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PERLFUNC(1)							   PERLFUNC(1)

NAME
       perlfunc - Perl builtin functions

DESCRIPTION
       The functions in this section can serve as terms in an expression.
       They fall into two major categories: list operators and named unary
       operators.  These differ in their precedence relationship with a
       following comma.	 (See the precedence table in the perlop manpage.)
       List operators take more than one argument, while unary operators can
       never take more than one argument.  Thus, a comma terminates the
       argument of a unary operator, but merely separates the arguments of a
       list operator.  A unary operator generally provides a scalar context to
       its argument, while a list operator may provide either scalar and list
       contexts for its arguments.  If it does both, the scalar arguments will
       be first, and the list argument will follow.  (Note that there can only
       ever be one list argument.)  For instance, splice() has three scalar
       arguments followed by a list.

       In the syntax descriptions that follow, list operators that expect a
       list (and provide list context for the elements of the list) are shown
       with LIST as an argument.  Such a list may consist of any combination
       of scalar arguments or list values; the list values will be included in
       the list as if each individual element were interpolated at that point
       in the list, forming a longer single-dimensional list value.  Elements
       of the LIST should be separated by commas.

       Any function in the list below may be used either with or without
       parentheses around its arguments.  (The syntax descriptions omit the
       parens.)	 If you use the parens, the simple (but occasionally
       surprising) rule is this: It LOOKS like a function, therefore it IS a
       function, and precedence doesn't matter.	 Otherwise it's a list
       operator or unary operator, and precedence does matter.	And whitespace
       between the function and left parenthesis doesn't count--so you need to
       be careful sometimes:

	   print 1+2+3;	       # Prints 6.
	   print(1+2) + 3;     # Prints 3.
	   print (1+2)+3;      # Also prints 3!
	   print +(1+2)+3;     # Prints 6.
	   print ((1+2)+3);    # Prints 6.

       If you run Perl with the -w switch it can warn you about this.  For
       example, the third line above produces:

	   print (...) interpreted as function at - line 1.
	   Useless use of integer addition in void context at - line 1.

       For functions that can be used in either a scalar or list context, non-
       abortive failure is generally indicated in a scalar context by
       returning the undefined value, and in a list context by returning the
       null list.

       Remember the following rule:

       ·    THERE IS NO GENERAL RULE FOR CONVERTING A LIST INTO A SCALAR!

       Each operator and function decides which sort of value it would be most
       appropriate to return in a scalar context.  Some operators return the
       length of the list that would have been returned in a list context.
       Some operators return the first value in the list.  Some operators
       return the last value in the list.  Some operators return a count of
       successful operations.  In general, they do what you want, unless you
       want consistency.

       -X FILEHANDLE

       -X EXPR

       -X      A file test, where X is one of the letters listed below.	 This
	       unary operator takes one argument, either a filename or a
	       filehandle, and tests the associated file to see if something
	       is true about it.  If the argument is omitted, tests $_, except
	       for -t, which tests STDIN.  Unless otherwise documented, it
	       returns 1 for TRUE and '' for FALSE, or the undefined value if
	       the file doesn't exist.	Despite the funny names, precedence is
	       the same as any other named unary operator, and the argument
	       may be parenthesized like any other unary operator.  The
	       operator may be any of:

		   -r  File is readable by effective uid/gid.
		   -w  File is writable by effective uid/gid.
		   -x  File is executable by effective uid/gid.
		   -o  File is owned by effective uid.

		   -R  File is readable by real uid/gid.
		   -W  File is writable by real uid/gid.
		   -X  File is executable by real uid/gid.
		   -O  File is owned by real uid.

		   -e  File exists.
		   -z  File has zero size.
		   -s  File has non-zero size (returns size).

		   -f  File is a plain file.
		   -d  File is a directory.
		   -l  File is a symbolic link.
		   -p  File is a named pipe (FIFO).
		   -S  File is a socket.
		   -b  File is a block special file.
		   -c  File is a character special file.
		   -t  Filehandle is opened to a tty.

		   -u  File has setuid bit set.
		   -g  File has setgid bit set.
		   -k  File has sticky bit set.

		   -T  File is a text file.
		   -B  File is a binary file (opposite of -T).

		   -M  Age of file in days when script started.
		   -A  Same for access time.
		   -C  Same for inode change time.

	       The interpretation of the file permission operators -r, -R, -w,
	       -W, -x and -X is based solely on the mode of the file and the
	       uids and gids of the user.  There may be other reasons you
	       can't actually read, write or execute the file.	Also note
	       that, for the superuser, -r, -R, -w and -W always return 1, and
	       -x and -X return 1 if any execute bit is set in the mode.
	       Scripts run by the superuser may thus need to do a stat() in
	       order to determine the actual mode of the file, or temporarily
	       set the uid to something else.

	       Example:

		   while (<>) {
		       chop;
		       next unless -f $_;      # ignore specials
		       ...
		   }

	       Note that -s/a/b/ does not do a negated substitution.  Saying
	       -exp($foo) still works as expected, however--only single
	       letters following a minus are interpreted as file tests.

	       The -T and -B switches work as follows.	The first block or so
	       of the file is examined for odd characters such as strange
	       control codes or characters with the high bit set.  If too many
	       odd characters (>30%) are found, it's a -B file, otherwise it's
	       a -T file.  Also, any file containing null in the first block
	       is considered a binary file.  If -T or -B is used on a
	       filehandle, the current stdio buffer is examined rather than
	       the first block.	 Both -T and -B return TRUE on a null file, or
	       a file at EOF when testing a filehandle.

	       If any of the file tests (or either the stat() or lstat()
	       operators) are given the special filehandle consisting of a
	       solitary underline, then the stat structure of the previous
	       file test (or stat operator) is used, saving a system call.
	       (This doesn't work with -t, and you need to remember that
	       lstat() and -l will leave values in the stat structure for the
	       symbolic link, not the real file.)  Example:

		   print "Can do.\n" if -r $a ⎪⎪ -w _ ⎪⎪ -x _;

		   stat($filename);
		   print "Readable\n" if -r _;
		   print "Writable\n" if -w _;
		   print "Executable\n" if -x _;
		   print "Setuid\n" if -u _;
		   print "Setgid\n" if -g _;
		   print "Sticky\n" if -k _;
		   print "Text\n" if -T _;
		   print "Binary\n" if -B _;

       abs VALUE
	       Returns the absolute value of its argument.

       accept NEWSOCKET,GENERICSOCKET
	       Accepts an incoming socket connect, just as the accept(2)
	       system call does.  Returns the packed address if it succeeded,
	       FALSE otherwise.	 See example in the perlipc manpage.

       alarm SECONDS
	       Arranges to have a SIGALRM delivered to this process after the
	       specified number of seconds have elapsed.  (On some machines,
	       unfortunately, the elapsed time may be up to one second less
	       than you specified because of how seconds are counted.)	Only
	       one timer may be counting at once.  Each call disables the
	       previous timer, and an argument of 0 may be supplied to cancel
	       the previous timer without starting a new one.  The returned
	       value is the amount of time remaining on the previous timer.

	       For sleeps of finer granularity than one second, you may use
	       Perl's syscall() interface to access setitimer(2) if your
	       system supports it, or else see the select() entry elsewhere in
	       this documentbelow.

       atan2 Y,X
	       Returns the arctangent of Y/X in the range - to .

       bind SOCKET,NAME
	       Binds a network address to a socket, just as the bind system
	       call does.  Returns TRUE if it succeeded, FALSE otherwise.
	       NAME should be a packed address of the appropriate type for the
	       socket.	See example in the perlipc manpage.

       binmode FILEHANDLE
	       Arranges for the file to be read or written in "binary" mode in
	       operating systems that distinguish between binary and text
	       files.  Files that are not in binary mode have CR LF sequences
	       translated to LF on input and LF translated to CR LF on output.
	       Binmode has no effect under Unix; in DOS, it may be imperative.
	       If FILEHANDLE is an expression, the value is taken as the name
	       of the filehandle.

       bless REF,PACKAGE

       bless REF
	       This function tells the referenced object (passed as REF) that
	       it is now an object in PACKAGE--or the current package if no
	       PACKAGE is specified, which is the usual case.  It returns the
	       reference for convenience, since a bless() is often the last
	       thing in a constructor.	See the perlobj manpage for more about
	       the blessing (and blessings) of objects.

       caller EXPR

       caller  Returns the context of the current subroutine call.  In a
	       scalar context, returns TRUE if there is a caller, that is, if
	       we're in a subroutine or eval() or require(), and FALSE
	       otherwise.  In a list context, returns

		   ($package, $filename, $line) = caller;

	       With EXPR, it returns some extra information that the debugger
	       uses to print a stack trace.  The value of EXPR indicates how
	       many call frames to go back before the current one.

		   ($package, $filename, $line,
		    $subroutine, $hasargs, $wantargs) = caller($i);

	       Furthermore, when called from within the DB package, caller
	       returns more detailed information: it sets sets the list
	       variable @DB:args to be the arguments with which that
	       subroutine was invoked.

       chdir EXPR
	       Changes the working directory to EXPR, if possible.  If EXPR is
	       omitted, changes to home directory.  Returns TRUE upon success,
	       FALSE otherwise.	 See example under die().

       chmod LIST
	       Changes the permissions of a list of files.  The first element
	       of the list must be the numerical mode.	Returns the number of
	       files successfully changed.

		   $cnt = chmod 0755, 'foo', 'bar';
		   chmod 0755, @executables;

       chomp VARIABLE

       chomp LIST

       chomp   This is a slightly safer version of chop (see below).  It
	       removes any line ending that corresponds to the current value
	       of $/ (also known as $INPUT_RECORD_SEPARATOR in the English
	       module).	 It returns the number of characters removed.  It's
	       often used to remove the newline from the end of an input
	       record when you're worried that the final record may be missing
	       its newline.  When in paragraph mode ($/ = ""), it removes all
	       trailing newlines from the string.  If VARIABLE is omitted, it
	       chomps $_.  Example:

		   while (<>) {
		       chomp;  # avoid \n on last field
		       @array = split(/:/);
		       ...
		   }

	       You can actually chomp anything that's an lvalue, including an
	       assignment:

		   chomp($cwd = `pwd`);
		   chomp($answer = <STDIN>);

	       If you chomp a list, each element is chomped, and the total
	       number of characters removed is returned.

       chop VARIABLE

       chop LIST

       chop    Chops off the last character of a string and returns the
	       character chopped.  It's used primarily to remove the newline
	       from the end of an input record, but is much more efficient
	       than s/\n// because it neither scans nor copies the string.  If
	       VARIABLE is omitted, chops $_.  Example:

		   while (<>) {
		       chop;   # avoid \n on last field
		       @array = split(/:/);
		       ...
		   }

	       You can actually chop anything that's an lvalue, including an
	       assignment:

		   chop($cwd = `pwd`);
		   chop($answer = <STDIN>);

	       If you chop a list, each element is chopped.  Only the value of
	       the last chop is returned.

	       Note that chop returns the last character.  To return all but
	       the last character, use substr($string, 0, -1).

       chown LIST
	       Changes the owner (and group) of a list of files.  The first
	       two elements of the list must be the NUMERICAL uid and gid, in
	       that order.  Returns the number of files successfully changed.

		   $cnt = chown $uid, $gid, 'foo', 'bar';
		   chown $uid, $gid, @filenames;

	       Here's an example that looks up non-numeric uids in the passwd
	       file:

		   print "User: ";
		   chop($user = <STDIN>);
		   print "Files: "
		   chop($pattern = <STDIN>);

		   ($login,$pass,$uid,$gid) = getpwnam($user)
		       or die "$user not in passwd file";

		   @ary = <${pattern}>;	       # expand filenames
		   chown $uid, $gid, @ary;

       chr NUMBER
	       Returns the character represented by that NUMBER in the
	       character set.  For example, chr(65) is "A" in ASCII.

       chroot FILENAME
	       Does the same as the system call of that name.  If you don't
	       know what it does, don't worry about it.	 If FILENAME is
	       omitted, does chroot to $_.

       close FILEHANDLE
	       Closes the file or pipe associated with the file handle,
	       returning TRUE only if stdio successfully flushes buffers and
	       closes the system file descriptor.  You don't have to close
	       FILEHANDLE if you are immediately going to do another open on
	       it, since open will close it for you.  (See open().)  However,
	       an explicit close on an input file resets the line counter
	       ($.), while the implicit close done by open() does not.	Also,
	       closing a pipe will wait for the process executing on the pipe
	       to complete, in case you want to look at the output of the pipe
	       afterwards.  Closing a pipe explicitly also puts the status
	       value of the command into $?.  Example:

		   open(OUTPUT, '⎪sort >foo'); # pipe to sort
		   ...			       # print stuff to output
		   close OUTPUT;	       # wait for sort to finish
		   open(INPUT, 'foo');	       # get sort's results

	       FILEHANDLE may be an expression whose value gives the real
	       filehandle name.

       closedir DIRHANDLE
	       Closes a directory opened by opendir().

       connect SOCKET,NAME
	       Attempts to connect to a remote socket, just as the connect
	       system call does.  Returns TRUE if it succeeded, FALSE
	       otherwise.  NAME should be a packed address of the appropriate
	       type for the socket.  See example in the perlipc manpage.

       cos EXPR
	       Returns the cosine of EXPR (expressed in radians).  If EXPR is
	       omitted takes cosine of $_.

       crypt PLAINTEXT,SALT
	       Encrypts a string exactly like the crypt(3) function in the C
	       library.	 Useful for checking the password file for lousy
	       passwords, amongst other things.	 Only the guys wearing white
	       hats should do this.

