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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.", 'yellow on_magenta'), "\n";
print "This text is normal.\n";
print colored ['yellow on_magenta'], 'Yellow on magenta.', "\n";
print colored ['red on_bright_yellow'], 'Red on bright yellow.', "\n";
print colored ['bright_red on_black'], 'Bright red on black.', "\n";
print "\n";
use Term::ANSIColor qw(uncolor);
print uncolor ('01;31'), "\n";
use Term::ANSIColor qw(colorstrip);
print colorstrip '\e[1mThis is bold\e[0m', "\n";
use Term::ANSIColor qw(colorvalid);
my $valid = colorvalid ('blue bold', 'on_magenta');
print "Color string is ", $valid ? "valid\n" : "invalid\n";
use Term::ANSIColor qw(:constants);
print BOLD, BLUE, "This text is in bold blue.\n", RESET;
use Term::ANSIColor qw(:constants);
{
local $Term::ANSIColor::AUTORESET = 1;
print BOLD BLUE "This text is in bold blue.\n";
print "This text is normal.\n";
}
use Term::ANSIColor qw(:pushpop);
print PUSHCOLOR RED ON_GREEN "This text is red on green.\n";
print PUSHCOLOR BRIGHT_BLUE "This text is bright blue on green.\n";
print RESET BRIGHT_BLUE "This text is just bright blue.\n";
print POPCOLOR "Back to red on green.\n";
print LOCALCOLOR GREEN ON_BLUE "This text is green on blue.\n";
print "This text is red on green.\n";
{
local $Term::ANSIColor::AUTOLOCAL = 1;
print ON_BLUE "This text is red on blue.\n";
print "This text is red on green.\n";
}
print POPCOLOR "Back to whatever we started as.\n";
DESCRIPTION
This module has two interfaces, one through color() and colored() and the other through
constants. It also offers the utility functions uncolor(), colorstrip(), and
colorvalid(), which have to be explicitly imported to be used (see "SYNOPSIS").
Supported Colors
Terminal emulators that support color divide into two types: ones that support only eight
colors, and ones that support sixteen. This module provides both the ANSI escape codes
for the "normal" colors, supported by both types, as well as the additional colors
supported by sixteen-color emulators. These colors are referred to as ANSI colors 0
through 7 (normal) and 8 through 15.
Unfortunately, interpretation of colors 0 through 7 often depends on whether the emulator
supports eight colors or sixteen colors. Emulators that only support eight colors (such
as the Linux console) will display colors 0 through 7 with normal brightness and ignore
colors 8 through 15, treating them the same as white. Emulators that support 16 colors,
such as gnome-terminal, normally display colors 0 through 7 as dim or darker versions and
colors 8 through 15 as normal brightness. On such emulators, the "normal" white (color 7)
usually is shown as pale grey, requiring bright white (15) to be used to get a real white
color. Bright black usually is a dark grey color, although some terminals display it as
pure black. Some sixteen-color terminal emulators also treat normal yellow (color 3) as
orange or brown, and bright yellow (color 11) as yellow.
Following the normal convention of sixteen-color emulators, this module provides a pair of
attributes for each color. For every normal color (0 through 7), the corresponding bright
color (8 through 15) is obtained by prepending the string "bright_" to the normal color
name. For example, "red" is color 1 and "bright_red" is color 9. The same applies for
background colors: "on_red" is the normal color and "on_bright_red" is the bright color.
Capitalize these strings for the constant interface.
There is unfortunately no way to know whether the current emulator supports sixteen colors
or not, which makes the choice of colors difficult. The most conservative choice is to
use only the regular colors, which are at least displayed on all emulators. However, they
will appear dark in sixteen-color terminal emulators, including most common emulators in
UNIX X environments. If you know the display is one of those emulators, you may wish to
use the bright variants instead. Even better, offer the user a way to configure the
colors for a given application to fit their terminal emulator.
Support for colors 8 through 15 (the "bright_" variants) was added in Term::ANSIColor 3.0.
Function Interface
The function interface uses attribute strings to describe the colors and text attributes
to assign to text. The recognized non-color attributes are clear, reset, bold, dark,
faint, underline, underscore, blink, reverse, and concealed. Clear and reset (reset to
default attributes), dark and faint (dim and saturated), and underline and underscore are
equivalent, so use whichever is the most intuitive to you.
Note that not all attributes are supported by all terminal types, and some terminals may
not support any of these sequences. Dark and faint, blink, and concealed in particular
are frequently not implemented.
The recognized normal foreground color attributes (colors 0 to 7) are:
black red green yellow blue magenta cyan white
The corresponding bright foreground color attributes (colors 8 to 15) are:
bright_black bright_red bright_green bright_yellow
bright_blue bright_magenta bright_cyan bright_white
The recognized normal background color attributes (colors 0 to 7) are:
on_black on_red on_green on yellow
on_blue on_magenta on_cyan on_white
The recognized bright background color attributes (colors 8 to 15) are:
on_bright_black on_bright_red on_bright_green on_bright_yellow
on_bright_blue on_bright_magenta on_bright_cyan on_bright_white
For any of the above listed attributes, case is not significant.
