bypass cache

Author: Hussein Nasser

14-file-io/144-file-bypasscache.js

@@ -0,0 +1,41 @@
+const fs = require("fs");
+const p = '/Users/HusseinNasser/Desktop/udemy/os-course/Edited/01-Welcome.mp4'
+const fd = fs.openSync(p, 'rs+')//by pass file system cache
+console.log("file descriptor " + fd)
+fs.closeSync(fd);
+
+/*
+The following flags are available wherever the flag option takes a string.
+
+'a': Open file for appending. The file is created if it does not exist.
+
+'ax': Like 'a' but fails if the path exists.
+
+'a+': Open file for reading and appending. The file is created if it does not exist.
+
+'ax+': Like 'a+' but fails if the path exists.
+
+'as': Open file for appending in synchronous mode. The file is created if it does not exist.
+
+'as+': Open file for reading and appending in synchronous mode. The file is created if it does not exist.
+
+'r': Open file for reading. An exception occurs if the file does not exist.
+
+'rs': Open file for reading in synchronous mode. An exception occurs if the file does not exist.
+
+'r+': Open file for reading and writing. An exception occurs if the file does not exist.
+
+'rs+': Open file for reading and writing in synchronous mode. Instructs the operating system to bypass the local file system cache.
+
+This is primarily useful for opening files on NFS mounts as it allows skipping the potentially stale local cache. It has a very real impact on I/O performance so using this flag is not recommended unless it is needed.
+
+This doesn't turn fs.open() or fsPromises.open() into a synchronous blocking call. If synchronous operation is desired, something like fs.openSync() should be used.
+
+'w': Open file for writing. The file is created (if it does not exist) or truncated (if it exists).
+
+'wx': Like 'w' but fails if the path exists.
+
+'w+': Open file for reading and writing. The file is created (if it does not exist) or truncated (if it exists).
+
+'wx+': Like 'w+' but fails if the path exists.
+*/