at least in the awks built into osx and debian have sub and gsub (and gawk adds gensub). sub(r, t, s) substitutes t for the first occurr

at least in the awks built into osx and debian have sub and gsub (and gawk adds gensub). sub(r, t, s) substitutes t for the first occurrence of the regular expression r in the string s. If s is not given, $0 is used. gsub same as sub except that all occurrences of the regular expression are replaced; sub and gsub return the number of replacements.