How to strip ANSI escape sequences from a variable?

Question

Weird question. When I set a variable in Bash to display as a certain color, I don\'t know how to reset it. Here is an example:

First define the color code:

Answer 1

Here is a pure Bash solution:

ERROR="${ERROR//$'\e'\[*([0-9;])m/}"

Make it a function:

# Strips ANSI codes from text
# 1: The text
# >: The ANSI stripped text
function strip_ansi() {
  shopt -s extglob # function uses extended globbing
  printf %s "${1//$'\e'\[*([0-9;])m/}"
}

See:

• Bash Shell Parameter Expansion
• Bash Pattern-Matching

Answer 2

You almost had it. Try this instead:

ERROR=$(echo "$ERROR" | sed 's%\o033\[33m%%g')

Note, however, that the use of the \oNNN escape sequence in sed is a GNU extension, and thus not POSIX compliant. If that is an issue, you should be able to do something more like:

ERROR=$(echo "$ERROR" | sed 's%'$(echo -en "\033")'\[33m%%g')

Obviously, this will only work for this one specific color (yellow), and a regex to remove any escape sequence (such as other colors, background colors, cursor positioning, etc) would be somewhat more complicated.

Also note that the -r is not required, since nothing here is using the extended regular expression syntax. I'm guessing you already know that, and that you just included the -r out of habit, but I mention it anyway just for the sake of clarity.