Term::ANSIColor - Color screen output using ANSI escape sequences
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(: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";
This module has two interfaces, one through color() and colored() and the
other through constants.
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).
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, 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.
- 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.
- 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).
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.
Jean Delvare provided the following table of different common terminal
emulators and their support for the various attributes:
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
Where the entry is other than yes or no, that emulator interpret 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.
Original idea (using constants) by Zenin (zenin@best.com), reimplemented
using subs by Russ Allbery (rra@stanford.edu), and then combined with the
original idea by Russ with input from Zenin.
