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truncate(2)


truncate, truncate64, ftruncate, ftruncate64 -- set a file to a specified length

Synopsis

   #include <unistd.h>
   

int truncate (const char *path, off_t length);

int truncate64 (const char *path, off64_t length);

int ftruncate (int fildes, off_t length);

int ftruncate64 (int fildes, off64_t length);

Description

The file whose name is given by path or referenced by the descriptor fildes has its size set to length bytes.

If the file was previously longer than length, bytes past length will no longer be accessible. If it was shorter, bytes from the EOF before the call to the EOF after the call will be read in as zeros. The effective user ID of the process must have write permission for the file, and for ftruncate the file must be open for writing.

Return values

Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

truncate and truncate64 fail if one or more of the following are true:


EACCES
Search permission is denied on a component of the path prefix.

EACCES
Write permission is denied for the file referred to by path.

EFAULT
path points outside the process's allocated address space.

EFBIG
An attempt is made to write a file that exceeds the process's file size limit or the maximum file size (see getrlimit(2) and ulimit(2)).

EINTR
A signal was caught during execution of the truncate or truncate64 routines.

EINVAL
path is not an ordinary file.

EIO
An I/O error occurred while reading from or writing to the file system.

EISDIR
The file referred to by path is a directory.

ELOOP
Too many symbolic links were encountered in translating path.

EMFILE
The maximum number of file descriptors available to the process has been reached.

EMULTIHOP
Components of path require hopping to multiple remote machines and file system type does not allow it.

ENAMETOOLONG
The length of a path component exceeds {NAME_MAX} characters, or the length of path exceeds {PATH_MAX} characters.

ENFILE
Could not allocate any more space for the system file table.

ENOENT
Either a component of the path prefix or the file referred to by path does not exist.

ENOLINK
path points to a remote machine and the link to that machine is no longer active.

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

EROFS
The file referred to by path resides on a read-only file system.

ETXTBSY
The file referred to by path is a pure procedure (shared text) file that is being executed.

ftruncate fails if the following is true:


EFBIG
The file is a regular file and length is greater than the offset maximum established in the open file descriptor associated with fildes.

ftruncate and ftruncate64 fail if one or more of the following are true:


EAGAIN
The file exists, mandatory file/record locking is set, and there are outstanding record locks on the file (see chmod(2)).

EBADF
fildes is not a file descriptor open for writing.

EINTR
A signal was caught during execution of the ftruncate or ftruncate64 routines.

EIO
An I/O error occurred while reading from or writing to the file system.

ENOLINK
fildes points to a remote machine and the link to that machine is no longer active.

EINVAL
fildes does not correspond to an ordinary file.
In general, the system supports blocking truncates, as described in fcntl(2), which may result in EDEADLK being set.

References

fcntl(2), intro(2), open(2)

Notices

Considerations for large file support

truncate64 and ftruncate64 support large files, but are otherwise identical to truncate and ftruncate, respectively. For details on programming for large file capable applications, see ``Large File Support'' on intro(2).
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 25 April 2004