Question #1:

q1.1: 59

q1.2: cat apache2.strace | sed "s/(.*//" | sed "s/.* //" | sort | uniq | wc -l

q1.3: 
   mmap, newfstatat, epoll_ctl, read, getrandom


q1.4: cat apache2.strace | sed "s/(.*//" | sed "s/.* //" | sort | uniq -c | sort -n | tail -5

	(note that on Mac, the "-n" may not be necessary!!)

    982 mmap
   1001 newfstatat
   1153 epoll_ctl
   1447 read
   4223 getrandom

Question #2: 

q2.1: 28 processes   (cat apache2.strace | sed "s/ .*//" | sort -n | uniq | wc -l)

q2.2: For instance, one PID is 2071751. At line 6139 we see the syscall that returns value 2071751: clone3. Answer: clone3

q2.3: clone3 is called 27 times (cat apache2.strace| grep clone3 | wc -l). It makes sense (there is an initial process that creates 27 processes, for a total of 28)

q2.4: The stack size is passed to clone3, with value 0x7ffec0. This is in hex, and in bytes (according to the clone3 man page). It's about 8MiB (7.9996). 

Question #3:

q3.1: The first request is done at time 1684276563.701339 (line 6838), which is 1684276563.701339 - 1684276335.857725 = 227.84 seconds after the beginning of the observation period.

q3.2: There are 16 requests. Not 32 (there is a read, the request, and a write, the answer)

q3.3: cat apache2.strace| grep AWS-Logo-for-dark-150x150-1.png | grep GET | grep read | wc -l

q3.4: The strace output at line 7590 shows the writev syscall that sends back the file to the client, which happens to show the bytes in the file, in hex. The first bytes in any PNG file should be (https://en.wikipedia.org/wiki/PNG): 89 50 4E 47. Yet, what we see in the strace output is: \x89\x50\x4f\x47. The 3rd byte is corrupted. 


Question #4:

q4.1: 32 times (cat apache2.strace | grep accept4 | wc -l)

q4.2: PID 2071760 accepts all requests. It was created by process 2071734 about .5 seconds into the observation period.

q4.3: There are 32 requests. The observation period is 1684276695.178289 - 1684276335.857725 = 359.32 seconds, so the arrival rate is 32/359.32 =~ .089 requests per second.

q4.4: 20 (cat apache2.strace | grep accept4  | sed "s/.*ffff://" | sed "s/\".*//" | sort | uniq | wc -l)


Question #5:

q5.1: 9675 bytes of real data, 293 of HTTP stuff: 293/(9675+293) = 2.939%

q5.2: newfstatat

q5.3: Unix epoch time for the last modification of the file is 1683833861. Using an Unix epoch time converter gives us: May 11 2023.