HP C/iX Library Reference Manual (30026-90004)

Chapter 5 289
HP C/iX Library Function Descriptions
read
read
Reads input from a file.
Syntax
int read (int fildes , char * buffer , unsigned nbyte );
Parameters
fildes An open file descriptor.
buffer A pointer to a buffer where the function returns data.
nbyte The number of bytes to read and place in buffer .
Return Values
>0 Indicates success and the number of bytes read. This number may be less
than
nbyte if:
• The file is associated with a communication line.
• The number of bytes left in the file is less than
nbyte bytes.
EOF Returned when an end-of-file is reached.
−1 Indicates unsuccessful completion. The errno variable is set if one of the
following conditions is true:
EBADF The
fildes parameter is not a valid file descriptor open
for reading.
ESYSERR A call to a system intrinsic failed.
Description
The read function reads nbyte bytes from the file associated with fildes and places the
data read into the buffer pointed to by
buffer .
On devices capable of seeking, read() starts at a position in the file given by the file offset
associated with
fildes . Upon return from read(), the file pointer is incremented by the
number of bytes actually read.
Devices that are incapable of seeking always read from the current position. The value of a
file offset associated with such a device is undefined.
Unless an error occurs, a process blocks until a read() request is completed.
NOTE If linking with the POSIX/iX library, refer to the description of read() located
in the MPE/iX Developer's Kit Reference Manual.