Score:0

Ubuntu

sed with ANSI color escapes fail

Bruno Henrique Peixoto

6/7/23, 6:30 PM

I do not know why this does not work:

echo -e "$(echo "This is an uncolored text" | sed "s/{This is an uncolored text}/{This is an \033[0;34uncolored text\033[0m}/g")"

but this works well:

echo "$(echo "Hello World" | sed "s/Hello/Hi/g")"

May you explain to me?

0 + 0

command-line

sed

text-processing

Bodo

6/7/23, 7:29 PM

Please [edit] your question and explain what exactly you mean with "this does not work". What actual output do you get? What do you want to get?

Bruno Henrique Peixoto

6/7/23, 7:43 PM

The following command: start_command echo "this is an uncolored text" | sed 's/This is an uncolored text/This is an \\033\[0;34muncolored text\\033\[0m/g' end_commend still does not work

Bruno Henrique Peixoto

6/7/23, 7:48 PM

Could you paste the final result. I do not get it only by substituting ```[``` by ```\[```

Bruno Henrique Peixoto

6/7/23, 8:27 PM

The original problem takes an uncolored string and substitutes it by it colored one. However, as you can see, the colored version lacks some backslashes.

Bruno Henrique Peixoto

6/7/23, 9:01 PM

Problem solved!

Score:2

Ubuntu

steeldriver

6/7/23, 9:11 PM

There are a number of issues.

First, the braces {...} in your sed expression are not matched by anything in the input. In a sed Basic Regular Expression, braces are literal, while in an Extended Regular Expression they surround a quantifier of the form {n,m}. They are never used for grouping.

Second, your color sequence is malformed - the opening needs to be \033[0;34m rather than \033[0;34

Third, the backslash character \ is special in sed - in particular, a backslash followed by a decimal digit on the RHS of a substitution is a backreference to a capture group; at least in GNU sed, \0 refers to the whole captured LHS equivalent to the special replacement token & so for example

$ echo foo | sed 's/foo/\033bar/'
foo33bar

To pass a literal \ to the outer echo -e you'd need \\ inside the sed replacement string.

Finally, \ is also special to the shell, so inside "soft" double quotes needs an additional backslash. So either:

echo -e "$(echo "This is an uncolored text" | 
  sed "s/This is an uncolored text/This is an \\\033[0;34muncolored text\\\033[0m/")"

or (replacing the inner double quotes with 'strong' single quotes):

echo -e "$(echo "This is an uncolored text" | 
  sed 's/This is an uncolored text/This is an \\033[0;34muncolored text\\033[0m/')"

Note that you don't need the g modifier to make a single replacement per line.

0 + 0

Bruno Henrique Peixoto

6/7/23, 9:17 PM

I worked my way out. Take a look at the answer below.

Score:0

Ubuntu

Bruno Henrique Peixoto

6/7/23, 9:17 PM

My worked out solution:

#!/bin/bash

colored_text='this is a \\033[0;34mtext\\033[0m'
uncolored_text='this is a text'

printf %b\\n "$(sed "s/$uncolored_text/$colored_text/" <<< "$uncolored_text")"

0 + 0

Bruno Henrique Peixoto

6/7/23, 10:09 PM

Thanks, bac0n! It smells good.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: sed with ANSI color escapes fail

TH: sed กับ ANSI color Escapes ล้มเหลว

RO: sed cu scăpările de culoare ANSI eșuează

RU: sed с экранированием цвета ANSI не работает

VI: sed với thoát màu ANSI không thành công

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