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  man pages->FreeBSD man pages -> ftruncate (2)              



NAME    [Toc]    [Back]

     truncate, ftruncate -- truncate or extend a file to a specified length

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #include <unistd.h>

     truncate(const char *path, off_t length);

     ftruncate(int fd, off_t length);

DESCRIPTION    [Toc]    [Back]

     The truncate() system call causes the file named by path or referenced by
     fd to be truncated or extended to length bytes in size.  If the file was
     larger than this size, the extra data is lost.  If the file was smaller
     than this size, it will be extended as if by writing bytes with the value
     zero.  With ftruncate(), the file must be open for writing.

RETURN VALUES    [Toc]    [Back]

     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the

ERRORS    [Toc]    [Back]

     The truncate() system call succeeds unless:

     [ENOTDIR]		A component of the path prefix is not a directory.

     [ENAMETOOLONG]	A component of a pathname exceeded 255 characters, or
			an entire path name exceeded 1023 characters.

     [ENOENT]		The named file does not exist.

     [EACCES]		Search permission is denied for a component of the
			path prefix.

     [EACCES]		The named file is not writable by the user.

     [ELOOP]		Too many symbolic links were encountered in translating
 the pathname.

     [EISDIR]		The named file is a directory.

     [EROFS]		The named file resides on a read-only file system.

     [ETXTBSY]		The file is a pure procedure (shared text) file that
			is being executed.

     [EIO]		An I/O error occurred updating the inode.

     [EFAULT]		The path argument points outside the process's allocated
 address space.

     The ftruncate() system call succeeds unless:

     [EBADF]		The fd argument is not a valid descriptor.

     [EINVAL]		The fd argument references a socket, not a file.

     [EINVAL]		The fd descriptor is not open for writing.

SEE ALSO    [Toc]    [Back]


BUGS    [Toc]    [Back]

     These calls should be generalized to allow ranges of bytes in a file to
     be discarded.

     Use of truncate() to extend a file is not portable.

HISTORY    [Toc]    [Back]

     The truncate() system call appeared in 4.2BSD.

FreeBSD 5.2.1			 June 4, 1993			 FreeBSD 5.2.1
[ Back ]
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