	       Here's an example that makes sure that whoever runs this
	       program knows their own password:

		   $pwd = (getpwuid($<))[1];
		   $salt = substr($pwd, 0, 2);

		   system "stty -echo";
		   print "Password: ";
		   chop($word = <STDIN>);
		   print "\n";
		   system "stty echo";

		   if (crypt($word, $salt) ne $pwd) {
		       die "Sorry...\n";
		   } else {
		       print "ok\n";
		   }

	       Of course, typing in your own password to whoever asks you for
	       it is unwise.

       dbmclose ASSOC_ARRAY
	       [This function has been superseded by the untie() function.]

	       Breaks the binding between a DBM file and an associative array.

       dbmopen ASSOC,DBNAME,MODE
	       [This function has been superseded by the tie() function.]

	       This binds a dbm(3) or ndbm(3) file to an associative array.
	       ASSOC is the name of the associative array.  (Unlike normal
	       open, the first argument is NOT a filehandle, even though it
	       looks like one).	 DBNAME is the name of the database (without
	       the .dir or .pag extension).  If the database does not exist,
	       it is created with protection specified by MODE (as modified by
	       the umask()).  If your system only supports the older DBM
	       functions, you may perform only one dbmopen() in your program.
	       If your system has neither DBM nor ndbm, calling dbmopen()
	       produces a fatal error.

	       If you don't have write access to the DBM file, you can only
	       read associative array variables, not set them.	If you want to
	       test whether you can write, either use file tests or try
	       setting a dummy array entry inside an eval(), which will trap
	       the error.

	       Note that functions such as keys() and values() may return huge
	       array values when used on large DBM files.  You may prefer to
	       use the each() function to iterate over large DBM files.
	       Example:

		   # print out history file offsets
		   dbmopen(%HIST,'/usr/lib/news/history',0666);
		   while (($key,$val) = each %HIST) {
		       print $key, ' = ', unpack('L',$val), "\n";
		   }
		   dbmclose(%HIST);

       defined EXPR
	       Returns a boolean value saying whether the lvalue EXPR has a
	       real value or not.  Many operations return the undefined value
	       under exceptional conditions, such as end of file,
	       uninitialized variable, system error and such.  This function
	       allows you to distinguish between an undefined null scalar and
	       a defined null scalar with operations that might return a real
	       null string, such as referencing elements of an array.  You may
	       also check to see if arrays or subroutines exist.  Use of
	       defined on predefined variables is not guaranteed to produce
	       intuitive results.

	       When used on a hash array element, it tells you whether the
	       value is defined, not whether the key exists in the hash.  Use
	       exists() for that.

	       Examples:

		   print if defined $switch{'D'};
		   print "$val\n" while defined($val = pop(@ary));
		   die "Can't readlink $sym: $!"
		       unless defined($value = readlink $sym);
		   eval '@foo = ()' if defined(@foo);
		   die "No XYZ package defined" unless defined %_XYZ;
		   sub foo { defined &$bar ? &$bar(@_) : die "No bar"; }

	       See also undef().

       delete EXPR
	       Deletes the specified value from its hash array.	 Returns the
	       deleted value, or the undefined value if nothing was deleted.
	       Deleting from $ENV{} modifies the environment.  Deleting from
	       an array tied to a DBM file deletes the entry from the DBM
	       file.  (But deleting from a tie()d hash doesn't necessarily
	       return anything.)

	       The following deletes all the values of an associative array:

		   foreach $key (keys %ARRAY) {
		       delete $ARRAY{$key};
		   }

	       (But it would be faster to use the undef() command.)  Note that
	       the EXPR can be arbitrarily complicated as long as the final
	       operation is a hash key lookup:

		   delete $ref->[$x][$y]{$key};

       die LIST
	       Outside of an eval(), prints the value of LIST to STDERR and
	       exits with the current value of $!  (errno).  If $! is 0, exits
	       with the value of ($? >> 8) (backtick `command` status).	 If
	       ($? >> 8) is 0, exits with 255.	Inside an eval(), the error
	       message is stuffed into $@, and the eval() is terminated with
	       the undefined value.

	       Equivalent examples:

		   die "Can't cd to spool: $!\n" unless chdir '/usr/spool/news';
		   chdir '/usr/spool/news' or die "Can't cd to spool: $!\n"

	       If the value of EXPR does not end in a newline, the current
	       script line number and input line number (if any) are also
	       printed, and a newline is supplied.  Hint: sometimes appending
	       ", stopped" to your message will cause it to make better sense
	       when the string "at foo line 123" is appended.  Suppose you are
	       running script "canasta".

		   die "/etc/games is no good";
		   die "/etc/games is no good, stopped";

	       produce, respectively

		   /etc/games is no good at canasta line 123.
		   /etc/games is no good, stopped at canasta line 123.

	       See also exit() and warn().

       do BLOCK
	       Not really a function.  Returns the value of the last command
	       in the sequence of commands indicated by BLOCK.	When modified
	       by a loop modifier, executes the BLOCK once before testing the
	       loop condition.	(On other statements the loop modifiers test
	       the conditional first.)

       do SUBROUTINE(LIST)
	       A deprecated form of subroutine call.  See the perlsub manpage.

       do EXPR Uses the value of EXPR as a filename and executes the contents
	       of the file as a Perl script.  Its primary use is to include
	       subroutines from a Perl subroutine library.

		   do 'stat.pl';

	       is just like

		   eval `cat stat.pl`;

	       except that it's more efficient, more concise, keeps track of
	       the current filename for error messages, and searches all the
	       -I libraries if the file isn't in the current directory (see
	       also the @INC array in the section on Predefined Names in the
	       perlvar manpage).  It's the same, however, in that it does
	       reparse the file every time you call it, so you probably don't
	       want to do this inside a loop.

	       Note that inclusion of library modules is better done with the
	       use() and require() operators.

       dump LABEL
	       This causes an immediate core dump.  Primarily this is so that
	       you can use the undump program to turn your core dump into an
	       executable binary after having initialized all your variables
	       at the beginning of the program.	 When the new binary is
	       executed it will begin by executing a goto LABEL (with all the
	       restrictions that goto suffers).	 Think of it as a goto with an
	       intervening core dump and reincarnation.	 If LABEL is omitted,
	       restarts the program from the top.  WARNING: any files opened
	       at the time of the dump will NOT be open any more when the
	       program is reincarnated, with possible resulting confusion on
	       the part of Perl.  See also -u option in the perlrun manpage.

	       Example:

		   #!/usr/bin/perl
		   require 'getopt.pl';
		   require 'stat.pl';
		   %days = (
		       'Sun' => 1,
		       'Mon' => 2,
		       'Tue' => 3,
		       'Wed' => 4,
		       'Thu' => 5,
		       'Fri' => 6,
		       'Sat' => 7,
		   );

		   dump QUICKSTART if $ARGV[0] eq '-d';

		   QUICKSTART:
		   Getopt('f');

       each ASSOC_ARRAY
	       Returns a 2 element array consisting of the key and value for
	       the next value of an associative array, so that you can iterate
	       over it.	 Entries are returned in an apparently random order.
	       When the array is entirely read, a null array is returned
	       (which when assigned produces a FALSE (0) value).  The next
	       call to each() after that will start iterating again.  The
	       iterator can be reset only by reading all the elements from the
	       array.  You should not add elements to an array while you're
	       iterating over it.  There is a single iterator for each
	       associative array, shared by all each(), keys() and values()
	       function calls in the program.  The following prints out your
	       environment like the printenv(1) program, only in a different
	       order:

		   while (($key,$value) = each %ENV) {
		       print "$key=$value\n";
		   }

	       See also keys() and values().

       eof FILEHANDLE

       eof     Returns 1 if the next read on FILEHANDLE will return end of
	       file, or if FILEHANDLE is not open.  FILEHANDLE may be an
	       expression whose value gives the real filehandle name.  (Note
	       that this function actually reads a character and then
	       ungetc()s it, so it is not very useful in an interactive
	       context.)  Do not read from a terminal file (or call
	       eof(FILEHANDLE) on it) after end-of-file is reached.  Filetypes
	       such as terminals may lose the end-of-file condition if you do.

	       An eof without an argument uses the last file read as argument.
	       Empty parentheses () may be used to indicate the pseudo file
	       formed of the files listed on the command line, i.e.  eof() is
	       reasonable to use inside a while (<>) loop to detect the end of
	       only the last file.  Use eof(ARGV) or eof without the
	       parentheses to test EACH file in a while (<>) loop.  Examples:

		   # reset line numbering on each input file
		   while (<>) {
		       print "$.\t$_";
		       close(ARGV) if (eof);   # Not eof().
		   }

		   # insert dashes just before last line of last file
		   while (<>) {
		       if (eof()) {
			   print "--------------\n";
			   close(ARGV);	       # close or break; is needed if we
					       # are reading from the terminal
		       }
		       print;
		   }

	       Practical hint: you almost never need to use eof in Perl,
	       because the input operators return undef when they run out of
	       data.

       eval EXPR

       eval BLOCK
	       EXPR is parsed and executed as if it were a little Perl
	       program.	 It is executed in the context of the current Perl
	       program, so that any variable settings, subroutine or format
	       definitions remain afterwards.  The value returned is the value
	       of the last expression evaluated, or a return statement may be
	       used, just as with subroutines.

	       If there is a syntax error or runtime error, or a die()
	       statement is executed, an undefined value is returned by
	       eval(), and $@ is set to the error message.  If there was no
	       error, $@ is guaranteed to be a null string.  If EXPR is
	       omitted, evaluates $_.  The final semicolon, if any, may be
	       omitted from the expression.

	       Note that, since eval() traps otherwise-fatal errors, it is
	       useful for determining whether a particular feature (such as
	       dbmopen() or symlink()) is implemented.	It is also Perl's
	       exception trapping mechanism, where the die operator is used to
	       raise exceptions.

	       If the code to be executed doesn't vary, you may use the eval-
	       BLOCK form to trap run-time errors without incurring the
	       penalty of recompiling each time.  The error, if any, is still
	       returned in $@.	Examples:

		   # make divide-by-zero non-fatal
		   eval { $answer = $a / $b; }; warn $@ if $@;

		   # same thing, but less efficient
		   eval '$answer = $a / $b'; warn $@ if $@;

		   # a compile-time error
		   eval { $answer = };

		   # a run-time error
		   eval '$answer =';   # sets $@

	       With an eval(), you should be especially careful to remember
	       what's being looked at when:

		   eval $x;	       # CASE 1
		   eval "$x";	       # CASE 2

		   eval '$x';	       # CASE 3
		   eval { $x };	       # CASE 4

		   eval "\$$x++"       # CASE 5
		   $$x++;	       # CASE 6

	       Cases 1 and 2 above behave identically: they run the code
	       contained in the variable $x.  (Although case 2 has misleading
	       double quotes making the reader wonder what else might be
	       happening (nothing is).) Cases 3 and 4 likewise behave in the
	       same way: they run the code <$x>, which does nothing at all.
	       (Case 4 is preferred for purely visual reasons.) Case 5 is a
	       place where normally you WOULD like to use double quotes,
	       except in that particular situation, you can just use symbolic
	       references instead, as in case 6.

       exec LIST
	       The exec() function executes a system command AND NEVER
	       RETURNS.	 Use the system() function if you want it to return.

