When writing a shell script the robustness/reliabilty can be inferred from it's scope: 1. Uses shell-only commands (echo, for) - most robust; but things like b

When writing a shell script the robustness/reliabilty can be inferred from it's scope: 1. Uses shell-only commands (echo, for) - most robust; but things like basename/dirname and regex's vary by shell (sh, bash, zsh, ksh) 2. Uses /bin - might run into missing a binary but not likely, still robust and allows a richer set of tools (e.g., uname, chmod and admin-ish things live in /bin) 3. Uses /usr/bin - runs risk if missing packages, likely not very robust (packages drop things in here, like gzip, yacc, gcc) 4. Uses /usr/local/bin or /opt/local/bin - definitely requires package installs, least robust