There are built-in shell variables that the shell itself sets and manages, giving scripts a standard way to read arguments, argument counts, exit status, process IDs, and execution state. They are guaranteed to exist and behave consistently in POSIX-compliant shells such as sh, dash, and ksh, and also in bash and zsh when run in POSIX mode, which is why they are the foundation of portable, predictable shell scripts across Unix-like systems. Here are a list of built-in shell variables😎👆 Find a