfunc/sysopen>.
+
=item opendir
Open a directory for reading.
=item pause
-This is similar to the C function C<pause()>.
+This is similar to the C function C<pause()>, which suspends
+the execution of the current process until a signal is received.
Returns C<undef> on failure.
=item perror
-This is identical to the C function C<perror()>.
+This is identical to the C function C<perror()>, which outputs to the
+standard error stream the specified message followed by ": " and the
+current error string. Use the C<warn()> function and the C<$!>
+variable instead, see L<perlfunc/warn> and L<perlvar>.
=item pipe
POSIX::write( $fd0, "hello", 5 );
POSIX::read( $fd1, $buf, 5 );
+See also L<perlfunc/pipe>.
+
=item pow
-Computes $x raised to the power $exponent.
+Computes C<$x> raised to the power C<$exponent>.
$ret = POSIX::pow( $x, $exponent );
+You can also use the C<**> operator, see L<perlop>.
+
=item printf
-Prints the specified arguments to STDOUT.
+Formats and prints the specified arguments to STDOUT.
+See also L<perlfunc/printf>.
=item putc
-putc() is C-specific--use print instead.
+putc() is C-specific, see L<perlfunc/print> instead.
=item putchar
-putchar() is C-specific--use print instead.
+putchar() is C-specific, see L<perlfunc/print> instead.
=item puts
-puts() is C-specific--use print instead.
+puts() is C-specific, see L<perlfunc/print> instead.
=item qsort
-qsort() is C-specific, use sort instead.
+qsort() is C-specific, see L<perlfunc/sort> instead.
=item raise
Sends the specified signal to the current process.
+See also L<perlfunc/kill> and the C<$$> in L<perlvar>.
=item rand
-rand() is non-portable, use Perl's rand instead.
+rand() is non-portable, see L<perlfunc/rand> instead.
=item read
Returns C<undef> on failure.
+See also L<perlfunc/sysread>.
+
=item readdir
-This is identical to Perl's builtin C<readdir()> function.
+This is identical to Perl's builtin C<readdir()> function
+for reading directory entries, see L<perlfunc/readdir>.
=item realloc
-realloc() is C-specific.
+realloc() is C-specific. Perl does memory management transparently.
=item remove
-This is identical to Perl's builtin C<unlink()> function.
+This is identical to Perl's builtin C<unlink()> function
+for removing files, see L<perlfunc/unlink>.
=item rename
-This is identical to Perl's builtin C<rename()> function.
+This is identical to Perl's builtin C<rename()> function
+for renaming files, see L<perlfunc/rename>.
=item rewind
=item rewinddir
-This is identical to Perl's builtin C<rewinddir()> function.
+This is identical to Perl's builtin C<rewinddir()> function for
+rewinding directory entry streams, see L<perlfunc/rewinddir>.
=item rmdir
-This is identical to Perl's builtin C<rmdir()> function.
+This is identical to Perl's builtin C<rmdir()> function
+for removing (empty) directories, see L<perlfunc/rmdir>.
=item scanf
-scanf() is C-specific--use <> and regular expressions instead.
+scanf() is C-specific--use <> and regular expressions instead,
+see L<perlre>.
=item setgid
=item setjmp
-setjmp() is C-specific: use eval {} instead.
+C<setjmp()> is C-specific: use C<eval {}> instead,
+see L<perlfunc/eval>.
=item setlocale
=item siglongjmp
-siglongjmp() is C-specific: use die instead.
+siglongjmp() is C-specific: use L<perlfunc/die> instead.
=item sigpending
=item sigsetjmp
-sigsetjmp() is C-specific: use eval {} instead.
+C<sigsetjmp()> is C-specific: use C<eval {}> instead,
+see L<perlfunc/eval>.
=item sigsuspend
=item sin
-This is identical to Perl's builtin C<sin()> function.
+This is identical to Perl's builtin C<sin()> function
+for returning the sine of the numerical argument,
+see L<perlfunc/sin>.
=item sinh
-This is identical to the C function C<sinh()>.
+This is identical to the C function C<sinh()>
+for returning the hyperbolic sine of the numerical argument.
=item sleep
-This is identical to Perl's builtin C<sleep()> function.
