Bash
ucwords() in Bash: Capitalise Every Word in a String
A ucwords() for Bash that works word by word instead of char by char, preserves all whitespace, and lets you decide what counts as a word boundary.
Topic
parameter-expansion
Bash
rm_str() in Bash: Remove a Substring From a String
Delete every occurrence of a substring with one Bash parameter expansion, no sed or tr needed, and the quoting mistakes that make it go wrong.
Bash
lcfirst() in Bash: Lowercase the First Character
lcfirst() in Bash with ${var,} and a Bash 3.2 fallback, used for PascalCase to camelCase, plus a fix for names that begin with an acronym.
Bash
str_repeat() in Bash: Repeat a String N Times
A str_repeat() for Bash that stays fast at millions of copies, why the common printf trick slows down, and the two bugs in the 2009 version.