permstat.c takes an existing regular file, reads the permissions of the file in octal format, and returns the permission string in character form.
Only one file can be provided as an argument. If there is not exactly two argument, a usage statement will be printed.
permstat uses the stat command to obtain information about that file. If stat returns a value less than 0, an error will be printed out.
After obtaining the file's information, it check if the file is a regular file. Otherwise, an error will be printed.
The permission_string function takes the permission strings in octal form and uses permission macros (e.g.: S_IRUSR = User read permission macro). If the file has that permission, either a 'r','w', or 'x' will be added to the string. Otherwise, there will be a '-', meaning the file does not grant a certain permission for either the user, group, or other. Afterwards, the permission string will be printed.
