Bash – How to capture text formatting in bash

bashcolorsescape-charactersscriptingshell-script

The following shell script works but removes colored formatting generated by rspec:

#!/bin/bash
OUTPUT=`rspec`
echo "$OUTPUT"

How to preserve the colors?

Best Answer

It's common for programs with colorized output to disable it if they're not being run directly in a TTY, since you might be piping the output to a log file or to another process that expects plain text. Typically the programs offer a switch to manually force colors enabled, and rspec has one (--color), but for some reason it ignores it if you're not running in a TTY, which is really unusual behavior.

I think your only options are to edit rspec to take out that check (see def color in rspec-core-2.11.1/lib/rspec/core/configuration.rb), or run it within a program that will trick it into thinking it has a TTY, like expect

Related Solutions

Bash – Color script output only when invoked from interactive shell

It is common for unix application that do support colour output (such as grep and ls) to have a command line option as well as possibly automatic detection.

looking at man ls we see

--color[=WHEN]
              colorize the output.  WHEN defaults to `always' or can be `never' or `auto'.  More info below

So by default ls will always use colour, notice the auto option.

man grep shows similar

 --color[=WHEN], --colour[=WHEN]
              <snipped> WHEN is never, always, or auto.

If the auto option is enabled (which for your application could be the default) then something like the following answer (suggested by Gilles) may be what you are looking for https://unix.stackexchange.com/a/10065/4635

That is if your output is a terminal and supports colour, and the user hasn't disabled it you should use color. Of course the user using always or never skips this check.

I find it useful if programs have a --color=always even if they support automatic detection, as this means that I can force colour usage 'when I know better' (say my destination isn't a terminal but I know it supports colour'). On some systems I have an alias for ls to ls --color=always.

Shell – Bash – Convert escape character colored text to BBCode

Noting a comment about "Easy using awk", that would be relative to sed.

OP was describing a not-very-well documented feature of logcat (see commit) which tells logcat to assign hardcoded-colors to each line based on the log entry's priority.

There are other choices, such as logcat-color, PID cat and coloredlogcat which let you color different fields, e.g., raising the possibility of multiple colors per line.

Here's an awk script which recognizes the hardcoded logcat colors, but allows multiple colors per line:

#!/usr/bin/awk -f
BEGIN {
        colors["0"]        = "Black";
        colors["38;5;40"]  = "Green";
        colors["38;5;196"] = "Red";
        colors["38;5;75"]  = "Blue";
        colors["38;5;166"] = "Sienna";
        colors["38;5;231"] = "DarkSlateGray";
        color = "";
        last = "";
        this = "";
        save = "";
}
/\033/ {
        done = "";
        while ( $0 ~ /\033\[[;0-9]*m/ ) {
                mark = match($0, /\033\[[;0-9]*m/ );
                if ( mark > 1 ) { done = done substr($0, 1, mark - 1); }
                item = substr($0, RSTART + 2, RLENGTH - 3);
                $0 = substr($0, RSTART + RLENGTH);
                if ( match($0, /^\033\[[;0-9]*m/ ) > 0 ) continue;
                color = colors[item];
                if ( done == "" ) this = color;
                if ( item == "0" ) color = "";
                if ( color == "" ) {
                        if ( $0 != "" ) last = color;
                        $0 = "[/COLOR]" $0;
                } else if (color != last) {
                        $0 = "[COLOR=\"" color "\"]" $0;
                        last = color;
                }
        }
        $0 = done $0;
        if ( last != "" ) $0 = $0 "[/COLOR]";
}
{
        if ( NR > 1 ) {
                if ( this == last) sub("\[/COLOR\]$", "", save);
                print save;
        }
        save = $0;
}
END {
        if ( NR > 0 ) print save;
}

With the original example:

^[[0m^[[38;5;231mV/Zygote  ( 4666): Switching descriptor 55 to /dev/null
^[[0m^[[38;5;231mV/Zygote  ( 4666): Switching descriptor 9 to /dev/null
^[[0m^[[38;5;40mI/ggheart ( 1111): onStop
^[[0m^[[38;5;40mI/Test    ( 1111): onStop
^[[0m^[[38;5;75mD/ActivityThread( 4666): handleBindApplication:com.mxtech.videoplayer.ad
^[[0m^[[38;5;75mD/ActivityThread( 4666): setTargetHeapUtilization:0.75
^[[0m^[[38;5;75mD/ActivityThread( 4666): setTargetHeapMinFree:2097152

you would get the requested output:

[COLOR="DarkSlateGray"]V/Zygote  ( 4666): Switching descriptor 55 to /dev/null
V/Zygote  ( 4666): Switching descriptor 9 to /dev/null
[COLOR="Green"]I/ggheart ( 1111): onStop
I/Test    ( 1111): onStop
[COLOR="Blue"]D/ActivityThread( 4666): handleBindApplication:com.mxtech.videoplayer.ad
D/ActivityThread( 4666): setTargetHeapUtilization:0.75
D/ActivityThread( 4666): setTargetHeapMinFree:2097152[/COLOR]

but changing the input to

^[[0m^[[38;5;231mV/Zygote  ( 4666): Switching descriptor 55 to /dev/null
^[[0m^[[38;5;231mV/Zygote  ( 4666): Switching descriptor 9 to /dev/null
^[[0m^[[38;5;40mI/ggheart ( ^[[38;5;75mI/ggheart 1111^[[0m): onStop
^[[0m^[[38;5;40mI/Test    ( 1111): onStop
^[[0m^[[38;5;75mD/ActivityThread( 4666): handleBindApplication:com.mxtech.videoplayer.ad
^[[0m^[[38;5;75mD/ActivityThread( 4666): setTargetHeapUtilization:0.75
^[[0m^[[38;5;75mD/ActivityThread( 4666): setTargetHeapMinFree:2097152

gives this result:

[COLOR="DarkSlateGray"]V/Zygote  ( 4666): Switching descriptor 55 to /dev/null
V/Zygote  ( 4666): Switching descriptor 9 to /dev/null[/COLOR]
[COLOR="Green"]I/ggheart ( [COLOR="Blue"]I/ggheart 1111[/COLOR]): onStop
[COLOR="Green"]I/Test    ( 1111): onStop
[COLOR="Blue"]D/ActivityThread( 4666): handleBindApplication:com.mxtech.videoplayer.ad
D/ActivityThread( 4666): setTargetHeapUtilization:0.75
D/ActivityThread( 4666): setTargetHeapMinFree:2097152[/COLOR]

Best Answer

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Bash – Color script output only when invoked from interactive shell

Shell – Bash – Convert escape character colored text to BBCode

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