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Term::ANSIColor(3)
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 intuitive 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.
Alternately, 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 colorize.
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 confused 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, UNDERLINE, 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 variable 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 interface, 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(), colored(), 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 constants 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::ANSIColor::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 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
Windows is Windows telnet, and Cygwin SSH is the OpenSSH implementation
under Cygwin on Windows NT. 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-international.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@stanford.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 <zenin@bawdycaste.org>. This program is free
software; you may redistribute it and/or modify it under the same terms as
Perl itself.
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