IT 207 - Nodejs Synchronous File Systems APIs

What is a filesystem

major component of any operating system

What is a filesystem responsible for?

Persistently storing, managing, and updating data on a storage device

File systems 2 abstractions

Files and directories

Files

The smallest unit of persistent data storage

File

linear array of bytes, each of which can be read or written

How are files identified?

A textual name with 2 parts separated by a dot: unique file name and file type extension

File properties

File size (bytes), file creation date, file access date, default application for file, and access permissions stating who can read, write, and execute file

What is a Directory?

a container for files

How are directories organized?

Hierarchal structure such as a tree

How are directories identified?

textual name and low-level name

What is a path?

The sequence of directory names that starts from the root directory and specifies subsequent directories until the desired file is reached

How does a path separate directory names?

special characters

What does ./ refer to?

The current directory

What does ../ refer to?

The parent directory

cat

print file content

cp

copy file

mkdir

make directory

ls

list files and directories

rm

remove file

rmdir

remove directory

pwd

print working directory

mv

move file

touch

create, change, and modify timestamps of a file

Node Buffer

special objects that handle binary data and are used to represent a fixed-length of bytes

What scope is buffer class available within?

global scope

Functions that work on buffers

alloc()
toString()
write()
length

alloc()

Creates a buffer object of a specified length

toString()

Returns the string version of a buffer object

write()

Writes a specified string to a buffer object

length

Returns the length of a buffer object in bytes

built-in modules

path and fs

path

provides utilities for working with file and directory paths

fs

enables interacting with the fie system in a way modeled on standard POSIX functions

Environment variables

_filename, _dirname

_filename

holds the absolute file name of the current module

_dirname

holds the directory name of the current module

What 3 categories does Nodejs fs module provide for accessing files?

Synchronous APIs, Callback APIs, and Promise APIs

Which are Asynchronous APIs?

Callback APIs and Promise APIs

All synchronous functions will have the term ____ added to their name

Sync

Creating a directory in JS

fs.mkdirSync(path[, options])

Read the contents of a directory

fs.readdirSync(path[, options])

remove a directory

fs.rmdirSync (path[, options])

File reading functions

readFileSync(path[, options])

readSync(fd, buffer, offset, length[, position])

readSync(fd, buffer[, options])

Reading the status of a file function

statsSync(path[, options])

Writing to a file functions

writeFileSync(file, data[, options])

writeSync(fd, buffer, offset[, length[, position]])

writeSync(fd, buffer[, options])

writeSync(fd, string[, position[, encoding]])

appendFileSync(path, data[, options])

You cannot remove a folder with files, only ones that are empty

True

Nodejs provides the ____ object which has information about, and control over, the current Nodejs process

process.argv

process.argv

holds the command line arguments passed to the Nodejs process when it is launched