Prince781 / pcfsh

A simple job control shell done as a project for a class.

pcfsh

Author

Princeton Ferro

Commands Supported

Supported commands are cd, fg, bg, jobs, and exit. These are implemented according to the POSIX standards defined in the manpages (except not for cd). Type help to get a list of these commands and their usage.

How it works

1. user gives input
2. input has to be parsed and analyzed
   • parsing is done with a LL(1) grammar (see parser.h for the grammar)
   • semantic analyzer (see analyzer.h) processes the parse tree and simplifies it to a (sort of) "AST"
3. then job_exec() is called on the "AST", which figures out what programs to exec and how to redirect everything. A new object is created (struct job) representing the running job.
4. after the job finishes (if it is background, then this step happens immediately), a check is done on all job objects and some cleanup is done on finished jobs.
5. on process termination, a cleanup (via atexit(3)) is run on all jobs, and any child processes are sent SIGKILL

Testing

run with make run or make run_valgrind to check memory leaks