Term::ANSIColor(3pm) Perl Programmers Reference Guide Term::ANSIColor(3pm)
NAME
Term::ANSIColor - Color screen output using ANSI escape sequences
SYNOPSIS
use Term::ANSIColor;
print color 'bold blue';
print "This text is bold blue.\n";
print color 'reset';
print "This text is normal.\n";
print colored ("Yellow on magenta.\n", 'yellow on_magenta');
print "This text is normal.\n";
print colored ['yellow on_magenta'], "Yellow on magenta.\n";
use Term::ANSIColor qw(uncolor);
print uncolor '01;31', "\n";
use Term::ANSIColor qw(:constants);
print BOLD, BLUE, "This text is in bold blue.\n", RESET;
use Term::ANSIColor qw(:constants);
$Term::ANSIColor::AUTORESET = 1;
print BOLD BLUE "This text is in bold blue.\n";
print "This text is normal.\n";
DESCRIPTION
This module has two interfaces, one through color() and colored() and the other through constants.
It also offers the utility function uncolor(), which has to be explicitly imported to be used (see
SYNOPSIS).
color() takes any number of strings as arguments and considers them to be space-separated lists of
attributes. It then forms and returns the escape sequence to set those attributes. It doesn't print
it out, just returns it, so you'll have to print it yourself if you want to (this is so that you can
save it as a string, pass it to something else, send it to a file handle, or do anything else with it
that you might care to).
uncolor() performs the opposite translation, turning escape sequences into a list of strings.
The recognized attributes (all of which should be fairly intuitive) are clear, reset, dark, bold,
underline, underscore, blink, reverse, concealed, black, red, green, yellow, blue, magenta, on_black,
on_red, on_green, on_yellow, on_blue, on_magenta, on_cyan, and on_white. Case is not significant.
Underline and underscore are equivalent, as are clear and reset, so use whichever is the most intu-itive intuitive
itive to you. The color alone sets the foreground color, and on_color sets the background color.
Note that not all attributes are supported by all terminal types, and some terminals may not support
any of these sequences. Dark, blink, and concealed in particular are frequently not implemented.
Attributes, once set, last until they are unset (by sending the attribute "reset"). Be careful to do
this, or otherwise your attribute will last after your script is done running, and people get very
annoyed at having their prompt and typing changed to weird colors.
As an aid to help with this, colored() takes a scalar as the first argument and any number of
attribute strings as the second argument and returns the scalar wrapped in escape codes so that the
attributes will be set as requested before the string and reset to normal after the string. Alter-nately, Alternately,
nately, you can pass a reference to an array as the first argument, and then the contents of that
array will be taken as attributes and color codes and the remainder of the arguments as text to col-orize. colorize.
orize.
Normally, colored() just puts attribute codes at the beginning and end of the string, but if you set
$Term::ANSIColor::EACHLINE to some string, that string will be considered the line delimiter and the
attribute will be set at the beginning of each line of the passed string and reset at the end of each
line. This is often desirable if the output is being sent to a program like a pager that can be con-fused confused
fused by attributes that span lines. Normally you'll want to set $Term::ANSIColor::EACHLINE to "\n"
to use this feature.
Alternately, if you import ":constants", you can use the constants CLEAR, RESET, BOLD, DARK, UNDER-LINE, UNDERLINE,
LINE, UNDERSCORE, BLINK, REVERSE, CONCEALED, BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE,
ON_BLACK, ON_RED, ON_GREEN, ON_YELLOW, ON_BLUE, ON_MAGENTA, ON_CYAN, and ON_WHITE directly. These
are the same as color('attribute') and can be used if you prefer typing:
print BOLD BLUE ON_WHITE "Text\n", RESET;
to
print colored ("Text\n", 'bold blue on_white');
When using the constants, if you don't want to have to remember to add the ", RESET" at the end of
each print line, you can set $Term::ANSIColor::AUTORESET to a true value. Then, the display mode
will automatically be reset if there is no comma after the constant. In other words, with that vari-able variable
able set:
print BOLD BLUE "Text\n";
will reset the display mode afterwards, whereas:
print BOLD, BLUE, "Text\n";
will not.
The subroutine interface has the advantage over the constants interface in that only two subroutines
are exported into your namespace, versus twenty-two in the constants interface. On the flip side,
the constants interface has the advantage of better compile time error checking, since misspelled
names of colors or attributes in calls to color() and colored() won't be caught until runtime whereas
misspelled names of constants will be caught at compile time. So, polute your namespace with almost
two dozen subroutines that you may not even use that often, or risk a silly bug by mistyping an
attribute. Your choice, TMTOWTDI after all.
DIAGNOSTICS
Bad escape sequence %s
(F) You passed an invalid ANSI escape sequence to uncolor().
Bareword "%s" not allowed while "strict subs" in use
(F) You probably mistyped a constant color name such as:
$Foobar = FOOBAR . "This line should be blue\n";
or:
@Foobar = FOOBAR, "This line should be blue\n";
This will only show up under use strict (another good reason to run under use strict).
