site/docs/3.7/cmds/string-replace.html
string replace [-a | --all] [-f | --filter] [-i | --ignore-case][-r | --regex] [-q | --quiet] PATTERN REPLACEMENT [STRING ...]
string replace is similar to string match but replaces non-overlapping matching substrings with a replacement string and prints the result. By default, PATTERN is treated as a literal substring to be matched.
If -r or --regex is given, PATTERN is interpreted as a Perl-compatible regular expression, and REPLACEMENT can contain C-style escape sequences like t as well as references to capturing groups by number or name as $n or ${n}.
If you specify the -f or --filter flag then each input string is printed only if a replacement was done. This is useful where you would otherwise use this idiom: a_cmd | string match pattern | string replace pattern new_pattern. You can instead just write a_cmd | string replace --filter pattern new_pattern.
Exit status: 0 if at least one replacement was performed, or 1 otherwise.
\>\_ string replace is was 'blue is my favorite'blue was my favorite\>\_ string replace 3rd last 1st 2nd 3rd1st2ndlast\>\_ string replace -a ' ' \_ 'spaces to underscores'spaces\_to\_underscores
\>\_ string replace -r -a '[^\d.]+' ' ' '0 one two 3.14 four 5x'0 3.14 5\>\_ string replace -r '(\w+)\s+(\w+)' '$2 $1 $$' 'left right'right left $\>\_ string replace -r '\s\*newline\s\*' '\n' 'put a newline here'put ahere