FM / pod

/usr/share/perl5/pod

Name	Size	Mode	Actions
perl.pod	16270	0644	edit dl rm
perl56delta.pod	107201	0644	edit dl rm
perl58delta.pod	115165	0644	edit dl rm
perl561delta.pod	124713	0644	edit dl rm
perl581delta.pod	38061	0644	edit dl rm
perl582delta.pod	4470	0644	edit dl rm
perl583delta.pod	6335	0644	edit dl rm
perl584delta.pod	7363	0644	edit dl rm
perl585delta.pod	5889	0644	edit dl rm
perl586delta.pod	4651	0644	edit dl rm
perl587delta.pod	8357	0644	edit dl rm
perl588delta.pod	25272	0644	edit dl rm
perl589delta.pod	53900	0644	edit dl rm
perl5004delta.pod	56240	0644	edit dl rm
perl5005delta.pod	34283	0644	edit dl rm
perl5100delta.pod	55535	0644	edit dl rm
perl5101delta.pod	43888	0644	edit dl rm
perl5120delta.pod	89272	0644	edit dl rm
perl5121delta.pod	10141	0644	edit dl rm
perl5122delta.pod	9603	0644	edit dl rm
perl5123delta.pod	4100	0644	edit dl rm
perl5124delta.pod	3672	0644	edit dl rm
perl5125delta.pod	7683	0644	edit dl rm
perl5140delta.pod	144324	0644	edit dl rm
perl5141delta.pod	7966	0644	edit dl rm
perl5142delta.pod	6892	0644	edit dl rm
perl5143delta.pod	7760	0644	edit dl rm
perl5144delta.pod	6327	0644	edit dl rm
perl5160delta.pod	133651	0644	edit dl rm
perl5161delta.pod	6142	0644	edit dl rm
perl5162delta.pod	3594	0644	edit dl rm
perl5163delta.pod	4085	0644	edit dl rm
perl5180delta.pod	119431	0644	edit dl rm
perl5181delta.pod	6595	0644	edit dl rm
perl5182delta.pod	5335	0644	edit dl rm
perl5184delta.pod	4642	0644	edit dl rm
perl5200delta.pod	115699	0644	edit dl rm
perl5201delta.pod	10899	0644	edit dl rm
perl5202delta.pod	12509	0644	edit dl rm
perl5203delta.pod	9392	0644	edit dl rm
perl5220delta.pod	130963	0644	edit dl rm
perl5221delta.pod	10767	0644	edit dl rm
perl5222delta.pod	12629	0644	edit dl rm
perl5223delta.pod	8456	0644	edit dl rm
perl5224delta.pod	4460	0644	edit dl rm
perl5240delta.pod	64927	0644	edit dl rm
perl5241delta.pod	8215	0644	edit dl rm
perl5242delta.pod	4113	0644	edit dl rm
perl5243delta.pod	11428	0644	edit dl rm
perl5244delta.pod	4510	0644	edit dl rm
perl5260delta.pod	101836	0644	edit dl rm
perl5261delta.pod	7927	0644	edit dl rm
perl5262delta.pod	7880	0644	edit dl rm
perl5263delta.pod	7063	0644	edit dl rm
perl5280delta.pod	72113	0644	edit dl rm
perlaix.pod	20437	0644	edit dl rm
perlamiga.pod	5749	0644	edit dl rm
perlandroid.pod	7871	0644	edit dl rm
perlapi.pod	443535	0644	edit dl rm
perlapio.pod	19285	0644	edit dl rm
perlartistic.pod	7010	0644	edit dl rm
perlbook.pod	8338	0644	edit dl rm
perlboot.pod	294	0644	edit dl rm
perlbot.pod	304	0644	edit dl rm
perlbs2000.pod	8058	0644	edit dl rm
perlcall.pod	56706	0644	edit dl rm
perlce.pod	14602	0644	edit dl rm
perlcheat.pod	4481	0644	edit dl rm
perlclib.pod	9619	0644	edit dl rm
perlcn.pod	4691	0644	edit dl rm
perlcommunity.pod	7217	0644	edit dl rm
perlcygwin.pod	27199	0644	edit dl rm
perldata.pod	46743	0644	edit dl rm
perldbmfilter.pod	4981	0644	edit dl rm
perldebguts.pod	38535	0644	edit dl rm
perldebtut.pod	22152	0644	edit dl rm
perldebug.pod	39258	0644	edit dl rm
perldelta.pod	7063	0644	edit dl rm
perldeprecation.pod	18169	0644	edit dl rm
perldiag.pod	284572	0644	edit dl rm
perldos.pod	10522	0644	edit dl rm
perldsc.pod	25614	0644	edit dl rm
perldtrace.pod	7958	0644	edit dl rm
perlebcdic.pod	84233	0644	edit dl rm
perlembed.pod	37196	0644	edit dl rm
perlexperiment.pod	7195	0644	edit dl rm
perlfork.pod	13355	0644	edit dl rm
perlform.pod	16608	0644	edit dl rm
