shell-c

A POSIX-compliant Unix shell implemented in C.

Features

Pipelines — arbitrary-length pipelines (cmd1 | cmd2 | cmd3)
I/O redirection — <, >, >>
Background execution — trailing &
Signal handling — Ctrl+C and Ctrl+Z reach the foreground pipeline, not the shell; background children are reaped asynchronously via SIGCHLD
Process groups — each pipeline runs in its own process group so signals reach every stage
Built-ins — cd, exit, export, history
Command history — ring buffer of the last 100 commands
Trace mode — --trace logs every fork, exec, and pipe to stderr

make

Requires a C11 compiler and POSIX.1-2008.

./shell-c           # interactive mode
./shell-c --trace   # with execution tracing

Command	Description
`cd [dir]`	Change directory; defaults to `$HOME`
`exit [code]`	Exit with optional status code
`export VAR=VALUE`	Set an environment variable
`history`	Print command history