[SOLVED] Cse 3100 systems programming lab #5

Part 1. (100 points) run2 should use the fork and exec functions to run two commands specified on the
command line. The arguments passed to run2 are stored in the array argv. The first executable is argv[1]
and it takes one, and only one, argument, which is in argv[2]. The second executable is argv[3], and the
rest of arguments, if any, are arguments to argv[3].
In the following example, the two commands are cat Makefile and ls a b.
$ ./run2 cat Makefile ls a b
There are multiple functions in the exec family of functions, which behave in slightly different ways. You
should use execlp to run the first command, and execvp to run the second command. You should read the
manpage for exec, and understand why these variants are sensible choices here.
If any functions like fork() fail, report the error using perror() and exit from the process. The parameter
to perror() is the function name followed by parentheses, as in the following examples.
perror(“fork()”);
perror(“execlp()”);
For each child process successfully created, the parent process waits for the child process to exit and
prints out the exit status of the child process using the following format string:
“exited=%d exitstatus=%d
”
The first number is from WIFEXITED, and the second is from WEXITSTATUS. Study the demo code
or the manuals to learn WIFEXITED and WEXITSTATUS.
Below are some examples of using run2. You may have more creative ways to use the program.
$ ./run2 vi run2.c make
$ ./run2 touch run2.c make run2
$ ./run2 echo 1 ./run2 echo 2 ./run2 echo 3 ls *