Operating Systems Project 5

turnin code: cs_p5


Write a program that forks one process. Have the new process execve
the program named /usr/bin/bc. Use dup2 and pipes to establish a way
for the original process to pass stdin to bc, and to capture its stdout.

It would be a good idea to do alarm(60) in both processes again.

The original process should read lines of input from a file named as the
first command-line arg. Subsequent command-line args should be handed
to bc as if they were entered on its command-line; there will be no more
than 3.

Each line should be handed to the bc process on its stdin via a pipe,
the line input printed, and output (if any) printed like this:

in: line_of_input_from_file
bc: output_printed_by_bc # this may be 0 or several lines
blank_line

Note that bc will not always print something, e.g. it will not reply to:

a = 0

The select system call can be useful to determine if data is available
on a descriptor. Do not pause more than 1 second for data here.


I will run tests by typing commands like this:

./p5 infilename1
./p5 infilename2 -l # the -l will be passed as arg to bc


TURNIN info:
You should submit a tar file of a directory which contains all of the
required files (makefile, C source files, header files, etc).
Sample tar command to create a tar file from a dir named p5dir:
tar cvf p5.tar ./p5dir ## do *NOT* use full pathname of the dir
After un-tarring your project, I will cd to the dir containing
it and type:
rm -rf p5
rm -f *.o
make