Shell follow-ups

/apps/sh.elf is already the default interactive shell. Pipes, redirection, &&, ||, background &, and wait shipped in PR #181. This page tracks the remaining POSIX-shaped shell work.

Parsing and expansion

• Double and single quotes with correct expansion rules.
• Backslash escapes.
• Inline NAME=VALUE command assignments.
• Command substitution with $(command).
• Positional parameters: $0 through $9, $#, $@, and $*.
• Shell PID and last background PID: $$ and $!.

Control flow

• case ... esac.
• Functions, return, and function-local variables.
• break N and continue N.
• Subshells with ( ... ).

Environment

• Pass a real envp through execve.
• Add export.
• Add shell options such as set -e, set -u, and set -x.

Job control

• Add jobs, fg, and bg.
• Add process groups and a tcsetpgrp equivalent before claiming real foreground job control.
• Add richer signal handling where job control needs it.

Smaller builtins and polish

• Add alias, unalias, type, which, getopts, and printf.
• Add cd - and tilde expansion.
• Complete command names from PATH and variables after $.

Suggested order

1. Quote-aware tokenization and escapes.
2. Real envp, export, and inline assignments.
3. Positional parameters and functions.
4. Command substitution and subshells.
5. Process groups and interactive job control.