	       If there is more than one argument in LIST, or if LIST is an
	       array with more than one value, calls execvp(3) with the
	       arguments in LIST.  If there is only one scalar argument, the
	       argument is checked for shell metacharacters.  If there are
	       any, the entire argument is passed to /bin/sh -c for parsing.
	       If there are none, the argument is split into words and passed
	       directly to execvp(), which is more efficient.  Note: exec()
	       (and system(0) do not flush your output buffer, so you may need
	       to set $⎪ to avoid lost output.	Examples:

		   exec '/bin/echo', 'Your arguments are: ', @ARGV;
		   exec "sort $outfile ⎪ uniq";

	       If you don't really want to execute the first argument, but
	       want to lie to the program you are executing about its own
	       name, you can specify the program you actually want to run as
	       an "indirect object" (without a comma) in front of the LIST.
	       (This always forces interpretation of the LIST as a multi-
	       valued list, even if there is only a single scalar in the
	       list.)  Example:

		   $shell = '/bin/csh';
		   exec $shell '-sh';	       # pretend it's a login shell

	       or, more directly,

		   exec {'/bin/csh'} '-sh';    # pretend it's a login shell

       exists EXPR
	       Returns TRUE if the specified hash key exists in its hash
	       array, even if the corresponding value is undefined.

		   print "Exists\n" if exists $array{$key};
		   print "Defined\n" if defined $array{$key};
		   print "True\n" if $array{$key};

	       A hash element can only be TRUE if it's defined, and defined if
	       it exists, but the reverse doesn't necessarily hold true.

	       Note that the EXPR can be arbitrarily complicated as long as
	       the final operation is a hash key lookup:

		   if (exists $ref->[$x][$y]{$key}) { ... }

       exit EXPR
	       Evaluates EXPR and exits immediately with that value.
	       (Actually, it calls any defined END routines first, but the END
	       routines may not abort the exit.	 Likewise any object
	       destructors that need to be called are called before exit.)
	       Example:

		   $ans = <STDIN>;
		   exit 0 if $ans =~ /^[Xx]/;

	       See also die().	If EXPR is omitted, exits with 0 status.

       exp EXPR
	       Returns e (the natural logarithm base) to the power of EXPR.
	       If EXPR is omitted, gives exp($_).

       fcntl FILEHANDLE,FUNCTION,SCALAR
	       Implements the fcntl(2) function.  You'll probably have to say

		   use Fcntl;

	       first to get the correct function definitions.  Argument
	       processing and value return works just like ioctl() below.
	       Note that fcntl() will produce a fatal error if used on a
	       machine that doesn't implement fcntl(2).	 For example:

		   use Fcntl;
		   fcntl($filehandle, F_GETLK, $packed_return_buffer);

       fileno FILEHANDLE
	       Returns the file descriptor for a filehandle.  This is useful
	       for constructing bitmaps for select().  If FILEHANDLE is an
	       expression, the value is taken as the name of the filehandle.

       flock FILEHANDLE,OPERATION
	       Calls flock(2) on FILEHANDLE.  See the flock(2) manpage for
	       definition of OPERATION.	 Returns TRUE for success, FALSE on
	       failure.	 Will produce a fatal error if used on a machine that
	       doesn't implement flock(2).  Here's a mailbox appender for BSD
	       systems.

		   $LOCK_SH = 1;
		   $LOCK_EX = 2;
		   $LOCK_NB = 4;
		   $LOCK_UN = 8;

		   sub lock {
		       flock(MBOX,$LOCK_EX);
		       # and, in case someone appended
		       # while we were waiting...
		       seek(MBOX, 0, 2);
		   }

		   sub unlock {
		       flock(MBOX,$LOCK_UN);
		   }

		   open(MBOX, ">>/usr/spool/mail/$ENV{'USER'}")
			   or die "Can't open mailbox: $!";

		   lock();
		   print MBOX $msg,"\n\n";
		   unlock();

	       Note that flock() can't lock things over the network.  You need
	       to do locking with fcntl() for that.

       fork    Does a fork(2) system call.  Returns the child pid to the
	       parent process and 0 to the child process, or undef if the fork
	       is unsuccessful.	 Note: unflushed buffers remain unflushed in
	       both processes, which means you may need to set $⎪ ($AUTOFLUSH
	       in English) or call the autoflush() FileHandle method to avoid
	       duplicate output.

	       If you fork() without ever waiting on your children, you will
	       accumulate zombies:

		   $SIG{'CHLD'} = sub { wait };

	       There's also the double-fork trick (error checking on fork()
	       returns omitted);

		   unless ($pid = fork) {
		       unless (fork) {
			   exec "what you really wanna do";
			   die "no exec";
			   # ... or ...
			   some_perl_code_here;
			   exit 0;
		       }
		       exit 0;
		   }
		   waitpid($pid,0);

       formline PICTURE, LIST
	       This is an internal function used by formats, though you may
	       call it too.  It formats (see the perlform manpage) a list of
	       values according to the contents of PICTURE, placing the output
	       into the format output accumulator, $^A.	 Eventually, when a
	       write() is done, the contents of $^A are written to some
	       filehandle, but you could also read $^A yourself and then set
	       $^A back to "".	Note that a format typically does one
	       formline() per line of form, but the formline() function itself
	       doesn't care how many newlines are embedded in the PICTURE.
	       This means that the ~ and ~~ tokens will treat the entire
	       PICTURE as a single line.  You may therefore need to use
	       multiple formlines to implement a single record format, just
	       like the format compiler.

	       Be careful if you put double quotes around the picture, since
	       an "@" character may be taken to mean the beginning of an array
	       name.  formline() always returns TRUE.

       getc FILEHANDLE

       getc    Returns the next character from the input file attached to
	       FILEHANDLE, or a null string at end of file.  If FILEHANDLE is
	       omitted, reads from STDIN.

       getlogin
	       Returns the current login from /etc/utmp, if any.  If null, use
	       getpwuid().

		   $login = getlogin ⎪⎪ (getpwuid($<))[0] ⎪⎪ "Kilroy";

       getpeername SOCKET
	       Returns the packed sockaddr address of other end of the SOCKET
	       connection.

		   # An internet sockaddr
		   $sockaddr = 'S n a4 x8';
		   $hersockaddr = getpeername(S);
		   ($family, $port, $heraddr) = unpack($sockaddr,$hersockaddr);

       getpgrp PID
	       Returns the current process group for the specified PID, 0 for
	       the current process.  Will produce a fatal error if used on a
	       machine that doesn't implement getpgrp(2).  If PID is omitted,
	       returns process group of current process.

       getppid Returns the process id of the parent process.

       getpriority WHICH,WHO
	       Returns the current priority for a process, a process group, or
	       a user.	(See the getpriority(2) manpage.)  Will produce a
	       fatal error if used on a machine that doesn't implement
	       getpriority(2).

       getpwnam NAME

       getgrnam NAME

       gethostbyname NAME

       getnetbyname NAME

       getprotobyname NAME

       getpwuid UID

       getgrgid GID

       getservbyname NAME,PROTO

       gethostbyaddr ADDR,ADDRTYPE

       getnetbyaddr ADDR,ADDRTYPE

       getprotobynumber NUMBER

       getservbyport PORT,PROTO

       getpwent

       getgrent

       gethostent

       getnetent

       getprotoent

       getservent

       setpwent

       setgrent

       sethostent STAYOPEN

       setnetent STAYOPEN

       setprotoent STAYOPEN

       setservent STAYOPEN

       endpwent

       endgrent

       endhostent

       endnetent

       endprotoent

       endservent
	       These routines perform the same functions as their counterparts
	       in the system library.  Within a list context, the return
	       values from the various get routines are as follows:

		   ($name,$passwd,$uid,$gid,
		      $quota,$comment,$gcos,$dir,$shell) = getpw*
		   ($name,$passwd,$gid,$members) = getgr*
		   ($name,$aliases,$addrtype,$length,@addrs) = gethost*
		   ($name,$aliases,$addrtype,$net) = getnet*
		   ($name,$aliases,$proto) = getproto*
		   ($name,$aliases,$port,$proto) = getserv*

	       (If the entry doesn't exist you get a null list.)

	       Within a scalar context, you get the name, unless the function
	       was a lookup by name, in which case you get the other thing,
	       whatever it is.	(If the entry doesn't exist you get the
	       undefined value.)  For example:

		   $uid = getpwnam
		   $name = getpwuid
		   $name = getpwent
		   $gid = getgrnam
		   $name = getgrgid
		   $name = getgrent
		   etc.

	       The $members value returned by getgr*() is a space separated
	       list of the login names of the members of the group.

	       For the gethost*() functions, if the h_errno variable is
	       supported in C, it will be returned to you via $? if the
	       function call fails.  The @addrs value returned by a successful
	       call is a list of the raw addresses returned by the
	       corresponding system library call.  In the Internet domain,
	       each address is four bytes long and you can unpack it by saying
	       something like:

		   ($a,$b,$c,$d) = unpack('C4',$addr[0]);

       getsockname SOCKET
	       Returns the packed sockaddr address of this end of the SOCKET
	       connection.

		   # An internet sockaddr
		   $sockaddr = 'S n a4 x8';
		   $mysockaddr = getsockname(S);
		   ($family, $port, $myaddr) =
				   unpack($sockaddr,$mysockaddr);

       getsockopt SOCKET,LEVEL,OPTNAME
	       Returns the socket option requested, or undefined if there is
	       an error.

       glob EXPR
	       Returns the value of EXPR with filename expansions such as a
	       shell would do.	This is the internal function implementing the
	       <*.*> operator.

       gmtime EXPR
	       Converts a time as returned by the time function to a 9-element
	       array with the time localized for the Greenwich timezone.
	       Typically used as follows:

		   ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
							   gmtime(time);

	       All array elements are numeric, and come straight out of a
	       struct tm.  In particular this means that $mon has the range
	       0..11 and $wday has the range 0..6.  If EXPR is omitted, does
	       gmtime(time()).

       goto LABEL

       goto EXPR

       goto &NAME
	       The goto-LABEL form finds the statement labeled with LABEL and
	       resumes execution there.	 It may not be used to go into any
	       construct that requires initialization, such as a subroutine or
	       a foreach loop.	It also can't be used to go into a construct
	       that is optimized away.	It can be used to go almost anywhere
	       else within the dynamic scope, including out of subroutines,
	       but it's usually better to use some other construct such as
	       last or die.  The author of Perl has never felt the need to use
	       this form of goto (in Perl, that is--C is another matter).

	       The goto-EXPR form expects a label name, whose scope will be
	       resolved dynamically.  This allows for computed gotos per
	       FORTRAN, but isn't necessarily recommended if you're optimizing
	       for maintainability:

		   goto ("FOO", "BAR", "GLARCH")[$i];

	       The goto-&NAME form is highly magical, and substitutes a call
	       to the named subroutine for the currently running subroutine.
	       This is used by AUTOLOAD subroutines that wish to load another
	       subroutine and then pretend that the other subroutine had been
	       called in the first place (except that any modifications to @_
	       in the current subroutine are propagated to the other
	       subroutine.)  After the goto, not even caller() will be able to
	       tell that this routine was called first.

       grep BLOCK LIST

       grep EXPR,LIST
	       Evaluates the BLOCK or EXPR for each element of LIST (locally
	       setting $_ to each element) and returns the list value
	       consisting of those elements for which the expression evaluated
	       to TRUE.	 In a scalar context, returns the number of times the
	       expression was TRUE.