perlfreebsd.pod	1610	0644	edit dl rm
perlfunc.pod	392957	0644	edit dl rm
perlgit.pod	33509	0644	edit dl rm
perlgpl.pod	13815	0644	edit dl rm
perlguts.pod	139329	0644	edit dl rm
perlhack.pod	40445	0644	edit dl rm
perlhacktips.pod	55509	0644	edit dl rm
perlhacktut.pod	6153	0644	edit dl rm
perlhaiku.pod	1508	0644	edit dl rm
perlhist.pod	53546	0644	edit dl rm
perlhpux.pod	30509	0644	edit dl rm
perlhurd.pod	1993	0644	edit dl rm
perlintern.pod	54572	0644	edit dl rm
perlinterp.pod	33687	0644	edit dl rm
perlintro.pod	22119	0644	edit dl rm
perliol.pod	34185	0644	edit dl rm
perlipc.pod	70829	0644	edit dl rm
perlirix.pod	4395	0644	edit dl rm
perljp.pod	7521	0644	edit dl rm
perlko.pod	12259	0644	edit dl rm
perllexwarn.pod	355	0644	edit dl rm
perllinux.pod	1488	0644	edit dl rm
perllocale.pod	68678	0644	edit dl rm
perllol.pod	9580	0644	edit dl rm
perlmacos.pod	1001	0644	edit dl rm
perlmacosx.pod	12060	0644	edit dl rm
perlmod.pod	26250	0644	edit dl rm
perlmodinstall.pod	12792	0644	edit dl rm
perlmodlib.pod	76482	0644	edit dl rm
perlmodstyle.pod	22575	0644	edit dl rm
perlmroapi.pod	3212	0644	edit dl rm
perlnetware.pod	6648	0644	edit dl rm
perlnewmod.pod	11036	0644	edit dl rm
perlnumber.pod	8353	0644	edit dl rm
perlobj.pod	35537	0644	edit dl rm
perlootut.pod	26783	0644	edit dl rm
perlop.pod	136252	0644	edit dl rm
perlopenbsd.pod	1204	0644	edit dl rm
perlopentut.pod	9455	0644	edit dl rm
perlos2.pod	93351	0644	edit dl rm
perlos390.pod	15674	0644	edit dl rm
perlos400.pod	4768	0644	edit dl rm
perlpacktut.pod	51282	0644	edit dl rm
perlperf.pod	49881	0644	edit dl rm
perlplan9.pod	5125	0644	edit dl rm
perlpod.pod	22196	0644	edit dl rm
perlpodspec.pod	68476	0644	edit dl rm
perlpolicy.pod	25629	0644	edit dl rm
perlport.pod	87602	0644	edit dl rm
perlpragma.pod	5176	0644	edit dl rm
perlqnx.pod	6673	0644	edit dl rm
perlre.pod	120901	0644	edit dl rm
perlreapi.pod	30334	0644	edit dl rm
perlrebackslash.pod	31817	0644	edit dl rm
perlrecharclass.pod	49029	0644	edit dl rm
perlref.pod	35304	0644	edit dl rm
perlreftut.pod	18790	0644	edit dl rm
perlreguts.pod	38328	0644	edit dl rm
perlrepository.pod	509	0644	edit dl rm
perlrequick.pod	18497	0644	edit dl rm
perlreref.pod	14744	0644	edit dl rm
perlretut.pod	121257	0644	edit dl rm
perlriscos.pod	1529	0644	edit dl rm
perlrun.pod	53550	0644	edit dl rm
perlsec.pod	26184	0644	edit dl rm
perlsolaris.pod	29822	0644	edit dl rm
perlsource.pod	6876	0644	edit dl rm
perlstyle.pod	8630	0644	edit dl rm
perlsub.pod	72967	0644	edit dl rm
perlsymbian.pod	15359	0644	edit dl rm
perlsyn.pod	44512	0644	edit dl rm
perlsynology.pod	7778	0644	edit dl rm
perlthrtut.pod	46459	0644	edit dl rm
perltie.pod	38607	0644	edit dl rm
perltoc.pod	694171	0644	edit dl rm
perltodo.pod	376	0644	edit dl rm
perltooc.pod	294	0644	edit dl rm
perltoot.pod	294	0644	edit dl rm
perltrap.pod	10620	0644	edit dl rm
perltru64.pod	8492	0644	edit dl rm
perltw.pod	4477	0644	edit dl rm
perlunicode.pod	82491	0644	edit dl rm
perlunicook.pod	25488	0644	edit dl rm
perlunifaq.pod	13647	0644	edit dl rm
perluniintro.pod	38340	0644	edit dl rm
perluniprops.pod	285306	0644	edit dl rm
perlunitut.pod	7951	0644	edit dl rm
perlutil.pod	7640	0644	edit dl rm
perlvar.pod	78364	0644	edit dl rm
perlvms.pod	50823	0644	edit dl rm
perlvos.pod	3843	0644	edit dl rm
perlwin32.pod	39298	0644	edit dl rm
perlxs.pod	78920	0644	edit dl rm
perlxstut.pod	50095	0644	edit dl rm
perlxstypemap.pod	24001	0644	edit dl rm

