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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