		   @foo = grep(!/^#/, @bar);	# weed out comments

	       or equivalently,

		   @foo = grep {!/^#/} @bar;	# weed out comments

	       Note that, since $_ is a reference into the list value, it can
	       be used to modify the elements of the array.  While this is
	       useful and supported, it can cause bizarre results if the LIST
	       is not a named array.

       hex EXPR
	       Returns the decimal value of EXPR interpreted as an hex string.
	       (To interpret strings that might start with 0 or 0x see oct().)
	       If EXPR is omitted, uses $_.

       import  There is no built-in import() function.	It is merely an
	       ordinary method subroutine defined (or inherited) by modules
	       that wish to export names to another module.  The use()
	       function calls the import() method for the package used.	 See
	       also the use entry elsewhere in this documentthe perlmod
	       manpage.

       index STR,SUBSTR,POSITION

       index STR,SUBSTR
	       Returns the position of the first occurrence of SUBSTR in STR
	       at or after POSITION.  If POSITION is omitted, starts searching
	       from the beginning of the string.  The return value is based at
	       0, or whatever you've set the $[ variable to.  If the substring
	       is not found, returns one less than the base, ordinarily -1.

       int EXPR
	       Returns the integer portion of EXPR.  If EXPR is omitted, uses
	       $_.

       ioctl FILEHANDLE,FUNCTION,SCALAR
	       Implements the ioctl(2) function.  You'll probably have to say

		   require "ioctl.ph"; # probably /usr/local/lib/perl/ioctl.ph

	       first to get the correct function definitions.  If ioctl.ph
	       doesn't exist or doesn't have the correct definitions you'll
	       have to roll your own, based on your C header files such as
	       <sys/ioctl.h>.  (There is a Perl script called h2ph that comes
	       with the Perl kit which may help you in this.)  SCALAR will be
	       read and/or written depending on the FUNCTION--a pointer to the
	       string value of SCALAR will be passed as the third argument of
	       the actual ioctl call.  (If SCALAR has no string value but does
	       have a numeric value, that value will be passed rather than a
	       pointer to the string value.  To guarantee this to be TRUE, add
	       a 0 to the scalar before using it.)  The pack() and unpack()
	       functions are useful for manipulating the values of structures
	       used by ioctl().	 The following example sets the erase
	       character to DEL.

		   require 'ioctl.ph';
		   $sgttyb_t = "ccccs";		       # 4 chars and a short
		   if (ioctl(STDIN,$TIOCGETP,$sgttyb)) {
		       @ary = unpack($sgttyb_t,$sgttyb);
		       $ary[2] = 127;
		       $sgttyb = pack($sgttyb_t,@ary);
		       ioctl(STDIN,$TIOCSETP,$sgttyb)
			   ⎪⎪ die "Can't ioctl: $!";
		   }

	       The return value of ioctl (and fcntl) is as follows:

		       if OS returns:	       then Perl returns:
			   -1			 undefined value
			    0		       string "0 but true"
		       anything else		   that number

	       Thus Perl returns TRUE on success and FALSE on failure, yet you
	       can still easily determine the actual value returned by the
	       operating system:

		   ($retval = ioctl(...)) ⎪⎪ ($retval = -1);
		   printf "System returned %d\n", $retval;

       join EXPR,LIST
	       Joins the separate strings of LIST or ARRAY into a single
	       string with fields separated by the value of EXPR, and returns
	       the string.  Example:

		   $_ = join(':', $login,$passwd,$uid,$gid,$gcos,$home,$shell);

	       See the split entry in the perlfunc manpage.

       keys ASSOC_ARRAY
	       Returns a normal array consisting of all the keys of the named
	       associative array.  (In a scalar context, returns the number of
	       keys.)  The keys are returned in an apparently random order,
	       but it is the same order as either the values() or each()
	       function produces (given that the associative array has not
	       been modified).	Here is yet another way to print your
	       environment:

		   @keys = keys %ENV;
		   @values = values %ENV;
		   while ($#keys >= 0) {
		       print pop(@keys), '=', pop(@values), "\n";
		   }

	       or how about sorted by key:

		   foreach $key (sort(keys %ENV)) {
		       print $key, '=', $ENV{$key}, "\n";
		   }

       kill LIST
	       Sends a signal to a list of processes.  The first element of
	       the list must be the signal to send.  Returns the number of
	       processes successfully signaled.

		   $cnt = kill 1, $child1, $child2;
		   kill 9, @goners;

	       Unlike in the shell, in Perl if the SIGNAL is negative, it
	       kills process groups instead of processes.  (On System V, a
	       negative PROCESS number will also kill process groups, but
	       that's not portable.)  That means you usually want to use
	       positive not negative signals.  You may also use a signal name
	       in quotes.

       last LABEL

       last    The last command is like the break statement in C (as used in
	       loops); it immediately exits the loop in question.  If the
	       LABEL is omitted, the command refers to the innermost enclosing
	       loop.  The continue block, if any, is not executed:

		   line: while (<STDIN>) {
		       last line if /^$/;      # exit when done with header
		       ...
		   }

       lc EXPR Returns an lowercased version of EXPR.  This is the internal
	       function implementing the \L escape in double-quoted strings.

       lcfirst EXPR
	       Returns the value of EXPR with the first character lowercased.
	       This is the internal function implementing the \l escape in
	       double-quoted strings.

       length EXPR
	       Returns the length in characters of the value of EXPR.  If EXPR
	       is omitted, returns length of $_.

       link OLDFILE,NEWFILE
	       Creates a new filename linked to the old filename.  Returns 1
	       for success, 0 otherwise.

       listen SOCKET,QUEUESIZE
	       Does the same thing that the listen system call does.  Returns
	       TRUE if it succeeded, FALSE otherwise.  See example in the
	       perlipc manpage.

       local EXPR
	       In general, you should be using "my" instead of "local",
	       because it's faster and safer.  Format variables often use
	       "local" though, as do other variables whose current value must
	       be visible to called subroutines.  This is known as dynamic
	       scoping.	 Lexical scoping is done with "my", which works more
	       like C's auto declarations.

	       A local modifies the listed variables to be local to the
	       enclosing block, subroutine, eval or "do".  If more than one
	       value is listed, the list must be placed in parens.  All the
	       listed elements must be legal lvalues.  This operator works by
	       saving the current values of those variables in LIST on a
	       hidden stack and restoring them upon exiting the block,
	       subroutine or eval.  This means that called subroutines can
	       also reference the local variable, but not the global one.  The
	       LIST may be assigned to if desired, which allows you to
	       initialize your local variables.	 (If no initializer is given
	       for a particular variable, it is created with an undefined
	       value.)	Commonly this is used to name the parameters to a
	       subroutine.  Examples:

		   sub RANGEVAL {
		       local($min, $max, $thunk) = @_;
		       local $result = '';
		       local $i;

		       # Presumably $thunk makes reference to $i

		       for ($i = $min; $i < $max; $i++) {
			   $result .= eval $thunk;
		       }

		       $result;
		   }

		   if ($sw eq '-v') {
		       # init local array with global array
		       local @ARGV = @ARGV;
		       unshift(@ARGV,'echo');
		       system @ARGV;
		   }
		   # @ARGV restored

		   # temporarily add to digits associative array
		   if ($base12) {
		       # (NOTE: not claiming this is efficient!)
		       local(%digits) = (%digits,'t',10,'e',11);
		       parse_num();
		   }

	       Note that local() is a run-time command, and so gets executed
	       every time through a loop.  In Perl 4 it used more stack
	       storage each time until the loop was exited.  Perl 5 reclaims
	       the space each time through, but it's still more efficient to
	       declare your variables outside the loop.

	       A local is simply a modifier on an lvalue expression.  When you
	       assign to a localized EXPR, the local doesn't change whether
	       EXPR is viewed as a scalar or an array.	So

		   local($foo) = <STDIN>;
		   local @FOO = <STDIN>;

	       both supply a list context to the righthand side, while

		   local $foo = <STDIN>;

	       supplies a scalar context.

       localtime EXPR
	       Converts a time as returned by the time function to a 9-element
	       array with the time analyzed for the local timezone.  Typically
	       used as follows:

		   ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
							       localtime(time);

	       All array elements are numeric, and come straight out of a
	       struct tm.  In particular this means that $mon has the range
	       0..11 and $wday has the range 0..6.  If EXPR is omitted, does
	       localtime(time).

	       In a scalar context, prints out the ctime(3) value:

		   $now_string = localtime;  # e.g. "Thu Oct 13 04:54:34 1994"

	       See also the timelocal entry in the perlmod manpage and the
	       strftime(3) function available via the POSIX modulie.

       log EXPR
	       Returns logarithm (base e) of EXPR.  If EXPR is omitted,
	       returns log of $_.

       lstat FILEHANDLE

       lstat EXPR
	       Does the same thing as the stat() function, but stats a
	       symbolic link instead of the file the symbolic link points to.
	       If symbolic links are unimplemented on your system, a normal
	       stat() is done.

       m//     The match operator.  See the perlop manpage.

       map BLOCK LIST

       map EXPR,LIST
	       Evaluates the BLOCK or EXPR for each element of LIST (locally
	       setting $_ to each element) and returns the list value composed
	       of the results of each such evaluation.	Evaluates BLOCK or
	       EXPR in a list context, so each element of LIST may produce
	       zero, one, or more elements in the returned value.

		   @chars = map(chr, @nums);

	       translates a list of numbers to the corresponding characters.
	       And

		   %hash = map {&key($_), $_} @array;

	       is just a funny way to write

		   %hash = ();
		   foreach $_ (@array) {
		       $hash{&key($_)} = $_;
		   }

       mkdir FILENAME,MODE
	       Creates the directory specified by FILENAME, with permissions
	       specified by MODE (as modified by umask).  If it succeeds it
	       returns 1, otherwise it returns 0 and sets $! (errno).

       msgctl ID,CMD,ARG
	       Calls the System V IPC function msgctl.	If CMD is &IPC_STAT,
	       then ARG must be a variable which will hold the returned
	       msqid_ds structure.  Returns like ioctl: the undefined value
	       for error, "0 but true" for zero, or the actual return value
	       otherwise.

       msgget KEY,FLAGS
	       Calls the System V IPC function msgget.	Returns the message
	       queue id, or the undefined value if there is an error.

       msgsnd ID,MSG,FLAGS
	       Calls the System V IPC function msgsnd to send the message MSG
	       to the message queue ID.	 MSG must begin with the long integer
	       message type, which may be created with pack("L", $type).
	       Returns TRUE if successful, or FALSE if there is an error.

       msgrcv ID,VAR,SIZE,TYPE,FLAGS
	       Calls the System V IPC function msgrcv to receive a message
	       from message queue ID into variable VAR with a maximum message
	       size of SIZE.  Note that if a message is received, the message
	       type will be the first thing in VAR, and the maximum length of
	       VAR is SIZE plus the size of the message type.  Returns TRUE if
	       successful, or FALSE if there is an error.

       my EXPR A "my" declares the listed variables to be local (lexically) to
	       the enclosing block, subroutine, eval or "do".  If more than
	       one value is listed, the list must be placed in parens.	All
	       the listed elements must be legal lvalues.  Only alphanumeric
	       identifiers may be lexically scoped--magical builtins like $/
	       must be localized with "local" instead.	In particular, you're
	       not allowed to say

		   my $_;      # Illegal.

	       Unlike the "local" declaration, variables declared with "my"
	       are totally hidden from the outside world, including any called
	       subroutines (even if it's the same subroutine--every call gets
	       its own copy).

	       (An eval(), however, can see the lexical variables of the scope
	       it is being evaluated in so long as the names aren't hidden by
	       declarations within the eval() itself.  See the perlref
	       manpage.)

	       The EXPR may be assigned to if desired, which allows you to
	       initialize your variables.  (If no initializer is given for a
	       particular variable, it is created with an undefined value.)
	       Commonly this is used to name the parameters to a subroutine.
	       Examples:

		   sub RANGEVAL {
		       my($min, $max, $thunk) = @_;
		       my $result = '';
		       my $i;

		       # Presumably $thunk makes reference to $i

		       for ($i = $min; $i < $max; $i++) {
			   $result .= eval $thunk;
		       }

		       $result;
		   }

		   if ($sw eq '-v') {
		       # init my array with global array
		       my @ARGV = @ARGV;
		       unshift(@ARGV,'echo');
		       system @ARGV;
		   }
		   # Outer @ARGV again visible

	       The "my" is simply a modifier on something you might assign to.
	       So when you do assign to the EXPR, the "my" doesn't change
	       whether EXPR is viewed as a scalar or an array.	So

		   my ($foo) = <STDIN>;
		   my @FOO = <STDIN>;

	       both supply a list context to the righthand side, while

		   my $foo = <STDIN>;

	       supplies a scalar context.  But the following only declares one
	       variable:

		   my $foo, $bar = 1;

	       That has the same effect as

		   my $foo;
		   $bar = 1;

	       The declared variable is not introduced (is not visible) until
	       after the current statement.  Thus,

		   my $x = $x;

	       can be used to initialize the new $x with the value of the old
	       $x, and the expression

		   my $x = 123 and $x == 123

	       is false unless the old $x happened to have the value 123.

