Instructions Add a command to this chapter’s case study program that allows the user to view the contents of a file in the current working directory. When the command is selected, the program should display a list of filenames and a prompt for the name of the file to be viewed. Be sure to include error recovery in the program. If the user enters a filename that does not exist they should be prompted to enter a filename that does exist. An example of the program input and output is shown below: /root/sandbox 1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 7 View the contents of a file 8 Quit the program Enter a number: 7 Files in /root/sandbox: filesys.py example.txt Enter a file name from these names: example.txt THIS IS CONTENT OF AN EXAMPLE FILE. /root/sandbox 1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 7 View the contents of a file 8 Quit the program Enter a number: 8 Have a nice day! """ File: filesys.py Project 6.6 Provides a menu-driven tool for navigating a file system and gathering information on files. Adds a command to view a file's contents. """ import os, os.path QUIT = '8' COMMANDS = ('1', '2', '3', '4', '5', '6', '8') MENU = """1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 8 Quit the program""" def main(): while True: print(os.getcwd()) print(MENU) command = acceptCommand() runCommand(command) if command == QUIT: print("Have a nice day!") break def acceptCommand(): """Inputs and returns a legitimate command number.""" while True: command = input("Enter a number: ") if not command in COMMANDS: print("Error: command not recognized") else: return command def runCommand(command): """Selects and runs a command.""" if command == '1': listCurrentDir(os.getcwd()) elif command == '2': moveUp() elif command == '3': moveDown(os.getcwd()) elif command == '4': print("The total number of files is", \ countFiles(os.getcwd())) elif command == '5': print("The total number of bytes is", \ countBytes(os.getcwd())) elif command == '6': target = input("Enter the search string: ") fileList = findFiles(target, os.getcwd()) if not fileList: print("String not found") else: for f in fileList: print(f) # add your condition here elif command == '8': print("Files in", os.getcwd()) print(listCurrentDir(os.getcwd())) viewFile = input("Enter a file name from these names: ") viewFile() def viewFile(dirName): # write your code here f = open("viewFile", "r") print(f.read) print("") def listCurrentDir(dirName): """Prints a list of the cwd's contents.""" lyst = os.listdir(dirName) for element in lyst: print(element) def moveUp(): """Moves up to the parent directory.""" os.chdir("..") def moveDown(currentDir): """Moves down to the named subdirectory if it exists.""" newDir = input("Enter the directory name: ") if os.path.exists(currentDir + os.sep + newDir) and \ os.path.isdir(newDir): os.chdir(newDir) else: print("ERROR: no such name") def countFiles(path): """Returns the number of files in the cwd and all its subdirectories.""" count = 0 lyst = os.listdir(path) for element in lyst: if os.path.isfile(element): count += 1 else: os.chdir(element) count += countFiles(os.getcwd()) os.chdir("..") return count def countBytes(path): """Returns the number of bytes in the cwd and all its subdirectories.""" count = 0 lyst = os.listdir(path) for element in lyst: if os.path.isfile(element): count += os.path.getsize(element) else: os.chdir(element) count += countBytes(os.getcwd()) os.chdir("..") return count def findFiles(target, path): """Returns a list of the file names that contain the target string in the cwd and all its subdirectories.""" files = [] lyst = os.listdir(path) for element in lyst: if os.path.isfile(element): if target in element: files.append(path + os.sep + element) else: os.chdir(element) files.extend(findFiles(target, os.getcwd())) os.chdir("..") return files if __name__ == "__main__": main()

Instructions Add a command to this chapter’s case study program that allows the user to view the contents of a file in the current working directory. When the command is selected, the program should display a list of filenames and a prompt for the name of the file to be viewed. Be sure to include error recovery in the program. If the user enters a filename that does not exist they should be prompted to enter a filename that does exist. An example of the program input and output is shown below: /root/sandbox 1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 7 View the contents of a file 8 Quit the program Enter a number: 7 Files in /root/sandbox: filesys.py example.txt Enter a file name from these names: example.txt THIS IS CONTENT OF AN EXAMPLE FILE. /root/sandbox 1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 7 View the contents of a file 8 Quit the program Enter a number: 8 Have a nice day! """ File: filesys.py Project 6.6 Provides a menu-driven tool for navigating a file system and gathering information on files. Adds a command to view a file's contents. """ import os, os.path QUIT = '8' COMMANDS = ('1', '2', '3', '4', '5', '6', '8') MENU = """1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 8 Quit the program""" def main(): while True: print(os.getcwd()) print(MENU) command = acceptCommand() runCommand(command) if command == QUIT: print("Have a nice day!") break def acceptCommand(): """Inputs and returns a legitimate command number.""" while True: command = input("Enter a number: ") if not command in COMMANDS: print("Error: command not recognized") else: return command def runCommand(command): """Selects and runs a command.""" if command == '1': listCurrentDir(os.getcwd()) elif command == '2': moveUp() elif command == '3': moveDown(os.getcwd()) elif command == '4': print("The total number of files is", \ countFiles(os.getcwd())) elif command == '5': print("The total number of bytes is", \ countBytes(os.getcwd())) elif command == '6': target = input("Enter the search string: ") fileList = findFiles(target, os.getcwd()) if not fileList: print("String not found") else: for f in fileList: print(f) # add your condition here elif command == '8': print("Files in", os.getcwd()) print(listCurrentDir(os.getcwd())) viewFile = input("Enter a file name from these names: ") viewFile() def viewFile(dirName): # write your code here f = open("viewFile", "r") print(f.read) print("") def listCurrentDir(dirName): """Prints a list of the cwd's contents.""" lyst = os.listdir(dirName) for element in lyst: print(element) def moveUp(): """Moves up to the parent directory.""" os.chdir("..") def moveDown(currentDir): """Moves down to the named subdirectory if it exists.""" newDir = input("Enter the directory name: ") if os.path.exists(currentDir + os.sep + newDir) and \ os.path.isdir(newDir): os.chdir(newDir) else: print("ERROR: no such name") def countFiles(path): """Returns the number of files in the cwd and all its subdirectories.""" count = 0 lyst = os.listdir(path) for element in lyst: if os.path.isfile(element): count += 1 else: os.chdir(element) count += countFiles(os.getcwd()) os.chdir("..") return count def countBytes(path): """Returns the number of bytes in the cwd and all its subdirectories.""" count = 0 lyst = os.listdir(path) for element in lyst: if os.path.isfile(element): count += os.path.getsize(element) else: os.chdir(element) count += countBytes(os.getcwd()) os.chdir("..") return count def findFiles(target, path): """Returns a list of the file names that contain the target string in the cwd and all its subdirectories.""" files = [] lyst = os.listdir(path) for element in lyst: if os.path.isfile(element): if target in element: files.append(path + os.sep + element) else: os.chdir(element) files.extend(findFiles(target, os.getcwd())) os.chdir("..") return files if name == "main": main()

