Term::ANSIColor(3Perl Programmers Reference GuiTerm::ANSIColor(3)NAMETerm::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(: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.
color() takes any number of strings as arguments and con
siders 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, under
score, blink, reverse, concealed, black, red, green, yel
low, 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 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 send
ing 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 con
stants 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
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 con
stant 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).
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 com
mas when not setting $Term::ANSIColor::AUTORESET so that
you'll get a fatal compile error rather than a warning.
NOTES
Jean Delvare provided the following table of different
common terminal emulators and their support for the vari
ous 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.
AUTHORS
Original idea (using constants) by Zenin (zenin@best.com),
reimplemented using subs by Russ Allbery (rra@stan
ford.edu), and then combined with the original idea by
Russ with input from Zenin.
2001-02-22 perl v5.6.1 Term::ANSIColor(3)