	       Some users may wish to encourage the use of lexically scoped
	       variables.  As an aid to catching implicit references to
	       package variables, if you say

		   use strict 'vars';

	       then any variable reference from there to the end of the
	       enclosing block must either refer to a lexical variable, or
	       must be fully qualified with the package name.  A compilation
	       error results otherwise.	 An inner block may countermand this
	       with "no strict 'vars'".

       next LABEL

       next    The next command is like the continue statement in C; it starts
	       the next iteration of the loop:

		   line: while (<STDIN>) {
		       next line if /^#/;      # discard comments
		       ...
		   }

	       Note that if there were a continue block on the above, it would
	       get executed even on discarded lines.  If the LABEL is omitted,
	       the command refers to the innermost enclosing loop.

       no Module LIST
	       See the "use" function, which "no" is the opposite of.

       oct EXPR
	       Returns the decimal value of EXPR interpreted as an octal
	       string.	(If EXPR happens to start off with 0x, interprets it
	       as a hex string instead.)  The following will handle decimal,
	       octal, and hex in the standard Perl or C notation:

		   $val = oct($val) if $val =~ /^0/;

	       If EXPR is omitted, uses $_.

       open FILEHANDLE,EXPR

       open FILEHANDLE
	       Opens the file whose filename is given by EXPR, and associates
	       it with FILEHANDLE.  If FILEHANDLE is an expression, its value
	       is used as the name of the real filehandle wanted.  If EXPR is
	       omitted, the scalar variable of the same name as the FILEHANDLE
	       contains the filename.  If the filename begins with "<" or
	       nothing, the file is opened for input.  If the filename begins
	       with ">", the file is opened for output.	 If the filename
	       begins with ">>", the file is opened for appending.  (You can
	       put a '+' in front of the '>' or '<' to indicate that you want
	       both read and write access to the file.)	 If the filename
	       begins with "⎪", the filename is interpreted as a command to
	       which output is to be piped, and if the filename ends with a
	       "⎪", the filename is interpreted as command which pipes input
	       to us.  (You may not have a command that pipes both in and
	       out.)  Opening '-' opens STDIN and opening '>-' opens STDOUT.
	       Open returns non-zero upon success, the undefined value
	       otherwise.  If the open involved a pipe, the return value
	       happens to be the pid of the subprocess.	 Examples:

		   $ARTICLE = 100;
		   open ARTICLE or die "Can't find article $ARTICLE: $!\n";
		   while (<ARTICLE>) {...

		   open(LOG, '>>/usr/spool/news/twitlog'); # (log is reserved)

		   open(article, "caesar <$article ⎪");	   # decrypt article

		   open(extract, "⎪sort >/tmp/Tmp$$");	   # $$ is our process id

		   # process argument list of files along with any includes

		   foreach $file (@ARGV) {
		       process($file, 'fh00');
		   }

		   sub process {
		       local($filename, $input) = @_;
		       $input++;	       # this is a string increment
		       unless (open($input, $filename)) {
			   print STDERR "Can't open $filename: $!\n";
			   return;
		       }

		       while (<$input>) {	       # note use of indirection
			   if (/^#include "(.*)"/) {
			       process($1, $input);
			       next;
			   }
			   ...	       # whatever
		       }
		   }

	       You may also, in the Bourne shell tradition, specify an EXPR
	       beginning with ">&", in which case the rest of the string is
	       interpreted as the name of a filehandle (or file descriptor, if
	       numeric) which is to be duped and opened.  You may use & after
	       >, >>, <, +>, +>> and +<.  The mode you specify should match
	       the mode of the original filehandle.  Here is a script that
	       saves, redirects, and restores STDOUT and STDERR:

		   #!/usr/bin/perl
		   open(SAVEOUT, ">&STDOUT");
		   open(SAVEERR, ">&STDERR");

		   open(STDOUT, ">foo.out") ⎪⎪ die "Can't redirect stdout";
		   open(STDERR, ">&STDOUT") ⎪⎪ die "Can't dup stdout";

		   select(STDERR); $⎪ = 1;     # make unbuffered
		   select(STDOUT); $⎪ = 1;     # make unbuffered

		   print STDOUT "stdout 1\n";  # this works for
		   print STDERR "stderr 1\n";  # subprocesses too

		   close(STDOUT);
		   close(STDERR);

		   open(STDOUT, ">&SAVEOUT");
		   open(STDERR, ">&SAVEERR");

		   print STDOUT "stdout 2\n";
		   print STDERR "stderr 2\n";

	       If you specify "<&=N", where N is a number, then Perl will do
	       an equivalent of C's fdopen() of that file descriptor.  For
	       example:

		   open(FILEHANDLE, "<&=$fd")

	       If you open a pipe on the command "-", i.e. either "⎪-" or
	       "-⎪", then there is an implicit fork done, and the return value
	       of open is the pid of the child within the parent process, and
	       0 within the child process.  (Use defined($pid) to determine
	       whether the open was successful.)  The filehandle behaves
	       normally for the parent, but i/o to that filehandle is piped
	       from/to the STDOUT/STDIN of the child process.  In the child
	       process the filehandle isn't opened--i/o happens from/to the
	       new STDOUT or STDIN.  Typically this is used like the normal
	       piped open when you want to exercise more control over just how
	       the pipe command gets executed, such as when you are running
	       setuid, and don't want to have to scan shell commands for
	       metacharacters.	The following pairs are more or less
	       equivalent:

		   open(FOO, "⎪tr '[a-z]' '[A-Z]'");
		   open(FOO, "⎪-") ⎪⎪ exec 'tr', '[a-z]', '[A-Z]';

		   open(FOO, "cat -n '$file'⎪");
		   open(FOO, "-⎪") ⎪⎪ exec 'cat', '-n', $file;

	       Explicitly closing any piped filehandle causes the parent
	       process to wait for the child to finish, and returns the status
	       value in $?.  Note: on any operation which may do a fork,
	       unflushed buffers remain unflushed in both processes, which
	       means you may need to set $⎪ to avoid duplicate output.

	       The filename that is passed to open will have leading and
	       trailing whitespace deleted.  In order to open a file with
	       arbitrary weird characters in it, it's necessary to protect any
	       leading and trailing whitespace thusly:

		       $file =~ s#^(\s)#./$1#;
		       open(FOO, "< $file\0");

       opendir DIRHANDLE,EXPR
	       Opens a directory named EXPR for processing by readdir(),
	       telldir(), seekdir(), rewinddir() and closedir().  Returns TRUE
	       if successful.  DIRHANDLEs have their own namespace separate
	       from FILEHANDLEs.

       ord EXPR
	       Returns the numeric ascii value of the first character of EXPR.
	       If EXPR is omitted, uses $_.

       pack TEMPLATE,LIST
	       Takes an array or list of values and packs it into a binary
	       structure, returning the string containing the structure.  The
	       TEMPLATE is a sequence of characters that give the order and
	       type of values, as follows:

		   A   An ascii string, will be space padded.
		   a   An ascii string, will be null padded.
		   b   A bit string (ascending bit order, like vec()).
		   B   A bit string (descending bit order).
		   h   A hex string (low nybble first).
		   H   A hex string (high nybble first).

		   c   A signed char value.
		   C   An unsigned char value.
		   s   A signed short value.
		   S   An unsigned short value.
		   i   A signed integer value.
		   I   An unsigned integer value.
		   l   A signed long value.
		   L   An unsigned long value.

		   n   A short in "network" order.
		   N   A long in "network" order.
		   v   A short in "VAX" (little-endian) order.
		   V   A long in "VAX" (little-endian) order.

		   f   A single-precision float in the native format.
		   d   A double-precision float in the native format.

		   p   A pointer to a null-terminated string.
		   P   A pointer to a structure (fixed-length string).

		   u   A uuencoded string.

		   x   A null byte.
		   X   Back up a byte.
		   @   Null fill to absolute position.

	       Each letter may optionally be followed by a number which gives
	       a repeat count.	With all types except "a", "A", "b", "B", "h"
	       and "H", and "P" the pack function will gobble up that many
	       values from the LIST.  A * for the repeat count means to use
	       however many items are left.  The "a" and "A" types gobble just
	       one value, but pack it as a string of length count, padding
	       with nulls or spaces as necessary.  (When unpacking, "A" strips
	       trailing spaces and nulls, but "a" does not.)  Likewise, the
	       "b" and "B" fields pack a string that many bits long.  The "h"
	       and "H" fields pack a string that many nybbles long.  The "P"
	       packs a pointer to a structure of the size indicated by the
	       length.	Real numbers (floats and doubles) are in the native
	       machine format only; due to the multiplicity of floating
	       formats around, and the lack of a standard "network"
	       representation, no facility for interchange has been made.
	       This means that packed floating point data written on one
	       machine may not be readable on another - even if both use IEEE
	       floating point arithmetic (as the endian-ness of the memory
	       representation is not part of the IEEE spec).  Note that Perl
	       uses doubles internally for all numeric calculation, and
	       converting from double into float and thence back to double
	       again will lose precision (i.e.	unpack("f", pack("f", $foo))
	       will not in general equal $foo).

	       Examples:

		   $foo = pack("cccc",65,66,67,68);
		   # foo eq "ABCD"
		   $foo = pack("c4",65,66,67,68);
		   # same thing

		   $foo = pack("ccxxcc",65,66,67,68);
		   # foo eq "AB\0\0CD"

		   $foo = pack("s2",1,2);
		   # "\1\0\2\0" on little-endian
		   # "\0\1\0\2" on big-endian

		   $foo = pack("a4","abcd","x","y","z");
		   # "abcd"

		   $foo = pack("aaaa","abcd","x","y","z");
		   # "axyz"

		   $foo = pack("a14","abcdefg");
		   # "abcdefg\0\0\0\0\0\0\0"

		   $foo = pack("i9pl", gmtime);
		   # a real struct tm (on my system anyway)

		   sub bintodec {
		       unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
		   }

	       The same template may generally also be used in the unpack
	       function.

       pipe READHANDLE,WRITEHANDLE
	       Opens a pair of connected pipes like the corresponding system
	       call.  Note that if you set up a loop of piped processes,
	       deadlock can occur unless you are very careful.	In addition,
	       note that Perl's pipes use stdio buffering, so you may need to
	       set $⎪ to flush your WRITEHANDLE after each command, depending
	       on the application.

       pop ARRAY
	       Pops and returns the last value of the array, shortening the
	       array by 1.  Has a similar effect to

		   $tmp = $ARRAY[$#ARRAY--];

	       If there are no elements in the array, returns the undefined
	       value.

       pos SCALAR
	       Returns the offset of where the last m//g search left off for
	       the variable in question.  May be modified to change that
	       offset.

       print FILEHANDLE LIST

       print LIST

       print   Prints a string or a comma-separated list of strings.  Returns
	       non-zero if successful.	FILEHANDLE may be a scalar variable
	       name, in which case the variable contains the name of the
	       filehandle, thus introducing one level of indirection.  (NOTE:
	       If FILEHANDLE is a variable and the next token is a term, it
	       may be misinterpreted as an operator unless you interpose a +
	       or put parens around the arguments.)  If FILEHANDLE is omitted,
	       prints by default to standard output (or to the last selected
	       output channel--see select()).  If LIST is also omitted, prints
	       $_ to STDOUT.  To set the default output channel to something
	       other than STDOUT use the select operation.  Note that, because
	       print takes a LIST, anything in the LIST is evaluated in a list
	       context, and any subroutine that you call will have one or more
	       of its expressions evaluated in a list context.	Also be
	       careful not to follow the print keyword with a left parenthesis
	       unless you want the corresponding right parenthesis to
	       terminate the arguments to the print--interpose a + or put
	       parens around all the arguments.

       printf FILEHANDLE LIST

       printf LIST
	       Equivalent to a "print FILEHANDLE sprintf(LIST)".  The first
	       argument of the list will be interpreted as the printf format.

       push ARRAY,LIST
	       Treats ARRAY as a stack, and pushes the values of LIST onto the
	       end of ARRAY.  The length of ARRAY increases by the length of
	       LIST.  Has the same effect as

		   for $value (LIST) {
		       $ARRAY[++$#ARRAY] = $value;
		   }

	       but is more efficient.  Returns the new number of elements in
	       the array.

       q/STRING/

       qq/STRING/

       qx/STRING/

       qw/STRING/
	       Generalized quotes.  See the perlop manpage.

       quotemeta EXPR
	       Returns the value of EXPR with with all regular expression
	       metacharacters backslashed.  This is the internal function
	       implementing the \Q escape in double-quoted strings.

       rand EXPR

       rand    Returns a random fractional number between 0 and the value of
	       EXPR.  (EXPR should be positive.)  If EXPR is omitted, returns
	       a value between 0 and 1.	 This function produces repeatable
	       sequences unless srand() is invoked.  See also srand().