Edit: /usr/share/perl5/pod/perlform.pod (16608B)

=head1 NAME
X<format> X<report> X<chart>

perlform - Perl formats

=head1 DESCRIPTION

Perl has a mechanism to help you generate simple reports and charts.  To
facilitate this, Perl helps you code up your output page close to how it
will look when it's printed.  It can keep track of things like how many
lines are on a page, what page you're on, when to print page headers,
etc.  Keywords are borrowed from FORTRAN: format() to declare and write()
to execute; see their entries in L<perlfunc>.  Fortunately, the layout is
much more legible, more like BASIC's PRINT USING statement.  Think of it
as a poor man's nroff(1).
X<nroff>

Formats, like packages and subroutines, are declared rather than
executed, so they may occur at any point in your program.  (Usually it's
best to keep them all together though.) They have their own namespace
apart from all the other "types" in Perl.  This means that if you have a
function named "Foo", it is not the same thing as having a format named
"Foo".  However, the default name for the format associated with a given
filehandle is the same as the name of the filehandle.  Thus, the default
format for STDOUT is named "STDOUT", and the default format for filehandle
TEMP is named "TEMP".  They just look the same.  They aren't.

Output record formats are declared as follows:

format NAME =
    FORMLIST
    .

If the name is omitted, format "STDOUT" is defined. A single "." in 
column 1 is used to terminate a format.  FORMLIST consists of a sequence 
of lines, each of which may be one of three types:

=over 4

=item 1.

A comment, indicated by putting a '#' in the first column.

=item 2.

A "picture" line giving the format for one output line.

=item 3.

An argument line supplying values to plug into the previous picture line.

