unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (v7man)
Page:
Section:
Apropos / Subsearch:
optional field

READ(2)                       System Calls Manual                      READ(2)



NAME
       read - read from file

SYNOPSIS
       read(fildes, buffer, nbytes)
       char *buffer;

DESCRIPTION
       A  file  descriptor  is  a word returned from a successful open, creat,
       dup, or pipe call.  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 example if the file refers  to  a  type-
       writer  at  most one line will be returned.  In any event the number of
       characters read is returned.

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

SEE ALSO
       open(2), creat(2), dup(2), pipe(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.

ASSEMBLER
       (read = 3.)
       (file descriptor in r0)
       sys read; buffer; nbytes
       (byte count in r0)



                                                                       READ(2)