Putting It All Together

Every piece you've built combines into the canonical shell loop:

The "putting it together" exercise is to drive ALL the pieces with one sample workflow: variable assignments, glob, pipe, redirect, history.

Production extras:

• Job control — backgrounding (&), fg, bg, jobs
• Aliases — pre-tokenization expansion
• Functions — name() { ... } reusable shell snippets
• Subshells — (cmd) runs in a forked child
• Command substitution — $(cmd) or backticks; runs cmd, replaces with stdout
• Process substitution — <(cmd) exposes a pipe as a virtual filename
• Readline editing — Ctrl-A, Ctrl-E, Ctrl-W, etc.
• Tab completion — context-aware suggestions

Now you understand the moving parts behind bash, zsh, fish, dash, and the dozens of other shells. The exec model has barely changed since 1970 — the polish is in everything around it.