Invalid attribute name %s
(F) You passed an invalid attribute name to either color() or colored().
Name "%s" used only once: possible typo
(W) You probably mistyped a constant color name such as:
print FOOBAR "This text is color FOOBAR\n";
It's probably better to always use commas after constant names in order to force the next error.
No comma allowed after filehandle
(F) You probably mistyped a constant color name such as:
print FOOBAR, "This text is color FOOBAR\n";
Generating this fatal compile error is one of the main advantages of using the constants inter-face, interface,
face, since you'll immediately know if you mistype a color name.
No name for escape sequence %s
(F) The ANSI escape sequence passed to uncolor() contains escapes which aren't recognized and
can't be translated to names.
ENVIRONMENT
ANSI_COLORS_DISABLED
If this environment variable is set, all of the functions defined by this module (color(), col-ored(), colored(),
ored(), and all of the constants not previously used in the program) will not output any escape
sequences and instead will just return the empty string or pass through the original text as
appropriate. This is intended to support easy use of scripts using this module on platforms that
don't support ANSI escape sequences.
For it to have its proper effect, this environment variable must be set before any color con-stants constants
stants are used in the program.
RESTRICTIONS
It would be nice if one could leave off the commas around the constants entirely and just say:
print BOLD BLUE ON_WHITE "Text\n" RESET;
but the syntax of Perl doesn't allow this. You need a comma after the string. (Of course, you may
consider it a bug that commas between all the constants aren't required, in which case you may feel
free to insert commas unless you're using $Term::ANSIColor::AUTORESET.)
For easier debuging, you may prefer to always use the commas when not setting $Term::ANSI-Color::AUTORESET $Term::ANSIColor::AUTORESET
Color::AUTORESET so that you'll get a fatal compile error rather than a warning.
NOTES
The codes generated by this module are standard terminal control codes, complying with ECMA-48 and
ISO 6429 (generally referred to as "ANSI color" for the color codes). The non-color control codes
(bold, dark, italic, underline, and reverse) are part of the earlier ANSI X3.64 standard for control
sequences for video terminals and peripherals.
Note that not all displays are ISO 6429-compliant, or even X3.64-compliant (or are even attempting to
be so). This module will not work as expected on displays that do not honor these escape sequences,
such as cmd.exe, 4nt.exe, and command.com under either Windows NT or Windows 2000. They may just be
ignored, or they may display as an ESC character followed by some apparent garbage.
Jean Delvare provided the following table of different common terminal emulators and their support
for the various attributes and others have helped me flesh it out:
clear bold dark under blink reverse conceal
------------------------------------------------------------------------xterm -----------------------------------------------------------------------xterm
xterm yes yes no yes bold yes yes
linux yes yes yes bold yes yes no
rxvt yes yes no yes bold/black yes no
dtterm yes yes yes yes reverse yes yes
teraterm yes reverse no yes rev/red yes no
aixterm kinda normal no yes no yes yes
PuTTY yes color no yes no yes no
Windows yes no no no no yes no
Cygwin SSH yes yes no color color color yes
Mac Terminal yes yes no yes yes yes yes
Windows is Windows telnet, Cygwin SSH is the OpenSSH implementation under Cygwin on Windows NT, and
Mac Terminal is the Terminal application in Mac OS X. Where the entry is other than yes or no, that
emulator displays the given attribute as something else instead. Note that on an aixterm, clear
doesn't reset colors; you have to explicitly set the colors back to what you want. More entries in
this table are welcome.
Note that codes 3 (italic), 6 (rapid blink), and 9 (strikethrough) are specified in ANSI X3.64 and
ECMA-048 but are not commonly supported by most displays and emulators and therefore aren't supported
by this module at the present time. ECMA-048 also specifies a large number of other attributes,
including a sequence of attributes for font changes, Fraktur characters, double-underlining, framing,
circling, and overlining. As none of these attributes are widely supported or useful, they also
aren't currently supported by this module.
SEE ALSO
ECMA-048 is available on-line (at least at the time of this writing) at <http://www.ecma-interna-
tional.org/publications/standards/ECMA-048.HTM.
ISO 6429 is available from ISO for a charge; the author of this module does not own a copy of it.
Since the source material for ISO 6429 was ECMA-048 and the latter is available for free, there seems
little reason to obtain the ISO standard.
The current version of this module is always available from its web site at
<http://www.eyrie.org/~eagle/software/ansicolor/. It is also part of the Perl core distribution as
of 5.6.0.
AUTHORS
Original idea (using constants) by Zenin, reimplemented using subs by Russ Allbery <rra@stan-
ford.edu>, and then combined with the original idea by Russ with input from Zenin. Russ Allbery now
maintains this module.
COPYRIGHT AND LICENSE
Copyright 1996, 1997, 1998, 2000, 2001, 2002 Russ Allbery <rra@stanford.edu> and Zenin. This program
is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
perl v5.8.8 2001-09-21 Term::ANSIColor(3pm)
|