To perform a case-insensitive search and replacement using the sed command in Unix or Linux, you can use the -i option to enable case-insensitive matching, and the \L and \U escape sequences to convert the matched text to lowercase or uppercase, respectively.
The sed command is a utility that is used to edit and manipulate text streams. It can be used to search for a pattern in a file and replace it with a different string.
To perform a case-insensitive search and replacement using sed, you can use the following syntax:
sed -i "s/pattern/replacement/ig" file.txt
This will search for the pattern string in the file.txt file and replace it with the replacement string, ignoring the case of the matched text.
The -i option enables in-place editing of the file, so the changes are made directly to the file.txt file. The s/pattern/replacement/ syntax is the sed command to search and replace a pattern with a replacement string. The i flag enables case-insensitive matching.
To convert the matched text to lowercase or uppercase, you can use the \L and \U escape sequences in the replacement string. For example:
sed -i "s/pattern/\Lreplacement/ig" file.txt
This will replace the pattern string with the replacement string in lowercase.
sed -i "s/pattern/\Ureplacement/ig" file.txt
This will replace the pattern string with the replacement string in uppercase.
For more information about the sed command and its options, you can consult the documentation for your specific Unix or Linux system.