=back

Picture lines contain output field definitions, intermingled with
literal text. These lines do not undergo any kind of variable interpolation.
Field definitions are made up from a set of characters, for starting and
extending a field to its desired width. This is the complete set of
characters for field definitions:
X<format, picture line>
X<@> X<^> X<< < >> X<< | >> X<< > >> X<#> X<0> X<.> X<...>
X<@*> X<^*> X<~> X<~~>

@    start of regular field
   ^    start of special field
   <    pad character for left justification
   |    pad character for centering
   >    pad character for right justification
   #    pad character for a right-justified numeric field
   0    instead of first #: pad number with leading zeroes
   .    decimal point within a numeric field
   ...  terminate a text field, show "..." as truncation evidence
   @*   variable width field for a multi-line value
   ^*   variable width field for next line of a multi-line value
   ~    suppress line with all fields empty
   ~~   repeat line until all fields are exhausted

Each field in a picture line starts with either "@" (at) or "^" (caret),
indicating what we'll call, respectively, a "regular" or "special" field.
The choice of pad characters determines whether a field is textual or
numeric. The tilde operators are not part of a field.  Let's look at
the various possibilities in detail.

=head2 Text Fields
X<format, text field>

The length of the field is supplied by padding out the field with multiple 
"E<lt>", "E<gt>", or "|" characters to specify a non-numeric field with,
respectively, left justification, right justification, or centering. 
For a regular field, the value (up to the first newline) is taken and
printed according to the selected justification, truncating excess characters.
If you terminate a text field with "...", three dots will be shown if
the value is truncated. A special text field may be used to do rudimentary 
multi-line text block filling; see L</Using Fill Mode> for details.

Example:
      format STDOUT =
      @<<<<<<   @||||||   @>>>>>>
      "left",   "middle", "right"
      .
   Output:
      left      middle    right

=head2 Numeric Fields
X<#> X<format, numeric field>

Using "#" as a padding character specifies a numeric field, with
right justification. An optional "." defines the position of the
decimal point. With a "0" (zero) instead of the first "#", the
formatted number will be padded with leading zeroes if necessary.
A special numeric field is blanked out if the value is undefined.
If the resulting value would exceed the width specified the field is
filled with "#" as overflow evidence.

Example:
      format STDOUT =
      @###   @.###   @##.###  @###   @###   ^####
       42,   3.1415,  undef,    0, 10000,   undef
      .
   Output:
        42   3.142     0.000     0   ####

=head2 The Field @* for Variable-Width Multi-Line Text
X<@*>

The field "@*" can be used for printing multi-line, nontruncated
values; it should (but need not) appear by itself on a line. A final
line feed is chomped off, but all other characters are emitted verbatim.

=head2 The Field ^* for Variable-Width One-line-at-a-time Text
X<^*>

Like "@*", this is a variable-width field. The value supplied must be a 
scalar variable. Perl puts the first line (up to the first "\n") of the 
text into the field, and then chops off the front of the string so that 
the next time the variable is referenced, more of the text can be printed. 
The variable will I<not> be restored.

Example:
      $text = "line 1\nline 2\nline 3";
      format STDOUT =
      Text: ^*
            $text
      ~~    ^*
            $text
      .
   Output:
      Text: line 1
            line 2
            line 3

=head2 Specifying Values
X<format, specifying values>

The values are specified on the following format line in the same order as
the picture fields.  The expressions providing the values must be
separated by commas.  They are all evaluated in a list context
before the line is processed, so a single list expression could produce
multiple list elements.  The expressions may be spread out to more than
one line if enclosed in braces.  If so, the opening brace must be the first
token on the first line.  If an expression evaluates to a number with a
decimal part, and if the corresponding picture specifies that the decimal
part should appear in the output (that is, any picture except multiple "#"
characters B<without> an embedded "."), the character used for the decimal
point is determined by the current LC_NUMERIC locale if C<use locale> is in
effect.  This means that, if, for example, the run-time environment happens
to specify a German locale, "," will be used instead of the default ".".  See
L<perllocale> and L</"WARNINGS"> for more information.

=head2 Using Fill Mode
X<format, fill mode>

On text fields the caret enables a kind of fill mode.  Instead of an
arbitrary expression, the value supplied must be a scalar variable
that contains a text string.  Perl puts the next portion of the text into
the field, and then chops off the front of the string so that the next time
the variable is referenced, more of the text can be printed.  (Yes, this
means that the variable itself is altered during execution of the write()
call, and is not restored.)  The next portion of text is determined by
a crude line-breaking algorithm. You may use the carriage return character
(C<\r>) to force a line break. You can change which characters are legal 
to break on by changing the variable C<$:> (that's 
$FORMAT_LINE_BREAK_CHARACTERS if you're using the English module) to a 
list of the desired characters.