	       (Note: if your rand function consistently returns numbers that
	       are too large or too small, then your version of Perl was
	       probably compiled with the wrong number of RANDBITS.  As a
	       workaround, you can usually multiply EXPR by the correct power
	       of 2 to get the range you want.	This will make your script
	       unportable, however.  It's better to recompile if you can.)

       read FILEHANDLE,SCALAR,LENGTH,OFFSET

       read FILEHANDLE,SCALAR,LENGTH
	       Attempts to read LENGTH bytes of data into variable SCALAR from
	       the specified FILEHANDLE.  Returns the number of bytes actually
	       read, or undef if there was an error.  SCALAR will be grown or
	       shrunk to the length actually read.  An OFFSET may be specified
	       to place the read data at some other place than the beginning
	       of the string.  This call is actually implemented in terms of
	       stdio's fread call.  To get a true read system call, see
	       sysread().

       readdir DIRHANDLE
	       Returns the next directory entry for a directory opened by
	       opendir().  If used in a list context, returns all the rest of
	       the entries in the directory.  If there are no more entries,
	       returns an undefined value in a scalar context or a null list
	       in a list context.

       readlink EXPR
	       Returns the value of a symbolic link, if symbolic links are
	       implemented.  If not, gives a fatal error.  If there is some
	       system error, returns the undefined value and sets $! (errno).
	       If EXPR is omitted, uses $_.

       recv SOCKET,SCALAR,LEN,FLAGS
	       Receives a message on a socket.	Attempts to receive LENGTH
	       bytes of data into variable SCALAR from the specified SOCKET
	       filehandle.  Actually does a C recvfrom(), so that it can
	       returns the address of the sender.  Returns the undefined value
	       if there's an error.  SCALAR will be grown or shrunk to the
	       length actually read.  Takes the same flags as the system call
	       of the same name.

       redo LABEL

       redo    The redo command restarts the loop block without evaluating the
	       conditional again.  The continue block, if any, is not
	       executed.  If the LABEL is omitted, the command refers to the
	       innermost enclosing loop.  This command is normally used by
	       programs that want to lie to themselves about what was just
	       input:

		   # a simpleminded Pascal comment stripper
		   # (warning: assumes no { or } in strings)
		   line: while (<STDIN>) {
		       while (s⎪({.*}.*){.*}⎪$1 ⎪) {}
		       s⎪{.*}⎪ ⎪;
		       if (s⎪{.*⎪ ⎪) {
			   $front = $_;
			   while (<STDIN>) {
			       if (/}/) {      # end of comment?
				   s⎪^⎪$front{⎪;
				   redo line;
			       }
			   }
		       }
		       print;
		   }

       ref EXPR
	       Returns a TRUE value if EXPR is a reference, FALSE otherwise.
	       The value returned depends on the type of thing the reference
	       is a reference to.  Builtin types include:

		   REF
		   SCALAR
		   ARRAY
		   HASH
		   CODE
		   GLOB

	       If the referenced object has been blessed into a package, then
	       that package name is returned instead.  You can think of ref()
	       as a typeof() operator.

		   if (ref($r) eq "HASH") {
		       print "r is a reference to an associative array.\n";
		   }
		   if (!ref ($r) {
		       print "r is not a reference at all.\n";
		   }

	       See also the perlref manpage.

       rename OLDNAME,NEWNAME
	       Changes the name of a file.  Returns 1 for success, 0
	       otherwise.  Will not work across filesystem boundaries.

       require EXPR

       require Demands some semantics specified by EXPR, or by $_ if EXPR is
	       not supplied.  If EXPR is numeric, demands that the current
	       version of Perl ($] or $PERL_VERSION) be equal or greater than
	       EXPR.

	       Otherwise, demands that a library file be included if it hasn't
	       already been included.  The file is included via the do-FILE
	       mechanism, which is essentially just a variety of eval().  Has
	       semantics similar to the following subroutine:

		   sub require {
		       local($filename) = @_;
		       return 1 if $INC{$filename};
		       local($realfilename,$result);
		       ITER: {
			   foreach $prefix (@INC) {
			       $realfilename = "$prefix/$filename";
			       if (-f $realfilename) {
				   $result = do $realfilename;
				   last ITER;
			       }
			   }
			   die "Can't find $filename in \@INC";
		       }
		       die $@ if $@;
		       die "$filename did not return true value" unless $result;
		       $INC{$filename} = $realfilename;
		       $result;
		   }

	       Note that the file will not be included twice under the same
	       specified name.	The file must return TRUE as the last
	       statement to indicate successful execution of any
	       initialization code, so it's customary to end such a file with
	       "1;" unless you're sure it'll return TRUE otherwise.  But it's
	       better just to put the "1;", in case you add more statements.

	       If EXPR is a bare word, the require assumes a ".pm" extension
	       for you, to make it easy to load standard modules.  This form
	       of loading of modules does not risk altering your namespace.

	       For a yet-more-powerful import facility, see the the use()
	       entry elsewhere in this documentthe perlmod manpage.

       reset EXPR

       reset   Generally used in a continue block at the end of a loop to
	       clear variables and reset ?? searches so that they work again.
	       The expression is interpreted as a list of single characters
	       (hyphens allowed for ranges).  All variables and arrays
	       beginning with one of those letters are reset to their pristine
	       state.  If the expression is omitted, one-match searches
	       (?pattern?) are reset to match again.  Only resets variables or
	       searches in the current package.	 Always returns 1.  Examples:

		   reset 'X';	       # reset all X variables
		   reset 'a-z';	       # reset lower case variables
		   reset;	       # just reset ?? searches

	       Resetting "A-Z" is not recommended since you'll wipe out your
	       ARGV and ENV arrays.  Only resets package variables--lexical
	       variables are unaffected, but they clean themselves up on scope
	       exit anyway, so anymore you probably want to use them instead.
	       See the my entry elsewhere in this document.

       return LIST
	       Returns from a subroutine or eval with the value specified.
	       (Note that in the absence of a return a subroutine or eval will
	       automatically return the value of the last expression
	       evaluated.)

       reverse LIST
	       In a list context, returns a list value consisting of the
	       elements of LIST in the opposite order.	In a scalar context,
	       returns a string value consisting of the bytes of the first
	       element of LIST in the opposite order.

       rewinddir DIRHANDLE
	       Sets the current position to the beginning of the directory for
	       the readdir() routine on DIRHANDLE.

       rindex STR,SUBSTR,POSITION

       rindex STR,SUBSTR
	       Works just like index except that it returns the position of
	       the LAST occurrence of SUBSTR in STR.  If POSITION is
	       specified, returns the last occurrence at or before that
	       position.

       rmdir FILENAME
	       Deletes the directory specified by FILENAME if it is empty.  If
	       it succeeds it returns 1, otherwise it returns 0 and sets $!
	       (errno).	 If FILENAME is omitted, uses $_.

       s///    The substitution operator.  See the perlop manpage.

       scalar EXPR
	       Forces EXPR to be interpreted in a scalar context and returns
	       the value of EXPR.

       seek FILEHANDLE,POSITION,WHENCE
	       Randomly positions the file pointer for FILEHANDLE, just like
	       the fseek() call of stdio.  FILEHANDLE may be an expression
	       whose value gives the name of the filehandle.  The values for
	       WHENCE are 0 to set the file pointer to POSITION, 1 to set the
	       it to current plus POSITION, and 2 to set it to EOF plus
	       offset.	You may use the values SEEK_SET, SEEK_CUR, and
	       SEEK_END for this is using the POSIX module.  Returns 1 upon
	       success, 0 otherwise.

       seekdir DIRHANDLE,POS
	       Sets the current position for the readdir() routine on
	       DIRHANDLE.  POS must be a value returned by telldir().  Has the
	       same caveats about possible directory compaction as the
	       corresponding system library routine.

       select FILEHANDLE

       select  Returns the currently selected filehandle.  Sets the current
	       default filehandle for output, if FILEHANDLE is supplied.  This
	       has two effects: first, a write or a print without a filehandle
	       will default to this FILEHANDLE.	 Second, references to
	       variables related to output will refer to this output channel.
	       For example, if you have to set the top of form format for more
	       than one output channel, you might do the following:

		   select(REPORT1);
		   $^ = 'report1_top';
		   select(REPORT2);
		   $^ = 'report2_top';

	       FILEHANDLE may be an expression whose value gives the name of
	       the actual filehandle.  Thus:

		   $oldfh = select(STDERR); $⎪ = 1; select($oldfh);

	       With Perl 5, filehandles are objects with methods, and the last
	       example is preferably written

		   use FileHandle;
		   STDERR->autoflush(1);

       select RBITS,WBITS,EBITS,TIMEOUT
	       This calls the select system(2) call with the bitmasks
	       specified, which can be constructed using fileno() and vec(),
	       along these lines:

		   $rin = $win = $ein = '';
		   vec($rin,fileno(STDIN),1) = 1;
		   vec($win,fileno(STDOUT),1) = 1;
		   $ein = $rin ⎪ $win;

	       If you want to select on many filehandles you might wish to
	       write a subroutine:

		   sub fhbits {
		       local(@fhlist) = split(' ',$_[0]);
		       local($bits);
		       for (@fhlist) {
			   vec($bits,fileno($_),1) = 1;
		       }
		       $bits;
		   }
		   $rin = &fhbits('STDIN TTY SOCK');

	       The usual idiom is:

		   ($nfound,$timeleft) =
		     select($rout=$rin, $wout=$win, $eout=$ein, $timeout);

	       or to block until something becomes ready:

		   $nfound = select($rout=$rin, $wout=$win, $eout=$ein, undef);

	       Any of the bitmasks can also be undef.  The timeout, if
	       specified, is in seconds, which may be fractional.  Note: not
	       all implementations are capable of returning the $timeleft.  If
	       not, they always return $timeleft equal to the supplied
	       $timeout.

	       You can effect a 250 microsecond sleep this way:

		   select(undef, undef, undef, 0.25);

       semctl ID,SEMNUM,CMD,ARG
	       Calls the System V IPC function semctl.	If CMD is &IPC_STAT or
	       &GETALL, then ARG must be a variable which will hold the
	       returned semid_ds structure or semaphore value array.  Returns
	       like ioctl: the undefined value for error, "0 but true" for
	       zero, or the actual return value otherwise.

       semget KEY,NSEMS,FLAGS
	       Calls the System V IPC function semget.	Returns the semaphore
	       id, or the undefined value if there is an error.

       semop KEY,OPSTRING
	       Calls the System V IPC function semop to perform semaphore
	       operations such as signaling and waiting.  OPSTRING must be a
	       packed array of semop structures.  Each semop structure can be
	       generated with pack("sss", $semnum, $semop, $semflag).  The
	       number of semaphore operations is implied by the length of
	       OPSTRING.  Returns TRUE if successful, or FALSE if there is an
	       error.  As an example, the following code waits on semaphore
	       $semnum of semaphore id $semid:

		   $semop = pack("sss", $semnum, -1, 0);
		   die "Semaphore trouble: $!\n" unless semop($semid, $semop);

	       To signal the semaphore, replace "-1" with "1".

       send SOCKET,MSG,FLAGS,TO

       send SOCKET,MSG,FLAGS
	       Sends a message on a socket.  Takes the same flags as the
	       system call of the same name.  On unconnected sockets you must
	       specify a destination to send TO, in which case it does a C
	       sendto().  Returns the number of characters sent, or the
	       undefined value if there is an error.

       setpgrp PID,PGRP
	       Sets the current process group for the specified PID, 0 for the
	       current process.	 Will produce a fatal error if used on a
	       machine that doesn't implement setpgrp(2).

       setpriority WHICH,WHO,PRIORITY
	       Sets the current priority for a process, a process group, or a
	       user.  (See setpriority(2).)  Will produce a fatal error if
	       used on a machine that doesn't implement setpriority(2).

       setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
	       Sets the socket option requested.  Returns undefined if there
	       is an error.  OPTVAL may be specified as undef if you don't
	       want to pass an argument.

       shift ARRAY

       shift   Shifts the first value of the array off and returns it,
	       shortening the array by 1 and moving everything down.  If there
	       are no elements in the array, returns the undefined value.  If
	       ARRAY is omitted, shifts the @ARGV array in the main program,
	       and the @_ array in subroutines.	 (This is determined
	       lexically.)  See also unshift(), push(), and pop().  Shift()
	       and unshift() do the same thing to the left end of an array
	       that push() and pop() do to the right end.

       shmctl ID,CMD,ARG
	       Calls the System V IPC function shmctl.	If CMD is &IPC_STAT,
	       then ARG must be a variable which will hold the returned
	       shmid_ds structure.  Returns like ioctl: the undefined value
	       for error, "0 but true" for zero, or the actual return value
	       otherwise.

       shmget KEY,SIZE,FLAGS
	       Calls the System V IPC function shmget.	Returns the shared
	       memory segment id, or the undefined value if there is an error.

       shmread ID,VAR,POS,SIZE

       shmwrite ID,STRING,POS,SIZE
	       Reads or writes the System V shared memory segment ID starting
	       at position POS for size SIZE by attaching to it, copying
	       in/out, and detaching from it.  When reading, VAR must be a
	       variable which will hold the data read.	When writing, if
	       STRING is too long, only SIZE bytes are used; if STRING is too
	       short, nulls are written to fill out SIZE bytes.	 Return TRUE
	       if successful, or FALSE if there is an error.

       shutdown SOCKET,HOW
	       Shuts down a socket connection in the manner indicated by HOW,
	       which has the same interpretation as in the system call of the
	       same name.

       sin EXPR
	       Returns the sine of EXPR (expressed in radians).	 If EXPR is
	       omitted, returns sine of $_.

       sleep EXPR

       sleep   Causes the script to sleep for EXPR seconds, or forever if no
	       EXPR.  May be interrupted by sending the process a SIGALRM.
	       Returns the number of seconds actually slept.  You probably
	       cannot mix alarm() and sleep() calls, since sleep() is often
	       implemented using alarm().

