Files.html (2829B)
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3 <html><head><link rel="stylesheet" href="sitewide.css"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><meta name="exporter-version" content="Evernote Mac 7.6 (457297)"/><meta name="altitude" content="-4.349451065063477"/><meta name="author" content="Alex Balgavy"/><meta name="created" content="2018-12-19 00:02:33 +0000"/><meta name="latitude" content="52.30032348632812"/><meta name="longitude" content="4.98812990790774"/><meta name="source" content="desktop.mac"/><meta name="updated" content="2018-12-19 00:02:57 +0000"/><title>Files</title></head><body><div>abstract storage 'devices' organised in (typically hierarchical) file system structure</div><div><br/></div><div>file access: 4 </div><ul><li><div>sequential (in order) vs. random access (e.g. second, then first, then third block)</div></li></ul><div>file types: 5 </div><ul><li><div>regular files, dirs, soft links</div></li><li><div>special files (e.g. device files, metadata files)</div></li></ul><div>file structure: 6 </div><ul><li><div>OS' perspective: files as streams of bytes</div></li><li><div>program's perspective: archives, executables, etc.</div></li><li><div>is OS ever aware of the file structure?</div></li></ul><div>file naming: 7 </div><ul><li><div>different file systems have different limitations/conventions for filenames</div></li><li><div>file extensions</div></li><li><div>file name length: 8 </div></li><ul><li><div>FAT: 8.3 characters (8 name, 3 extension. later extended to 255)</div></li><li><div>EXT4: 255 characters</div></li></ul><li><div>Special chars in filenames: 9 </div></li><ul><li><div>FAT: no "*/:<>?\| etc.</div></li><li><div>EXT4: no '\0' and '/' or special names '.' and '..'</div></li></ul><li><div>case sensitivity depends</div></li></ul><div>file attributes: 10 </div><ul><li><div>there's a whole bunch of them</div></li></ul><div><img src="Files.resources/C8443068-DC83-472E-B42F-1AEDC7CDD460.png" height="454" width="471"/></div><div>file operations: 11 </div><ul><li><div>create/delete</div></li><li><div>open/close</div></li><li><div>read/write</div></li><li><div>append</div></li><li><div>seek</div></li><li><div>get attributes/set attributes</div></li><li><div>rename</div></li></ul><div><br/></div><div>directories: 12 </div><ul><li><div>persistent data structures organising and maintaining info about files</div></li><li><div>file attrs stored in-band or out-of-band (both commonly used)</div></li></ul><div><img src="Files.resources/FD883BA4-6FD1-4ECC-B909-761D3A37B214.png" height="222" width="555"/></div><div><img src="Files.resources/350FD665-B09B-4CFA-B09B-0B3B02E7D9E0.png" height="324" width="691"/></div><div><br/></div></body></html>