Attributes, once set, last until they are unset (by printing the attribute "clear" or
"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.
color(ATTR[, ATTR ...])
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. color() throws an exception if given an invalid attribute.
colored(STRING, ATTRIBUTES)
colored(ATTR-REF, STRING[, STRING...])
As an aid in resetting colors, 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 contains newlines and you're using background colors, since a background
color that persists across a newline is often interpreted by the terminal as providing
the default background color for the next line. Programs like pagers can also be
confused by attributes that span lines. Normally you'll want to set
$Term::ANSIColor::EACHLINE to "\n" to use this feature.
uncolor(ESCAPE)
uncolor() performs the opposite translation as color(), turning escape sequences into
a list of strings corresponding to the attributes being set by those sequences.
colorstrip(STRING[, STRING ...])
colorstrip() removes all color escape sequences from the provided strings, returning
the modified strings separately in array context or joined together in scalar context.
Its arguments are not modified.
colorvalid(ATTR[, ATTR ...])
colorvalid() takes attribute strings the same as color() and returns true if all
attributes are known and false otherwise.
Constant Interface
Alternately, if you import ":constants", you can use the following constants directly:
CLEAR RESET BOLD DARK
FAINT UNDERLINE UNDERSCORE BLINK
REVERSE CONCEALED
BLACK RED GREEN YELLOW
BLUE MAGENTA CYAN WHITE
BRIGHT_BLACK BRIGHT_RED BRIGHT_GREEN BRIGHT_YELLOW
BRIGHT_BLUE BRIGHT_MAGENTA BRIGHT_CYAN BRIGHT_WHITE
ON_BLACK ON_RED ON_GREEN ON_YELLOW
ON_BLUE ON_MAGENTA ON_CYAN ON_WHITE
ON_BRIGHT_BLACK ON_BRIGHT_RED ON_BRIGHT_GREEN ON_BRIGHT_YELLOW
ON_BRIGHT_BLUE ON_BRIGHT_MAGENTA ON_BRIGHT_CYAN ON_BRIGHT_WHITE
These are the same as color('attribute') and can be used if you prefer typing:
print BOLD BLUE ON_WHITE "Text", RESET, "\n";
to
print colored ("Text", 'bold blue on_white'), "\n";
(Note that the newline is kept separate to avoid confusing the terminal as described above
since a background color is being used.)
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 afterward, whereas:
print BOLD, BLUE, "Text\n";
will not. If you are using background colors, you will probably want to print the newline
with a separate print statement to avoid confusing the terminal.
The subroutine interface has the advantage over the constants interface in that only two
subroutines are exported into your namespace, versus thirty-eight 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, pollute 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.
The Color Stack
As of Term::ANSIColor 2.0, you can import ":pushpop" and maintain a stack of colors using
PUSHCOLOR, POPCOLOR, and LOCALCOLOR. PUSHCOLOR takes the attribute string that starts its
argument and pushes it onto a stack of attributes. POPCOLOR removes the top of the stack
and restores the previous attributes set by the argument of a prior PUSHCOLOR. LOCALCOLOR
surrounds its argument in a PUSHCOLOR and POPCOLOR so that the color resets afterward.
When using PUSHCOLOR, POPCOLOR, and LOCALCOLOR, it's particularly important to not put
commas between the constants.
print PUSHCOLOR BLUE "Text\n";
will correctly push BLUE onto the top of the stack.
print PUSHCOLOR, BLUE, "Text\n"; # wrong!
will not, and a subsequent pop won't restore the correct attributes. PUSHCOLOR pushes the
attributes set by its argument, which is normally a string of color constants. It can't
ask the terminal what the current attributes are.
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 or PUSHCOLOR/POPCOLOR.)
For easier debugging, you may prefer to always use the commas when not setting
$Term::ANSIColor::AUTORESET or PUSHCOLOR/POPCOLOR so that you'll get a fatal compile error
rather than a warning.
It's not possible to use this module to embed formatting and color attributes using Perl
formats. They replace the escape character with a space (as documented in perlform(1)),
resulting in garbled output from the unrecognized attribute. Even if there were a way
around that problem, the format doesn't know that the non-printing escape sequence is
zero-length and would incorrectly format the output. For formatted output using color or
other attributes, either use sprintf() instead or use formline() and then add the color or
other attributes after formatting and before output.
NOTES
The codes generated by this module are standard terminal control codes, complying with
ECMA-048 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 faint under blink reverse conceal
------------------------------------------------------------------------
xterm yes yes no yes yes 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 (strike-through) 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 <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 AT 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, 2005, 2006, 2008, 2009, 2010, 2011 Russ
Allbery <rra AT stanford.edu> and Zenin. This program is free software; you may redistribute
it and/or modify it under the same terms as Perl itself.
PUSHCOLOR, POPCOLOR, and LOCALCOLOR were contributed by openmethods.com voice solutions.
perl v5.16.3 2013-03-04 Term::ANSIColor(3pm)
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