+This is identical to Perl's builtin C<sleep()> function
+for suspending the execution of the current for process
+for certain number of seconds, see L<perlfunc/sleep>.
=item sprintf
-This is identical to Perl's builtin C<sprintf()> function.
+This is similar to Perl's builtin C<sprintf()> function
+for returning a string that has the arguments formatted as requested,
+see L<perlfunc/sprintf>.
=item sqrt
This is identical to Perl's builtin C<sqrt()> function.
+for returning the square root of the numerical argument,
+see L<perlfunc/sqrt>.
=item srand
-srand().
+Give a seed the pseudorandom number generator, see L<perlfunc/srand>.
=item sscanf
-sscanf() is C-specific--use regular expressions instead.
+sscanf() is C-specific, use regular expressions instead,
+see L<perlre>.
=item stat
=item strcat
-strcat() is C-specific, use .= instead.
+strcat() is C-specific, use C<.=> instead, see L<perlop>.
=item strchr
-strchr() is C-specific, use index() instead.
+strchr() is C-specific, see L<perlfunc/index> instead.
=item strcmp
-strcmp() is C-specific, use eq instead.
+strcmp() is C-specific, use C<eq> instead, see L<perlop>.
=item strcoll
-This is identical to the C function C<strcoll()>.
+This is identical to the C function C<strcoll()>
+for collating (comparing) strings transformed using
+the C<strxfrm()> function. Not really needed since
+Perl can do this transparently, see L<perllocale>.
=item strcpy
-strcpy() is C-specific, use = instead.
+strcpy() is C-specific, use C<=> instead, see L<perlop>.
=item strcspn
=item strerror
Returns the error string for the specified errno.
+Identical to the string form of the C<$!>, see L<perlvar>.
=item strftime
=item strlen
-strlen() is C-specific, use length instead.
+strlen() is C-specific, use C<length()> instead, see L<perlfunc/length>.
=item strncat
-strncat() is C-specific, use .= instead.
+strncat() is C-specific, use C<.=> instead, see L<perlop>.
=item strncmp
-strncmp() is C-specific, use eq instead.
+strncmp() is C-specific, use C<eq> instead, see L<perlop>.
=item strncpy
-strncpy() is C-specific, use = instead.
-
-=item stroul
-
-stroul() is C-specific.
+strncpy() is C-specific, use C<=> instead, see L<perlop>.
=item strpbrk
-strpbrk() is C-specific.
+strpbrk() is C-specific, use regular expressions instead, see L<perlre>.
=item strrchr
-strrchr() is C-specific, use rindex() instead.
+strrchr() is C-specific, see L<perlfunc/rindex> instead.
=item strspn
-strspn() is C-specific.
+strspn() is C-specific, use regular expressions instead,
+see L<perlre>.
=item strstr
-This is identical to Perl's builtin C<index()> function.
+This is identical to Perl's builtin C<index()> function,
+see L<perlfunc/index>.
=item strtod
=item strtok
-strtok() is C-specific.
+strtok() is C-specific, use regular expressions instead, see
+L<perlre>, or L<perlfunc/split>.
=item strtol
=item strtoul
-String to unsigned (long) integer translation. strtoul is identical
-to strtol except that strtoul only parses unsigned integers. See
-I<strtol> for details.
+String to unsigned (long) integer translation. strtoul() is identical
+to strtol() except that strtoul() only parses unsigned integers. See
+L</strtol> for details.
-Note: Some vendors supply strtod and strtol but not strtoul.
-Other vendors that do suply strtoul parse "-1" as a valid value.
+Note: Some vendors supply strtod() and strtol() but not strtoul().
+Other vendors that do supply strtoul() parse "-1" as a valid value.
=item strxfrm
$dst = POSIX::strxfrm( $src );
+Used in conjunction with the C<strcoll()> function, see L</strcoll>.
+
+Not really needed since Perl can do this transparently, see
+L<perllocale>.
+
=item sysconf
Retrieves values of system configurable variables.
=item system
-This is identical to Perl's builtin C<system()> function.
+This is identical to Perl's builtin C<system()> function, see
+L<perlfunc/system>.
=item tan
-This is identical to the C function C<tan()>.
