truncate(2)truncate(2)Name
truncate, ftruncate - truncate a file to a specified length
Syntax
truncate(path, length)
char *path;
int length;
ftruncate(fd, length)
int fd, length;
Description
The system call causes the file named by path or referenced by fd to be
truncated to, at most, length bytes in size. If the file previously
was larger than this size, the extra data is lost. With the file must
be open for writing.
Return Values
A value of zero (0) is returned if the call succeeds. If the call
fails, a -1 is returned, and the global variable errno specifies the
error.
Restrictions
Partial blocks discarded as the result of truncation are not zero-
filled. This can result in holes in files that do not read as zero.
Diagnostics
The system call succeeds unless:
[ENOTDIR] A component of the path prefix is not a directory.
[ENOENT] The named file does not exist.
[EACCES] Search permission is denied for a component of the path
prefix.
[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.
[EFAULT] The path points outside the process's allocated address
space.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an
entire path name exceeded 1023 characters.
[ELOOP] Too many symbolic links were encountered in translating
the pathname.
[EIO] An I/O error occurred updating the inode.
The system call succeeds unless:
[EBADF] The fd is not a valid descriptor.
[EINVAL] The fd references a socket, not a file.
[ETIMEDOUT] A connect request or remote file operation failed,
because the connected party did not properly respond
after a period of time that is dependent on the communi‐
cations protocol.
See Alsoopen(2)truncate(2)
