Videos: File Descriptors

File descriptors are the main abstraction for interprocess communication in Unix.

• File Descriptor 1: Overview   2:06

  An introduction to the Unix view of files, including a file descriptor as a handle to an open file.

  At various points in this video, I say that /proc/cpuinfo is “not a file in the filesystem.” I mean to say that it’s “not a file that is stored on disk.” Even though the content of /proc/cpuinfo is generated on demand, it’s more precisely correct to say that it’s a file in the filesystem — everything is a file! — and just not on disk.

• File Descriptors 2: Example of reading a file   3:13
  An example of using the system-call API to real a file.

• File Descriptors 3: Pipes   2:36
  An introduction and example of Unix pipes.

• File Descriptors 4: Pipes and EOF   5:39
  Reading an EOF from a pipe and the importance of closing all write ends of a pipe.

• File Descriptors 5: Pipes and write blocking   2:16
  How a pipe’s buffer size implies that writes to a pipe must sometimes wait on reads.

• FIle Descriptors 6: Standard input, output, and error   2:45
  File descriptors 0, 1, and 2 as standard input, output, and error file descriptors.

• File Descriptors 7: Redirecting via dup2   3:50
  Using dup2 to change a standard file descriptor for a child process to redirect the child’s output.

• File Descriptors 8: Constructing pipelines   2:39
  How a shell creates pipes to chain a sequence of commands in a pipeline.

• File Descriptors 9: Unix vs. Standard C   5:54
  We have two libraries available for I/O: the Unix syscall API and the Standard C library. We compare the two libraries and investigate a key performance difference.

• File Descriptors 10: Output buffer modes   4:40
  Listing options for the buffering mode of a Standard C output file, including a discussion of the way a default mode is selected.