WRITE (2)
write to a file descriptor
SYNOPSIS
#include <unistd.h>
ssize_t write(int fd , const void * buf , size_t count );
DESCRIPTION
write
writes up to
count
bytes to the file referenced by the file descriptor
fd
from the buffer starting at
buf.
POSIX requires that a read() which can be proved to occur after a
write() has returned returns the new data. Note that not all file
systems are POSIX conforming.
RETURN VALUE
On success, the number of bytes written are returned (zero indicates
nothing was written). On error, -1 is returned, and errno is set
appropriately. If count is zero and the file descriptor refers to
a regular file, 0 will be returned without causing any other effect.
For a special file, the results are not portable.
ERRORS
EBADF
fd
is not a valid file descriptor or is not open for writing.
EINVAL
fd
is attached to an object which is unsuitable for writing.
EFAULT
buf
is outside your accessible address space.
EPIPE
fd
is connected to a pipe or socket whose reading end is closed. When this
happens the writing process will receive a
SIGPIPE
signal; if it catches, blocks or ignores this the error
EPIPE
is returned.
EAGAIN
Non-blocking I/O has been selected using
O_NONBLOCK
and there was no room in the pipe or socket connected to
fd
to write the data immediately.
EINTR
The call was interrupted by a signal before any data was written.
ENOSPC
The device containing the file referred to by
fd
has no room for the data.
EIO
A low-level I/O error occurred while modifying the inode.
Other errors may occur, depending on the object connected to
fd .
CONFORMING TO
SVr4, SVID, POSIX, X/OPEN, 4.3BSD. SVr4 documents additional error
conditions EDEADLK, EFBIG, ENOLCK, ENOLNK, ENOSR, ENXIO, EPIPE, or ERANGE.
Under SVr4 a write may be interrupted and return EINTR at any point,
not just before any data is written.
SEE ALSO
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