TRUNCATE(2)               OpenBSD Programmer's Manual              TRUNCATE(2)

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



SYNOPSIS
     #include <unistd.h>

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

     int
     ftruncate(int fd, off_t length);

DESCRIPTION
     truncate() causes the file named by path or referenced by fd to be trun-
     cated to at most length bytes in size.  If the file previously was larger
     than this size, the extra data is lost.  With ftruncate(), the file must
     be open for writing.

RETURN VALUES
     A value of 0 is returned if the call succeeds.  If the call fails a -1 is
     returned, and the global variable errno specifies the error.

ERRORS
     truncate() succeeds unless:

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

     [ENAMETOOLONG]
                   A component of a pathname exceeded {NAME_MAX} characters,
                   or an entire path name exceeded {PATH_MAX} 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 be-
                   ing executed.

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

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

     [EPERM]       The effective user ID does not match the owner of the file
                   and the effective user ID is not the super-user.

     ftruncate() succeeds unless:

     [EBADF]       The fd is not a valid descriptor.

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

     [EINVAL]      The fd is not open for writing.

SEE ALSO
     open(2)

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

HISTORY
     The truncate() and ftruncate() function calls appeared in 4.2BSD.

OpenBSD 2.6                      June 4, 1993                                2