Enable bash output color with Lua script

Question

I have several Lua scripts that run experiences and output a lot of information, in text files and in the console. I'd like to add some colors in the console output, to make it more readable.

I know that it's possible to color the output of bash scripts using the ANSI escape sequences. For example :

$ echo -e "This is red->\e[00;31mRED\e[00m"

I tried to do the same in Lua :

$ lua -e "io.write('This is red->\\e[00;31mRED\\e[00m\n')"

but it does not work. I also tried with print() instead of io.write(), but the result is the same.

Answer 1

It can certainly be done in Lua; the trick is just getting the escape sequence right. You can use string.char to write a specific ASCII value out:

$ echo -e '\E[37;44m'"\033[1mHello\033[0m" #  white on blue
Hello   
$ echo -e '\E[37;44m'"\033[1mHello\033[0m" | xxd # check out hex dump of codes
0000000: 1b5b 3337 3b34 346d 1b5b 316d 4865 6c6c  .[37;44m.[1mHell
0000010: 6f1b 5b30 6d0a                           o.[0m.
$ lua -e "for _,i in ipairs{0x1b,0x5b,0x33,0x37,0x3b,0x34,0x34,0x6d,\
0x1b,0x5b,0x31,0x48,0x65,0x6c,0x6c,0x6f,0x1b,0x5b,0x30,0x6d,0x0a} \
do io.write(string.char(i)) end"  # prints out "Hello" in white on blue again
Hello

Answer 2

lua -e "print('This is red->\27[31mred\n')"

Note the \27. Whenever Lua sees a \ followed by a decimal number, it converts this decimal number into its ASCII equivalent. I used \27 to obtain the bash \033 ESC character. More info here.