My guideline is and remains: what type of person might ask the question, be interested in the topic and know the answer?
- Topics for users and administrators: ask here.
- Topics for programmers: ask on Stack Overflow.
My judgements on all the cases that have arisen is based on this guideline. Scripting and text processing with shells, awk, etc., are commonly performed by power users and administrators and therefore are on-topic here. (They are also programming tasks and therefore on-topic on SO as well.) Power users tend to have a working knowledge of some low-level interfaces (through strace, by reading source code that they half-understand to understand why a program is behaving, ...), so questions involving these are also ok here. Questions requiring serious knowledge of an “advanced” programming language (pointers in C, objects in Perl, etc.) are off-topic.