Normally you would use a sequence of fields in a vertical stack associated 
with the same scalar variable to print out a block of text. You might wish 
to end the final field with the text "...", which will appear in the output 
if the text was too long to appear in its entirety.

=head2 Suppressing Lines Where All Fields Are Void
X<format, suppressing lines>

Using caret fields can produce lines where all fields are blank. You can
suppress such lines by putting a "~" (tilde) character anywhere in the
line.  The tilde will be translated to a space upon output.

=head2 Repeating Format Lines
X<format, repeating lines>

If you put two contiguous tilde characters "~~" anywhere into a line,
the line will be repeated until all the fields on the line are exhausted,
i.e. undefined. For special (caret) text fields this will occur sooner or
later, but if you use a text field of the at variety, the  expression you
supply had better not give the same value every time forever! (C<shift(@f)>
is a simple example that would work.)  Don't use a regular (at) numeric 
field in such lines, because it will never go blank.

=head2 Top of Form Processing
X<format, top of form> X<top> X<header>

Top-of-form processing is by default handled by a format with the
same name as the current filehandle with "_TOP" concatenated to it.
It's triggered at the top of each page.  See L<perlfunc/write>.

Examples:

# a report on the /etc/passwd file
 format STDOUT_TOP =
                         Passwd File
 Name                Login    Office   Uid   Gid Home
 ------------------------------------------------------------------
 .
 format STDOUT =
 @<<<<<<<<<<<<<<<<<< @||||||| @<<<<<<@>>>> @>>>> @<<<<<<<<<<<<<<<<<
 $name,              $login,  $office,$uid,$gid, $home
 .

# a report from a bug report form
 format STDOUT_TOP =
                         Bug Reports
 @<<<<<<<<<<<<<<<<<<<<<<<     @|||         @>>>>>>>>>>>>>>>>>>>>>>>
 $system,                      $%,         $date
 ------------------------------------------------------------------
 .
 format STDOUT =
 Subject: @<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
          $subject
 Index: @<<<<<<<<<<<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<
        $index,                       $description
 Priority: @<<<<<<<<<< Date: @<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<
           $priority,        $date,   $description
 From: @<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<
       $from,                         $description
 Assigned to: @<<<<<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<
              $programmer,            $description
 ~                                    ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<
                                      $description
 ~                                    ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<
                                      $description
 ~                                    ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<
                                      $description
 ~                                    ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<
                                      $description
 ~                                    ^<<<<<<<<<<<<<<<<<<<<<<<...
                                      $description
 .

It is possible to intermix print()s with write()s on the same output
channel, but you'll have to handle C<$-> (C<$FORMAT_LINES_LEFT>)
yourself.

=head2 Format Variables
X<format variables>
X<format, variables>

The current format name is stored in the variable C<$~> (C<$FORMAT_NAME>),
and the current top of form format name is in C<$^> (C<$FORMAT_TOP_NAME>).
The current output page number is stored in C<$%> (C<$FORMAT_PAGE_NUMBER>),
and the number of lines on the page is in C<$=> (C<$FORMAT_LINES_PER_PAGE>).
Whether to autoflush output on this handle is stored in C<$|>
(C<$OUTPUT_AUTOFLUSH>).  The string output before each top of page (except
the first) is stored in C<$^L> (C<$FORMAT_FORMFEED>).  These variables are
set on a per-filehandle basis, so you'll need to select() into a different
one to affect them:

select((select(OUTF),
	    $~ = "My_Other_Format",
	    $^ = "My_Top_Format"
	   )[0]);

Pretty ugly, eh?  It's a common idiom though, so don't be too surprised
when you see it.  You can at least use a temporary variable to hold
the previous filehandle: (this is a much better approach in general,
because not only does legibility improve, you now have an intermediary
stage in the expression to single-step the debugger through):

$ofh = select(OUTF);
    $~ = "My_Other_Format";
    $^ = "My_Top_Format";
    select($ofh);

If you use the English module, you can even read the variable names:

use English;
    $ofh = select(OUTF);
    $FORMAT_NAME     = "My_Other_Format";
    $FORMAT_TOP_NAME = "My_Top_Format";
    select($ofh);

But you still have those funny select()s.  So just use the FileHandle
module.  Now, you can access these special variables using lowercase
method names instead:

use FileHandle;
    format_name     OUTF "My_Other_Format";
    format_top_name OUTF "My_Top_Format";

Much better!