+This is identical to the C function C<tan()>, returning the
+tangent of the numerical argument.
=item tanh
-This is identical to the C function C<tanh()>.
+This is identical to the C function C<tanh()>, returning the
+hyperbolic tangent of the numerical argument.
=item tcdrain
-This is similar to the C function C<tcdrain()>.
+This is similar to the C function C<tcdrain()> for draining
+the output queue of its argument stream.
Returns C<undef> on failure.
=item tcflow
-This is similar to the C function C<tcflow()>.
+This is similar to the C function C<tcflow()> for controlling
+the flow of its argument stream.
Returns C<undef> on failure.
=item tcflush
-This is similar to the C function C<tcflush()>.
+This is similar to the C function C<tcflush()> for flushing
+the I/O buffers of its argumeny stream.
Returns C<undef> on failure.
=item tcgetpgrp
-This is identical to the C function C<tcgetpgrp()>.
+This is identical to the C function C<tcgetpgrp()> for returning the
+process group id of the foreground process group of the controlling
+terminal.
=item tcsendbreak
-This is similar to the C function C<tcsendbreak()>.
+This is similar to the C function C<tcsendbreak()> for sending
+a break on its argument stream.
Returns C<undef> on failure.
=item tcsetpgrp
-This is similar to the C function C<tcsetpgrp()>.
+This is similar to the C function C<tcsetpgrp()> for setting the
+process group id of the foreground process group of the controlling
+terminal.
Returns C<undef> on failure.
=item time
-This is identical to Perl's builtin C<time()> function.
+This is identical to Perl's builtin C<time()> function
+for returning the number of seconds since the epoch
+(whatever it is for the system), see L<perlfunc/time>.
=item times
$tmpfile = POSIX::tmpnam();
+See also the L<File::Temp> module.
+
=item tolower
-This is identical to Perl's builtin C<lc()> function.
+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<lc()> function,
+see L<perlfunc/lc>, or the equivalent C<\L> operator inside doublequotish
+strings.
=item toupper
-This is identical to Perl's builtin C<uc()> function.
+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<uc()> function,
+see L<perlfunc/uc>, or the equivalent C<\U> operator inside doublequotish
+strings.
=item ttyname
-This is identical to the C function C<ttyname()>.
+This is identical to the C function C<ttyname()> for returning the
+name of the current terminal.
=item tzname
=item tzset
-This is identical to the C function C<tzset()>.
+This is identical to the C function C<tzset()> for setting
+the current timezone based on the environment variable C<TZ>,
+to be used by C<ctime()>, C<localtime()>, C<mktime()>, and C<strftime()>
+functions.
=item umask
-This is identical to Perl's builtin C<umask()> function.
+This is identical to Perl's builtin C<umask()> function
+for setting (and querying) the file creation permission mask,
+see L<perlfunc/umask>.
=item uname
=item unlink
-This is identical to Perl's builtin C<unlink()> function.
+This is identical to Perl's builtin C<unlink()> function
+for removing files, see L<perlfunc/unlink>.
=item utime
-This is identical to Perl's builtin C<utime()> function.
+This is identical to Perl's builtin C<utime()> function
+for changing the time stamps of files and directories,
+see L<perlfunc/utime>.
=item vfprintf
-vfprintf() is C-specific.
+vfprintf() is C-specific, see L<perlfunc/printf> instead.
=item vprintf
-vprintf() is C-specific.
+vprintf() is C-specific, see L<perlfunc/printf> instead.
=item vsprintf
-vsprintf() is C-specific.
+vsprintf() is C-specific, see L<perlfunc/sprintf> instead.
=item wait
-This is identical to Perl's builtin C<wait()> function.
+This is identical to Perl's builtin C<wait()> function,
+see L<perlfunc/wait>.
=item waitpid
Wait for a child process to change state. This is identical to Perl's
-builtin C<waitpid()> function.
+builtin C<waitpid()> function, see L<perlfunc/waitpid>.
$pid = POSIX::waitpid( -1, &POSIX::WNOHANG );
print "status = ", ($? / 256), "\n";
Returns C<undef> on failure.
+See also L<perlfunc/syswrite>.
+
=back
=head1 CLASSES
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