# File The xv6 file system provides data files, which are uninterpreted byte arrays, and directories, which contain named references to data files and other directories. Paths that don’t begin with / are evaluated relative to the calling process’s current directory, A file, called an `inode`, can have multiple names, called `links`. The `link` system call creates another file system name referring to the same `inode` as an existing file. The file’s `inode` and the disk space holding its content are only **freed** when the **file’s link count is zero and no file descriptors refer to it.** `cd` changes current process working directory. When shell running this cmd, it does not fork child and change dir. Instead, it change the current working directory of the shell itself. The reason behind is: if forking a child to do `cd`, we are changing the child process’s working directory, not our current shell process. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://xiayingp.gitbook.io/build_a_os/os-interfaces/file.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.