BSD vs GNU Commands

sed -i requires extension argument: sed -i '' 's/a/b/' file — empty string for no backup, Linux doesn't need it
find doesn't support -printf — use -exec stat or xargs with stat -f instead
date uses different format flags: date -j -f '%Y-%m-%d' '2024-01-15' '+%s' — -j prevents setting time
grep -P (Perl regex) doesn't exist — use grep -E (extended) or install ggrep via Homebrew
xargs defaults to /usr/bin/echo not the command — always specify the command explicitly
readlink -f doesn't exist — use realpath or python3 -c "import os; print(os.path.realpath('path'))"

Homebrew Paths

Apple Silicon: /opt/homebrew/bin, /opt/homebrew/lib
Intel: /usr/local/bin, /usr/local/lib
Check architecture: uname -m returns arm64 or x86_64
Homebrew doesn't add to PATH automatically — check ~/.zprofile for eval line
Running x86 binaries: arch -x86_64 /bin/bash then install/run Intel-only tools