See also: Userspace Index, Kernel Syscall

usr/sh contains the shell executable used for interactive command execution and userspace process launching.

Features

  • Built-in commands: exit [code], cd [dir], help

  • Variable assignment: VAR=value syntax

  • Variable expansion: $VAR substitution in tokens

  • PATH lookup: Searches $PATH for executables

  • I/O redirection: < (input), > (output), >> (append)

  • Pipelines: | operator with proper fork/exec/pipe plumbing

  • Chaining: && conditional command execution

  • Signal handling: SIGINT is ignored (children handle it)

Implementation

  • 755 lines of C (sh.c)

  • Exercises key process and file syscall paths from userspace

  • Acts as the default interactive userspace application

Current Status

The shell is structurally complete. The main() function currently returns 0 (the init/loop functions are commented out), pending integration with the full init process flow.

Revision History

v2.0

Updated for v0.28: added feature list with built-in commands, I/O redirection, pipelines, PATH lookup; noted current status

v1.0

Initial shell summary