Implement a User-Space Shell with Process and Signal Handling
Overview
What this challenge is about.
Implement a shell in C (no shell helpers, just POSIX system calls). Required features: read a line, parse it into commands + arguments, handle pipelines with arbitrary chain length using pipe() + dup2() + fork() + execvp(), implement I/O redirection (<, >, >>), background jobs (&) with non-blocking wait via SIGCHLD handler that reaps zombies and prints '[1]+ Done command' messages, built-ins cd, jobs, exit (cd must run in the parent process). Handle SIGINT in foreground children only; never let the shell die. Include a Makefile, a test script with 25 cases (including the tricky ones: cd inside a pipeline, kill -9 a background job, ctrl-C interrupting only the foreground). Deliver source, Makefile, test script, and a 3-page design note explaining the trickiest decisions.
The Brief
What you'll do, and what you'll demonstrate.
Implement a POSIX-style shell in C with pipelines, redirection, background jobs, and proper signal handling against a 25-case test script.
Earning criteria — what you'll demonstrate
- Use fork/exec/wait/pipe/dup2 to implement Unix process semantics
- Handle SIGCHLD and SIGINT correctly without race conditions
- Implement built-ins that must run in the shell process (cd) vs. children (others)
- Write a test script that exercises the tricky cases, not just happy paths
Program Fit
Where this fits in your program.
Sharpens the same skills your degree expects you to demonstrate.
Skills
Skills you'll demonstrate.
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