Description
- (a) Extend code snippet 1 to check for read and write access permissions of a given file
(b) Write a C program where open system call creates a new file (say, destination.txt ) and then opens it. (Hint: use the bitwise OR flag)
- UNIX cat command has three functions with regard to text files: displaying them, combining copies of them and creating new ones.
Write a C program to implement a command called printcontent that takes a (text) file name as argument and displays its contents. Report an appropriate message if the file does not exist or can’t be opened (i.e. the file doesn’t have read permission). You are to use open() , read() , write() and close() system calls.
- The cp command copies the source file specified by the SourceFile parameter to the destination file specified by the DestinationFile parameter.
Write a C program that mimics the cp command using open() system call to open source.txt file in read-only mode and copy the contents of it to destination.txt using read() and write() system calls.
- Repeat part 2 (by writing a new C program) as per the following procedure:
- Read the next 50 characters from txt , and among characters read, replace each char- acter ’5’ with character ‘A’’ and all characters are then written in destination.txt
- Write characters “XYZ” into file txt
( c) Repeat the previous steps until the end of file source.txt . The last read step may not have 50 characters.
General Instructions:
Use perror subroutine to display meaningful error messages in case of system call failures.
Properly close the files using close system call after you finish read/write. Learn to use man pages to know more about file management system calls (e.g, man read ).
