How to transfer characters between uppercase and lowercase with sed
问题 For example, my src.tex is SectionType *p = NULL; and I want it change to section_type *p = NULL; what I want to do is just change the SectionType , but remains the NULL unchanged, I used y/[A-Z]/[a-z] , but this will change all the line. My sed do not support \L,\l,\U and \u functions, it version is 3.* and distributed under FSF, not GNU, may be GNU's works well with this functions, but at the time I could not adopt the GNU's because I'm working in msys and there is no GNU package. Is there