	       On some older systems, it may sleep up to a full second less
	       than what you requested, depending on how it counts seconds.
	       Most modern systems always sleep the full amount.

       socket SOCKET,DOMAIN,TYPE,PROTOCOL
	       Opens a socket of the specified kind and attaches it to
	       filehandle SOCKET.  DOMAIN, TYPE and PROTOCOL are specified the
	       same as for the system call of the same name.  You should "use
	       Socket;" first to get the proper definitions imported.  See the
	       example in the perlipc manpage.

       socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
	       Creates an unnamed pair of sockets in the specified domain, of
	       the specified type.  DOMAIN, TYPE and PROTOCOL are specified
	       the same as for the system call of the same name.  If
	       unimplemented, yields a fatal error.  Returns TRUE if
	       successful.

       sort SUBNAME LIST

       sort BLOCK LIST

       sort LIST
	       Sorts the LIST and returns the sorted list value.  Nonexistent
	       values of arrays are stripped out.  If SUBNAME or BLOCK is
	       omitted, sorts in standard string comparison order.  If SUBNAME
	       is specified, it gives the name of a subroutine that returns an
	       integer less than, equal to, or greater than 0, depending on
	       how the elements of the array are to be ordered.	 (The <=> and
	       cmp operators are extremely useful in such routines.)  SUBNAME
	       may be a scalar variable name, in which case the value provides
	       the name of the subroutine to use.  In place of a SUBNAME, you
	       can provide a BLOCK as an anonymous, in-line sort subroutine.

	       In the interests of efficiency the normal calling code for
	       subroutines is bypassed, with the following effects: the
	       subroutine may not be a recursive subroutine, and the two
	       elements to be compared are passed into the subroutine not via
	       @_ but as $a and $b (see example below).	 They are passed by
	       reference, so don't modify $a and $b.

	       Examples:

		   # sort lexically
		   @articles = sort @files;

		   # same thing, but with explicit sort routine
		   @articles = sort {$a cmp $b} @files;

		   # same thing in reversed order
		   @articles = sort {$b cmp $a} @files;

		   # sort numerically ascending
		   @articles = sort {$a <=> $b} @files;

		   # sort numerically descending
		   @articles = sort {$b <=> $a} @files;

		   # sort using explicit subroutine name
		   sub byage {
		       $age{$a} <=> $age{$b};  # presuming integers
		   }
		   @sortedclass = sort byage @class;

		   sub backwards { $b cmp $a; }
		   @harry = ('dog','cat','x','Cain','Abel');
		   @george = ('gone','chased','yz','Punished','Axed');
		   print sort @harry;
			   # prints AbelCaincatdogx
		   print sort backwards @harry;
			   # prints xdogcatCainAbel
		   print sort @george, 'to', @harry;
			   # prints AbelAxedCainPunishedcatchaseddoggonetoxyz

       splice ARRAY,OFFSET,LENGTH,LIST

       splice ARRAY,OFFSET,LENGTH

       splice ARRAY,OFFSET
	       Removes the elements designated by OFFSET and LENGTH from an
	       array, and replaces them with the elements of LIST, if any.
	       Returns the elements removed from the array.  The array grows
	       or shrinks as necessary.	 If LENGTH is omitted, removes
	       everything from OFFSET onward.  The following equivalencies
	       hold (assuming $[ == 0):

		   push(@a,$x,$y)      splice(@a,$#a+1,0,$x,$y)
		   pop(@a)	       splice(@a,-1)
		   shift(@a)	       splice(@a,0,1)
		   unshift(@a,$x,$y)   splice(@a,0,0,$x,$y)
		   $a[$x] = $y	       splice(@a,$x,1,$y);

	       Example, assuming array lengths are passed before arrays:

		   sub aeq {   # compare two list values
		       local(@a) = splice(@_,0,shift);
		       local(@b) = splice(@_,0,shift);
		       return 0 unless @a == @b;       # same len?
		       while (@a) {
			   return 0 if pop(@a) ne pop(@b);
		       }
		       return 1;
		   }
		   if (&aeq($len,@foo[1..$len],0+@bar,@bar)) { ... }

       split /PATTERN/,EXPR,LIMIT

       split /PATTERN/,EXPR

       split /PATTERN/

       split   Splits a string into an array of strings, and returns it.

	       If not in a list context, returns the number of fields found
	       and splits into the @_ array.  (In a list context, you can
	       force the split into @_ by using ?? as the pattern delimiters,
	       but it still returns the array value.)  The use of implicit
	       split to @_ is deprecated, however.

	       If EXPR is omitted, splits the $_ string.  If PATTERN is also
	       omitted, splits on whitespace (after skipping any leading
	       whitespace).  Anything matching PATTERN is taken to be a
	       delimiter separating the fields.	 (Note that the delimiter may
	       be longer than one character.)  If LIMIT is specified and is
	       not negative, splits into no more than that many fields (though
	       it may split into fewer).  If LIMIT is unspecified, trailing
	       null fields are stripped (which potential users of pop() would
	       do well to remember).  If LIMIT is negative, it is treated as
	       if an arbitrarily large LIMIT had been specified.

	       A pattern matching the null string (not to be confused with a
	       null pattern //, which is just one member of the set of
	       patterns matching a null string) will split the value of EXPR
	       into separate characters at each point it matches that way.
	       For example:

		   print join(':', split(/ */, 'hi there'));

	       produces the output 'h:i:t:h:e:r:e'.

	       The LIMIT parameter can be used to partially split a line

		   ($login, $passwd, $remainder) = split(/:/, $_, 3);

	       When assigning to a list, if LIMIT is omitted, Perl supplies a
	       LIMIT one larger than the number of variables in the list, to
	       avoid unnecessary work.	For the list above LIMIT would have
	       been 4 by default.  In time critical applications it behooves
	       you not to split into more fields than you really need.

	       If the PATTERN contains parentheses, additional array elements
	       are created from each matching substring in the delimiter.

		   split(/([,-])/, "1-10,20");

	       produces the list value

		   (1, '-', 10, ',', 20)

	       The pattern /PATTERN/ may be replaced with an expression to
	       specify patterns that vary at runtime.  (To do runtime
	       compilation only once, use /$variable/o.)

	       As a special case, specifying a PATTERN of space (' ') will
	       split on white space just as split with no arguments does.
	       Thus, split(' ') can be used to emulate awk's default behavior,
	       whereas split(/ /) will give you as many null initial fields as
	       there are leading spaces.  A split on /\s+/ is like a split('
	       ') except that any leading whitespace produces a null first
	       field.  A split with no arguments really does a split(' ', $_)
	       internally.

	       Example:

		   open(passwd, '/etc/passwd');
		   while (<passwd>) {
		       ($login, $passwd, $uid, $gid, $gcos,
			   $home, $shell) = split(/:/);
		       ...
		   }

	       (Note that $shell above will still have a newline on it.	 See
	       the chop, chomp,	 and join entries elsewhere in this document.)

       sprintf FORMAT,LIST
	       Returns a string formatted by the usual printf conventions of
	       the C language.	(The * character for an indirectly specified
	       length is not supported, but you can get the same effect by
	       interpolating a variable into the pattern.)

       sqrt EXPR
	       Return the square root of EXPR.	If EXPR is omitted, returns
	       square root of $_.

       srand EXPR
	       Sets the random number seed for the rand operator.  If EXPR is
	       omitted, does srand(time).  Of course, you'd need something
	       much more random than that for cryptographic purposes, since
	       it's easy to guess the current time.  Checksumming the
	       compressed output of rapidly changing operating system status
	       programs is the usual method.  Examples are posted regularly to
	       comp.security.unix.

       stat FILEHANDLE

       stat EXPR
	       Returns a 13-element array giving the status info for a file,
	       either the file opened via FILEHANDLE, or named by EXPR.
	       Returns a null list if the stat fails.  Typically used as
	       follows:

		   ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
		      $atime,$mtime,$ctime,$blksize,$blocks)
			  = stat($filename);

	       If stat is passed the special filehandle consisting of an
	       underline, no stat is done, but the current contents of the
	       stat structure from the last stat or filetest are returned.
	       Example:

		   if (-x $file && (($d) = stat(_)) && $d < 0) {
		       print "$file is executable NFS file\n";
		   }

	       (This only works on machines for which the device number is
	       negative under NFS.)

       study SCALAR

       study   Takes extra time to study SCALAR ($_ if unspecified) in
	       anticipation of doing many pattern matches on the string before
	       it is next modified.  This may or may not save time, depending
	       on the nature and number of patterns you are searching on, and
	       on the distribution of character frequencies in the string to
	       be searched--you probably want to compare runtimes with and
	       without it to see which runs faster.  Those loops which scan
	       for many short constant strings (including the constant parts
	       of more complex patterns) will benefit most.  You may have only
	       one study active at a time--if you study a different scalar the
	       first is "unstudied".  (The way study works is this: a linked
	       list of every character in the string to be searched is made,
	       so we know, for example, where all the 'k' characters are.
	       From each search string, the rarest character is selected,
	       based on some static frequency tables constructed from some C
	       programs and English text.  Only those places that contain this
	       "rarest" character are examined.)

	       For example, here is a loop which inserts index producing
	       entries before any line containing a certain pattern:

		   while (<>) {
		       study;
		       print ".IX foo\n" if /\bfoo\b/;
		       print ".IX bar\n" if /\bbar\b/;
		       print ".IX blurfl\n" if /\bblurfl\b/;
		       ...
		       print;
		   }

	       In searching for /\bfoo\b/, only those locations in $_ that
	       contain "f" will be looked at, because "f" is rarer than "o".
	       In general, this is a big win except in pathological cases.
	       The only question is whether it saves you more time than it
	       took to build the linked list in the first place.

	       Note that if you have to look for strings that you don't know
	       till runtime, you can build an entire loop as a string and eval
	       that to avoid recompiling all your patterns all the time.
	       Together with undefining $/ to input entire files as one
	       record, this can be very fast, often faster than specialized
	       programs like fgrep(1).	The following scans a list of files
	       (@files) for a list of words (@words), and prints out the names
	       of those files that contain a match:

		   $search = 'while (<>) { study;';
		   foreach $word (@words) {
		       $search .= "++\$seen{\$ARGV} if /\\b$word\\b/;\n";
		   }
		   $search .= "}";
		   @ARGV = @files;
		   undef $/;
		   eval $search;	       # this screams
		   $/ = "\n";	       # put back to normal input delim
		   foreach $file (sort keys(%seen)) {
		       print $file, "\n";
		   }

       substr EXPR,OFFSET,LEN

       substr EXPR,OFFSET
	       Extracts a substring out of EXPR and returns it.	 First
	       character is at offset 0, or whatever you've set $[ to.	If
	       OFFSET is negative, starts that far from the end of the string.
	       If LEN is omitted, returns everything to the end of the string.
	       If LEN is negative, leaves that many characters off the end of
	       the string.

