This program is designed to imitate the implementation of the cat command using various system calls like open(), close(), read(), write(). The program is completely written in C, and uses the default compiler for FreeBSD which uses the command cc to get compile.

• Clone or download this repository.
• Navigate to the directory and open it on terminal.
• Compile the source code using make.
• Now you have an executable with the name of mycat.
• You can remove the executable using make clean.

• open(): The open() system call opens the file specified by file name. and takes a second argument of flags.
• close(): The close() system call closes the file after finishing I/O operation
• read(): read() reads up to an x number of bytes from a certain file into the buffer. A buffer has to be created first.
• write(): write() writes up to an x number bytes from the buffer starting at a certain point to the file referred to in the function declaration.
• perror(): perror() prints a system error message.

• O_RDONLY: short for Read Only.

• ./mycat file1.txt file2.txt file3.txt: output from each file will be printed to standard output.
• ./mycat file100.txt: an error will be printed to standard output.
• ./mycat: Program will take input from the user and then the output will be printed to standard output.
• ./mycat < file1 > file2: Input will be read from file1 and written into file2.
• ./mycat file1 | grep string1: A line containing "string1" will be printed.

Assignment By: Ahmed SalahEldin Farouk Elkashef - 1410216.