Bash
PHP String Functions in Bash: A Cheat Sheet
The index to the Bash function library: every PHP string function with its pure-Bash equivalent, short tested snippets, and when to use awk or sed instead.
Topic
parameter-expansion
Bash
str_pad() in Bash: Pad a String to a Fixed Length
PHP-compatible str_pad() in pure Bash, when printf "%-10s" and %05d are enough, and why multibyte text breaks the alignment of your columns.
Bash
str_replace() in Bash: Replace Text in a String
Replace text in a Bash string without sed: ${s//search/replace}, anchored replacements, why you must quote the search, and what Bash 5.2 did to &.
Bash
trim() in Bash: Strip Leading and Trailing Whitespace
PHP-style trim(), ltrim() and rtrim() in pure Bash with parameter expansion, plus why the popular read trick quietly removes your backslashes.
Bash
strlen() in Bash: Get the Length of a String
Bash's ${#var} counts characters, PHP's strlen() counts bytes. A clean strlen() function, a strbytes() companion, and the locale traps in between.
Bash
strtolower() in Bash: Convert a String to Lowercase
A strtolower() for Bash 4 and the stock macOS Bash 3.2, why ${var,,} depends on your locale, and when declare -l, tr, awk or nocasematch fit better.
Bash
strtoupper() in Bash: Convert a String to Uppercase
A strtoupper() that works on Bash 4+ and macOS's Bash 3.2, plus ${var^^pattern} for uppercasing only some characters and declare -u for variables.
Bash
dirname() in Bash: Get the Directory Part of a Path
Get the directory part of a path in pure Bash, matching coreutils dirname on trailing slashes, bare names and the root, without starting a process.
Bash
basename() in Bash: Strip the Directory From a Path
Get the file name from a path with parameter expansion, matching coreutils basename on trailing slashes, "/" and suffixes, without starting a process.
Bash
ucfirst() in Bash: Uppercase the First Character
A ucfirst() for Bash 4+ and macOS's Bash 3.2, what "first character" really means, and how to get "Hello" from "hELLO" or " hello".