	       You can use the substr() function as an lvalue, in which case
	       EXPR must be an lvalue.	If you assign something shorter than
	       LEN, the string will shrink, and if you assign something longer
	       than LEN, the string will grow to accommodate it.  To keep the
	       string the same length you may need to pad or chop your value
	       using sprintf().

       symlink OLDFILE,NEWFILE
	       Creates a new filename symbolically linked to the old filename.
	       Returns 1 for success, 0 otherwise.  On systems that don't
	       support symbolic links, produces a fatal error at run time.  To
	       check for that, use eval:

		   $symlink_exists = (eval 'symlink("","");', $@ eq '');

       syscall LIST
	       Calls the system call specified as the first element of the
	       list, passing the remaining elements as arguments to the system
	       call.  If unimplemented, produces a fatal error.	 The arguments
	       are interpreted as follows: if a given argument is numeric, the
	       argument is passed as an int.  If not, the pointer to the
	       string value is passed.	You are responsible to make sure a
	       string is pre-extended long enough to receive any result that
	       might be written into a string.	If your integer arguments are
	       not literals and have never been interpreted in a numeric
	       context, you may need to add 0 to them to force them to look
	       like numbers.

		   require 'syscall.ph';	       # may need to run h2ph
		   syscall(&SYS_write, fileno(STDOUT), "hi there\n", 9);

	       Note that Perl only supports passing of up to 14 arguments to
	       your system call, which in practice should usually suffice.

       sysread FILEHANDLE,SCALAR,LENGTH,OFFSET

       sysread FILEHANDLE,SCALAR,LENGTH
	       Attempts to read LENGTH bytes of data into variable SCALAR from
	       the specified FILEHANDLE, using the system call read(2).	 It
	       bypasses stdio, so mixing this with other kinds of reads may
	       cause confusion.	 Returns the number of bytes actually read, or
	       undef if there was an error.  SCALAR will be grown or shrunk to
	       the length actually read.  An OFFSET may be specified to place
	       the read data at some other place than the beginning of the
	       string.

       system LIST
	       Does exactly the same thing as "exec LIST" except that a fork
	       is done first, and the parent process waits for the child
	       process to complete.  Note that argument processing varies
	       depending on the number of arguments.  The return value is the
	       exit status of the program as returned by the wait() call.  To
	       get the actual exit value divide by 256.	 See also the exec
	       entry elsewhere in this document.

       syswrite FILEHANDLE,SCALAR,LENGTH,OFFSET

       syswrite FILEHANDLE,SCALAR,LENGTH
	       Attempts to write LENGTH bytes of data from variable SCALAR to
	       the specified FILEHANDLE, using the system call write(2).  It
	       bypasses stdio, so mixing this with prints may cause confusion.
	       Returns the number of bytes actually written, or undef if there
	       was an error.  An OFFSET may be specified to place the read
	       data at some other place than the beginning of the string.

       tell FILEHANDLE

       tell    Returns the current file position for FILEHANDLE.  FILEHANDLE
	       may be an expression whose value gives the name of the actual
	       filehandle.  If FILEHANDLE is omitted, assumes the file last
	       read.

       telldir DIRHANDLE
	       Returns the current position of the readdir() routines on
	       DIRHANDLE.  Value may be given to seekdir() to access a
	       particular location in a directory.  Has the same caveats about
	       possible directory compaction as the corresponding system
	       library routine.

       tie VARIABLE,PACKAGENAME,LIST
	       This function binds a variable to a package that will provide
	       the implementation for the variable.  VARIABLE is the name of
	       the variable to be enchanted.  PACKAGENAME is the name of a
	       package implementing objects of correct type.  Any additional
	       arguments are passed to the "new" method of the package
	       (meaning TIESCALAR, TIEARRAY, or TIEHASH).  Typically these are
	       arguments such as might be passed to the dbm_open() function of
	       C.

	       Note that functions such as keys() and values() may return huge
	       array values when used on large objects, like DBM files.	 You
	       may prefer to use the each() function to iterate over such.
	       Example:

		   # print out history file offsets
		   tie(%HIST, NDBM_File, '/usr/lib/news/history', 1, 0);
		   while (($key,$val) = each %HIST) {
		       print $key, ' = ', unpack('L',$val), "\n";
		   }
		   untie(%HIST);

	       A package implementing an associative array should have the
	       following methods:

		   TIEHASH objectname, LIST
		   DESTROY this
		   FETCH this, key
		   STORE this, key, value
		   DELETE this, key
		   EXISTS this, key
		   FIRSTKEY this
		   NEXTKEY this, lastkey

	       A package implementing an ordinary array should have the
	       following methods:

		   TIEARRAY objectname, LIST
		   DESTROY this
		   FETCH this, key
		   STORE this, key, value
		   [others TBD]

	       A package implementing a scalar should have the following
	       methods:

		   TIESCALAR objectname, LIST
		   DESTROY this
		   FETCH this,
		   STORE this, value

       time    Returns the number of non-leap seconds since 00:00:00 UTC,
	       January 1, 1970.	 Suitable for feeding to gmtime() and
	       localtime().

       times   Returns a four-element array giving the user and system times,
	       in seconds, for this process and the children of this process.

		   ($user,$system,$cuser,$csystem) = times;

       tr///   The translation operator.  See the perlop manpage.

       truncate FILEHANDLE,LENGTH

       truncate EXPR,LENGTH
	       Truncates the file opened on FILEHANDLE, or named by EXPR, to
	       the specified length.  Produces a fatal error if truncate isn't
	       implemented on your system.

       uc EXPR Returns an uppercased version of EXPR.  This is the internal
	       function implementing the \U escape in double-quoted strings.

       ucfirst EXPR
	       Returns the value of EXPR with the first character uppercased.
	       This is the internal function implementing the \u escape in
	       double-quoted strings.

       umask EXPR

       umask   Sets the umask for the process and returns the old one.	If
	       EXPR is omitted, merely returns current umask.

       undef EXPR

       undef   Undefines the value of EXPR, which must be an lvalue.  Use only
	       on a scalar value, an entire array, or a subroutine name (using
	       "&").  (Using undef() will probably not do what you expect on
	       most predefined variables or DBM list values, so don't do
	       that.)  Always returns the undefined value.  You can omit the
	       EXPR, in which case nothing is undefined, but you still get an
	       undefined value that you could, for instance, return from a
	       subroutine.  Examples:

		   undef $foo;
		   undef $bar{'blurfl'};
		   undef @ary;
		   undef %assoc;
		   undef &mysub;
		   return (wantarray ? () : undef) if $they_blew_it;

       unlink LIST
	       Deletes a list of files.	 Returns the number of files
	       successfully deleted.

		   $cnt = unlink 'a', 'b', 'c';
		   unlink @goners;
		   unlink <*.bak>;

	       Note: unlink will not delete directories unless you are
	       superuser and the -U flag is supplied to Perl.  Even if these
	       conditions are met, be warned that unlinking a directory can
	       inflict damage on your filesystem.  Use rmdir instead.

       unpack TEMPLATE,EXPR
	       Unpack does the reverse of pack: it takes a string representing
	       a structure and expands it out into a list value, returning the
	       array value.  (In a scalar context, it merely returns the first
	       value produced.)	 The TEMPLATE has the same format as in the
	       pack function.  Here's a subroutine that does substring:

		   sub substr {
		       local($what,$where,$howmuch) = @_;
		       unpack("x$where a$howmuch", $what);
		   }

	       and then there's

		   sub ordinal { unpack("c",$_[0]); } # same as ord()

	       In addition, you may prefix a field with a %<number> to
	       indicate that you want a <number>-bit checksum of the items
	       instead of the items themselves.	 Default is a 16-bit checksum.
	       For example, the following computes the same number as the
	       System V sum program:

		   while (<>) {
		       $checksum += unpack("%16C*", $_);
		   }
		   $checksum %= 65536;

	       The following efficiently counts the number of set bits in a
	       bit vector:

		   $setbits = unpack("%32b*", $selectmask);

       untie VARIABLE
	       Breaks the binding between a variable and a package.  (See
	       tie().)

       unshift ARRAY,LIST
	       Does the opposite of a shift.  Or the opposite of a push,
	       depending on how you look at it.	 Prepends list to the front of
	       the array, and returns the new number of elements in the array.

		   unshift(ARGV, '-e') unless $ARGV[0] =~ /^-/;

	       Note the LIST is prepended whole, not one element at a time, so
	       the prepended elements stay in the same order.  Use reverse to
	       do the reverse.

       use Module LIST

       use Module
	       Imports some semantics into the current package from the named
	       module, generally by aliasing certain subroutine or variable
	       names into your package.	 It is exactly equivalent to

		   BEGIN { require Module; import Module LIST; }

	       If you don't want your namespace altered, use require instead.

	       The BEGIN forces the require and import to happen at compile
	       time.  The require makes sure the module is loaded into memory
	       if it hasn't been yet.  The import is not a builtin--it's just
	       an ordinary static method call into the "Module" package to
	       tell the module to import the list of features back into the
	       current package.	 The module can implement its import method
	       any way it likes, though most modules just choose to derive
	       their import method via inheritance from the Exporter class
	       that is defined in the Exporter module.

	       Because this is a wide-open interface, pragmas (compiler
	       directives) are also implemented this way.  Currently
	       implemented pragmas are:

		   use integer;
		   use sigtrap qw(SEGV BUS);
		   use strict  qw(subs vars refs);
		   use subs    qw(afunc blurfl);

	       These pseudomodules import semantics into the current block
	       scope, unlike ordinary modules, which import symbols into the
	       current package (which are effective through the end of the
	       file).

	       There's a corresponding "no" command that unimports meanings
	       imported by use.

		   no integer;
		   no strict 'refs';

	       See the perlmod manpage for a list of standard modules and
	       pragmas.

       utime LIST
	       Changes the access and modification times on each file of a
	       list of files.  The first two elements of the list must be the
	       NUMERICAL access and modification times, in that order.
	       Returns the number of files successfully changed.  The inode
	       modification time of each file is set to the current time.
	       Example of a "touch" command:

		   #!/usr/bin/perl
		   $now = time;
		   utime $now, $now, @ARGV;

       values ASSOC_ARRAY
	       Returns a normal array consisting of all the values of the
	       named associative array.	 (In a scalar context, returns the
	       number of values.)  The values are returned in an apparently
	       random order, but it is the same order as either the keys() or
	       each() function would produce on the same array.	 See also
	       keys() and each().

       vec EXPR,OFFSET,BITS
	       Treats a string as a vector of unsigned integers, and returns
	       the value of the bitfield specified.  May also be assigned to.
	       BITS must be a power of two from 1 to 32.

	       Vectors created with vec() can also be manipulated with the
	       logical operators ⎪, & and ^, which will assume a bit vector
	       operation is desired when both operands are strings.

	       To transform a bit vector into a string or array of 0's and
	       1's, use these:

		   $bits = unpack("b*", $vector);
		   @bits = split(//, unpack("b*", $vector));

	       If you know the exact length in bits, it can be used in place
	       of the *.

       wait    Waits for a child process to terminate and returns the pid of
	       the deceased process, or -1 if there are no child processes.
	       The status is returned in $?.

       waitpid PID,FLAGS
	       Waits for a particular child process to terminate and returns
	       the pid of the deceased process, or -1 if there is no such
	       child process.  The status is returned in $?.  If you say

		   use POSIX "wait_h";
		   ...
		   waitpid(-1,&WNOHANG);

	       then you can do a non-blocking wait for any process.  Non-
	       blocking wait is only available on machines supporting either
	       the waitpid(2) or wait4(2) system calls.	 However, waiting for
	       a particular pid with FLAGS of 0 is implemented everywhere.
	       (Perl emulates the system call by remembering the status values
	       of processes that have exited but have not been harvested by
	       the Perl script yet.)

       wantarray
	       Returns TRUE if the context of the currently executing
	       subroutine is looking for a list value.	Returns FALSE if the
	       context is looking for a scalar.

		   return wantarray ? () : undef;

       warn LIST
	       Produces a message on STDERR just like die(), but doesn't exit
	       or throw an exception.

       write FILEHANDLE

       write EXPR

       write   Writes a formatted record (possibly multi-line) to the
	       specified file, using the format associated with that file.  By
	       default the format for a file is the one having the same name
	       is the filehandle, but the format for the current output
	       channel (see the select() function) may be set explicitly by
	       assigning the name of the format to the $~ variable.

	       Top of form processing is handled automatically:	 if there is
	       insufficient room on the current page for the formatted record,
	       the page is advanced by writing a form feed, a special top-of-
	       page format is used to format the new page header, and then the
	       record is written.  By default the top-of-page format is the
	       name of the filehandle with "_TOP" appended, but it may be
	       dynamically set to the format of your choice by assigning the
	       name to the $^ variable while the filehandle is selected.  The
	       number of lines remaining on the current page is in variable
	       $-, which can be set to 0 to force a new page.

	       If FILEHANDLE is unspecified, output goes to the current
	       default output channel, which starts out as STDOUT but may be
	       changed by the select operator.	If the FILEHANDLE is an EXPR,
	       then the expression is evaluated and the resulting string is
	       used to look up the name of the FILEHANDLE at run time.	For
	       more on formats, see the perlform manpage.

	       Note that write is NOT the opposite of read.  Unfortunately.

       y///    The translation operator.  See the section on tr/// in the
	       perlop manpage.

3rd Berkeley Distribution					   PERLFUNC(1)
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