NAME

read − read input

SYNOPSIS

cc = read(d, buf, nbytes)
int cc, d;
char *buf;
int nbytes;

DESCRIPTION

Read attempts to read nbytes of data from the object referenced by the descriptor d into the buffer pointed to by buf.

On objects capable of seeking, the read starts at a position given by the pointer associated with d (see lseek(2)). Upon return from read, the pointer is incremented by the number of bytes actually read.

Objects that are not capable of seeking always read from the current position.  The value of the pointer associated with such an object is undefined. 

Upon successful completion, read returns the number of bytes actually read and placed in the buffer.  The system guarantees to read the number of bytes requested if the descriptor references a normal file that has that many bytes left before the end-of-file, but in no other case. 

If the returned value is 0, then end-of-file has been reached. 

RETURN VALUE

If successful, the number of bytes actually read is returned.  Otherwise, a −1 is returned and the global variable errno is set to indicate the error.