CS208, Monday 21 Feb 2022

Today's office hours

• 9:45-11:00 (not 10:30-11:30--I have an un-reschedulable meeting at 11)
• Available for Zooming 3:00-4:00. Slack DM me if you want to talk.

This week

• More on concurrency
• Wrap up the command shell assignment
• Start the buffer overflow assignment
• Start virtual memory

Today

• C stuff (const; variations on char *)
• Process stuff (signals, background processes)
• Probably not enough time, but maybe: trouble in multi-processing paradise

char pointers

• charstar.c
• "hello", char *p, char p[10], &c
• What's the same? What's different?
• where do these things live in memory?
• two questions you should ask yourself (in many situations):
  • what type is that thing?
  • where does that thing live in memory?
• const
• execlp(...)?

Background processes

• the ampersand
• reading the "wait" manual page
• other systems of background processes (e.g. systemd)

Unix signals

• signals.c
• man signals
• Unix reference manual sections ("man 2 read" vs. "man read"; same with "kill")

More questions about the command shell

• ?

Shared memory and problems with concurrency

• race.c
• norace.c