#!/usr/bin/env python3

# Reading and writing to files.

# 1. Use the `open` builtin to create a file handler

# `readlines` is used to read all the lines in the file.

# `readlines` returns a list.

# Make sure the file descriptor is closed after the operations.

try:

fd1 = open("/tmp/new.txt")

data = fd1.readlines()

print(data)

fd1.close()

except IOError:

print("IOError while reading {0}".format(fd1.name))

# 2. Modes of access

# `open()` takes multiple modes, ie. read, write, read_write etc.

# Refer `help(open)` for details.

"""

Character Meaning

--------- ---------------------------------------------------------------

'r' open for reading (default)

'w' open for writing, truncating the file first

'x' create a new file and open it for writing

'a' open for writing, appending to the end of the file if it exists

'b' binary mode

't' text mode (default)

'+' open a disk file for updating (reading and writing)

'U' universal newline mode (deprecated)

"""

try:

fd2 = open("/tmp/new.txt", "a")

fd2.write("Hello, I am testing writes!\n")

fd2.close()

except IOError:

print("IOError while reading {0}".format(fd2.name))

# 3. Read in various chunks

# Reads can be done as

# * One line at a time.

# * Read all lines in a single go (output as a list)

# * Read the file in chunks.