=head1 NOTES

Because the values line may contain arbitrary expressions (for at fields,
not caret fields), you can farm out more sophisticated processing
to other functions, like sprintf() or one of your own.  For example:

format Ident =
	@<<<<<<<<<<<<<<<
	&commify($n)
    .

To get a real at or caret into the field, do this:

format Ident =
    I have an @ here.
	    "@"
    .

To center a whole line of text, do something like this:

format Ident =
    @|||||||||||||||||||||||||||||||||||||||||||||||
	    "Some text line"
    .

There is no builtin way to say "float this to the right hand side
of the page, however wide it is."  You have to specify where it goes.
The truly desperate can generate their own format on the fly, based
on the current number of columns, and then eval() it:

$format  = "format STDOUT = \n"
             . '^' . '<' x $cols . "\n"
             . '$entry' . "\n"
             . "\t^" . "<" x ($cols-8) . "~~\n"
             . '$entry' . "\n"
             . ".\n";
    print $format if $Debugging;
    eval $format;
    die $@ if $@;

Which would generate a format looking something like this:

format STDOUT =
 ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
 $entry
         ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<~~
 $entry
 .

Here's a little program that's somewhat like fmt(1):

format =
 ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ~~
 $_

$/ = '';
 while (<>) {
     s/\s*\n\s*/ /g;
     write;
 }

=head2 Footers
X<format, footer> X<footer>

While $FORMAT_TOP_NAME contains the name of the current header format,
there is no corresponding mechanism to automatically do the same thing
for a footer.  Not knowing how big a format is going to be until you
evaluate it is one of the major problems.  It's on the TODO list.

Here's one strategy:  If you have a fixed-size footer, you can get footers
by checking $FORMAT_LINES_LEFT before each write() and print the footer
yourself if necessary.

Here's another strategy: Open a pipe to yourself, using C<open(MYSELF, "|-")>
(see L<perlfunc/open>) and always write() to MYSELF instead of STDOUT.
Have your child process massage its STDIN to rearrange headers and footers
however you like.  Not very convenient, but doable.

=head2 Accessing Formatting Internals
X<format, internals>

For low-level access to the formatting mechanism, you may use formline()
and access C<$^A> (the $ACCUMULATOR variable) directly.

For example:

$str = formline <<'END', 1,2,3;
    @<<<  @|||  @>>>
    END

print "Wow, I just stored '$^A' in the accumulator!\n";

Or to make an swrite() subroutine, which is to write() what sprintf()
is to printf(), do this:

use Carp;
    sub swrite {
	croak "usage: swrite PICTURE ARGS" unless @_;
	my $format = shift;
	$^A = "";
	formline($format,@_);
	return $^A;
    }

$string = swrite(<<'END', 1, 2, 3);
 Check me out
 @<<<  @|||  @>>>
 END
    print $string;

=head1 WARNINGS

The lone dot that ends a format can also prematurely end a mail
message passing through a misconfigured Internet mailer (and based on
experience, such misconfiguration is the rule, not the exception).  So
when sending format code through mail, you should indent it so that
the format-ending dot is not on the left margin; this will prevent
SMTP cutoff.

Lexical variables (declared with "my") are not visible within a
format unless the format is declared within the scope of the lexical
variable.

If a program's environment specifies an LC_NUMERIC locale and C<use
locale> is in effect when the format is declared, the locale is used
to specify the decimal point character in formatted output.  Formatted
output cannot be controlled by C<use locale> at the time when write()
is called. See L<perllocale> for further discussion of locale handling.

Within strings that are to be displayed in a fixed-length text field,
each control character is substituted by a space. (But remember the
special meaning of C<\r> when using fill mode.) This is done to avoid
misalignment when control characters "disappear" on some output media.

cmd: