The first known correct software solution to the critical-section problem for two processes was developed by Dekker. The two processes, P0 and P1, share the following variables:

boolean flag[2]; / initially false /
int turn;

The structure of process Pi (i == 0 or 1) is shown in Figure 5.21. The other process is Pj (j == 1 or 0). Prove that the algorithm satisfies all three requirements for the critical-section problem.

FIGURE 5.21
do {
flag[i] = true;

while (flag[j]) {

if (turn == j) {
flag[i] = false;
while (turn == j) ; / do nothing /
flag[i] = true;
}
}

/ critical section /

turn = j;
flag[i] = false;

/ remainder section /

} while (true);

Write the command that can be used to answer the following questions. (hint: try each out on the system to check your results.) a. find all files on the system that have the word test" as part of their filename. b. search the path variable for the pathname to the awk command. c. find all files in the /usr directory and subdirectories that are larger than 50 kilobytes in size. d. find all files in the /usr directory and subdirectories that are less than 70 kilobytes in size. e. find all files in the / directory and subdirectories that are symbolic links. f. find all files in the /var directory and subdirectories that were accessed less than 60 minutes ago. g. find all files in the /var directory and subdirectories that were accessed less than six days ago. h. find all files in the /home directory and subdirectories that are empty. i. find all files in the /etc directory and subdirectories that are owned by the group bin."