Warning: disk does not exist, initialized to blank
file foo created
file foo opened, index=1
60 bytes written
10 bytes written
current position is 55
10 bytes read: xxxxxyyyyy
file 1 closed
files: foo 70 

Warning: disk does not exist, initialized to blank
error: file foo does not exist
program terminated

/* NOTE: Your file system program should produce a single line of
output for each command in the input file. The output should state
which command has just been executed and include the following
information:  
-- for the open command, give the index assigned; 
-- for read/write, give the number of bytes read/written; 
-- for read, display the corresponding data just read;
-- for directory, display all file names and lengths;  */