truncate(3C)           UNIX System V(C Development Set)            truncate(3C)


NAME
      truncate, ftruncate - set a file to a specified length

SYNOPSIS
      #include <unistd.h>

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

      int ftruncate (int fildes, offt 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.

      truncate fails 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.

      EINTR             A signal was caught during execution of the truncate
                        routine.

      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.





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truncate(3C)           UNIX System V(C Development Set)            truncate(3C)


      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 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
                        routine.

      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.

SEE ALSO
      fcntl(2), open(2)

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







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