READ(2) READ(2)
NAME
read - read from file
SYNOPSIS
read(fildes, buffer, nbytes)
char *buffer;
DESCRIPTION
Read causes data to be read from the open file associated
with the file descriptor. Buffer is the location of nbytes
contiguous bytes into which the input will be placed. It is
not guaranteed that all nbytes bytes will be read; for exam-
ple if the file refers to a terminal at most one line will
be returned. In any event the number of characters read is
returned.
A return value of 0 is conventionally interpreted as end of
file. If more data is subsequently written on the open file
by another process, then a further read will return it.
SEE ALSO
open(2), creat(2), dup(2), pipe(2), select(2)
DIAGNOSTICS
As mentioned, 0 is returned when the end of the file has
been reached. If the read was otherwise unsuccessful the
return value is -1. Many conditions can generate an error:
physical I/O errors, bad buffer address, preposterous
nbytes, file descriptor not that of an input file.