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<html>
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<body>
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<pre>
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NAME
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       read - read from a file descriptor
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SYNOPSIS
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       ssize_t read(int fd, void *buf, size_t count);
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DESCRIPTION
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       read()  attempts  to  read  up  to  count  bytes from file
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       descriptor fd into the buffer starting at buf.
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       If count is zero, read() returns zero  and  has  no  other
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       results.
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RETURN VALUE
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       On success, the number of bytes  read  is  returned  (zero
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       indicates  end of file), and the file position is advanced
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       by this number.  It is not an  error  if  this  number  is
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       smaller  than the number of bytes requested; this may hap-
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       pen for example because fewer bytes are actually available
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       right  now (maybe because we were close to end-of-file, or
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       because we are reading from a pipe, or from  a  terminal),
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       or  because read() was interrupted by a signal.  On error,
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       -1 is returned, and errno is set  appropriately.  In  this
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       case  it is left unspecified whether the file position (if
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       any) changes.
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ERRORS
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       EINTR   The call was interrupted by a  signal  before  any
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               data was read.
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       EAGAIN  Non-blocking  I/O  has  been selected using O_NON-
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               BLOCK and no data was  immediately  available  for
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               reading.
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       EIO     I/O  error.  This will happen for example when the
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               process is in a background process group, tries to
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               read  from  its  controlling tty, and either it is
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               ignoring or blocking SIGTTIN or its process  group
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               is  orphaned.   It  may also occur when there is a
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               low-level I/O error while reading from a  disk  or
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               tape.
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       EISDIR  fd refers to a directory.
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       EBADF   fd  is  not a valid file descriptor or is not open
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               for reading.
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       EINVAL  fd is attached to an object  which  is  unsuitable
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               for reading.
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       Other  errors may occur, depending on the object connected
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       to fd.  POSIX allows a  read  that  is  interrupted  after
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       reading  some  data to return -1 (with errno set to EINTR)
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       or to return the number of bytes already read.
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</pre>
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</body>
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</html>

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