Homework & Coursework Questions

Originally Posted by izzy077

1. The problem statement, all variables and given/known data:
Basic Assignment
Write a program similar to the Unix "tee" command.
Program
The Unix "tee" command is used to pull out copies of a data stream. It is typically used in conjunction with pipes (analogous to a T-joint in plumbing, hence the name). It takes all data from the standard input and copies it to the standard output, but also copies it into files named as its arguments. For example, the command

cat myfile | tee a b c | lpr -P csl

would take the data coming from the cat side of the pipe and store it in the files a, b, and c, in addition to sending it on to the lpr side of the pipe.
The -a option to the "tee" command changes the functionality slightly so that instead of overwriting the output files, the data stream is appended to the output files. Your program should also implement this functionality.
Getting a line
The read() and write() functions work with file descriptors and have no understanding of lines in the file. You must write a helper function which will read input by lines.
The following function signature is recommended:

int getline(int fd, char * buffer, int max_size)

The file descriptor is the open file to be read from. The buffer is an array of characters allocated by you to hold the line. The buffer should have max_size allowable characters. The function returns the number of characters actually read.
The line returned in the buffer should NOT have the newline character stored in it.

Your program should be called "z123456.tee" where z123456 should be replaced with your z-ID.
Input
A sample input file can be found here (synclog) .
Error Checking
If any output file cannot be opened, then that file should be skipped. Remaining files should be processed.

Output

% z123456.tee
Usage: z123456.tee [-a] out_file1 [ out_file2 ...]
Sends lines of the standard input to all of the output files
and to the standard output.
The -a option will append the output to all files instead of
overwriting them.
% cat synclog | z123456.tee a b c > d
% ls -l
total 268
-rw-r--r-- 1 user user 37432 Nov 5 16:31 a
-rw-r--r-- 1 user user 37432 Nov 5 16:31 b
-rw-r--r-- 1 user user 37432 Nov 5 16:31 c
-rw-r--r-- 1 user user 37432 Nov 5 16:31 d
-rw-r--r-- 1 user user 37432 Nov 5 16:20 synclog
% diff a synclog
% cat synclog | z123456.tee -a a b c > d
% ls -l
total 388
-rw-r--r-- 1 user user 74864 Nov 5 16:34 a
-rw-r--r-- 1 user user 74864 Nov 5 16:34 b
-rw-r--r-- 1 user user 74864 Nov 5 16:34 c
-rw-r--r-- 1 user user 37432 Nov 5 16:34 d
-rw-r--r-- 1 user user 37432 Nov 5 16:20 synclog
%
2. Relevant commands, code, scripts, algorithms:

3. The attempts at a solution (include all code and scripts):
(
read(){
int getline(int fd, char * buffer, int max_size)
int fd, count;
char buffer[max_size];
fd = open("inputfile", O_RDONLY);
if (fd == -1) {
cerr << "file could not be opened\n";
exit (fd)
}
count = read(fd, buffer, max_size);
cout << "read" << count <<" bytes from file\n;
close(fd);
return 0;

write()
int getline(int fd, char * buffer, int max_size)
int fd, count;
char buffer[] =
fd = open(" ", O_WRONLY);
if (fd == -1) {
cerr << fild could not be opened\n";
exit (fd);
}
count = write(fd, buffer, sizeof(buffer));
cout << "wrote " << count <<" bytes to file\n";
close(fd);
return 0;

)

4. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course)
niu, dekalb, Il, ege, 330
).