TRUNCATE(2)
NAME
truncate − truncate a file to a specified length
USAGE
truncate(path, length)
char *path;
int length;
ftruncate(fd, length)
int fd, length;
DESCRIPTION
Truncate truncates the file named by path or referred to by fd to a maximum of length bytes in size. If the file was larger than length, the extra data is lost. With ftruncate, the file must be open for writing.
NOTES
Partial blocks discarded as the result of truncation are not zero-filled; this can leave holes in files which do not read as zero.
RETURN VALUE
A value of zero is returned if the call succeeds. If the call fails, −1 is returned, and the global variable errno specifies the error.
ERRORS
Truncate succeeds unless:
[EPERM] The pathname contains a character with the high-order bit set.
[ENOENT] The pathname is too long.
[ENOTDIR] A component of the path prefix of path is not a directory.
[ENOENT] The named file does not exist.
[EACCES] A component of the path prefix denies search permission.
[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 (i.e., shared text) file that is being executed.
[EFAULT] Name points outside the process’ allocated address space.
Ftruncate succeeds unless:
[EBADF] The fd is not a valid descriptor.
[EINVAL] The fd refers to a socket, not a file.