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how to apply ANSI escape codes when a backslash precedes the escape code
I am using ANSI escape codes in a shell script to colorize some parts of a string.
For example, here I add the text NOTE with a red background color at the end of $var:
$ var='test'
$ echo $var'\e[41mNOTE\e[0m'
This works as intended.
However, if $var has a backslash at the end, this technique won't work because the backslash at the end of $var and at the beginning of the first escape code are joined together to form \\, which is interpreted as a single backslash character:
$ var='test\'
$ echo $var'\e[41mNOTE\e[0m'
The variable $var is obtained from lines of various files, and widely varies.
So ideally, I am looking for a solution that does not require checking the last character of $var.
2 answers
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printf and tput can also be used to handle the coloring without worrying about the backslash issue. tput is a command that can be used to set terminal attributes, including colors, and it handles escape sequences more cleanly.
printf "%s$(tput setaf 9)NOTE$(tput sgr0)\n" "${var}"
This avoids the problem of backslashes being misinterpreted and works regardless of the content of $var.
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