Programming Logic & Design Comprehensive

9th Edition

ISBN:9781337669405

Author:FARRELL

Publisher:FARRELL

Chapter7: File Handling And Applications

Section: Chapter Questions

Problem 7RQ

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Question

Instructions

Add a command to this chapter’s case study program that allows the user to view the contents of a file in the current working directory. When the command is selected, the program should display a list of filenames and a prompt for the name of the file to be viewed.

Be sure to include error recovery in the program. If the user enters a filename that does not exist they should be prompted to enter a filename that does exist.

An example of the program input and output is shown below:

/root/sandbox 1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 7 View the contents of a file 8 Quit the program Enter a number: 7 Files in /root/sandbox: filesys.py example.txt Enter a file name from these names: example.txt THIS IS CONTENT OF AN EXAMPLE FILE. /root/sandbox 1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 7 View the contents of a file 8 Quit the program Enter a number: 8 Have a nice day!

"""

File: filesys.py

Project 6.6

Provides a menu-driven tool for navigating a file system

and gathering information on files.

Adds a command to view a file's contents.

"""

import os, os.path

QUIT = '8'

COMMANDS = ('1', '2', '3', '4', '5', '6', '8')

MENU = """1 List the current directory

2 Move up

3 Move down

4 Number of files in the directory

5 Size of the directory in bytes

6 Search for a file name

8 Quit the program"""

def main():

while True:

print(os.getcwd())

print(MENU)

command = acceptCommand()

runCommand(command)

if command == QUIT:

print("Have a nice day!")

break

def acceptCommand():

"""Inputs and returns a legitimate command number."""

while True:

command = input("Enter a number: ")

if not command in COMMANDS:

print("Error: command not recognized")

else:

return command

def runCommand(command):

"""Selects and runs a command."""

if command == '1':

listCurrentDir(os.getcwd())

elif command == '2':

moveUp()

elif command == '3':

moveDown(os.getcwd())

elif command == '4':

print("The total number of files is", \

countFiles(os.getcwd()))

elif command == '5':

print("The total number of bytes is", \

countBytes(os.getcwd()))

elif command == '6':

target = input("Enter the search string: ")

fileList = findFiles(target, os.getcwd())

if not fileList:

print("String not found")

else:

for f in fileList:

print(f)

# add your condition here

elif command == '8':

print("Files in", os.getcwd())

print(listCurrentDir(os.getcwd()))

viewFile = input("Enter a file name from these names: ")

viewFile()

def viewFile(dirName):

# write your code here

f = open("viewFile", "r")

print(f.read)

print("")

def listCurrentDir(dirName):

"""Prints a list of the cwd's contents."""

lyst = os.listdir(dirName)

for element in lyst: print(element)

def moveUp():

"""Moves up to the parent directory."""

os.chdir("..")

def moveDown(currentDir):

"""Moves down to the named subdirectory if it exists."""

newDir = input("Enter the directory name: ")

if os.path.exists(currentDir + os.sep + newDir) and \

os.path.isdir(newDir):

os.chdir(newDir)

else:

print("ERROR: no such name")

def countFiles(path):

"""Returns the number of files in the cwd and

all its subdirectories."""

count = 0

lyst = os.listdir(path)

for element in lyst:

if os.path.isfile(element):

count += 1

else:

os.chdir(element)

count += countFiles(os.getcwd())

os.chdir("..")

return count

def countBytes(path):

"""Returns the number of bytes in the cwd and

all its subdirectories."""

count = 0

lyst = os.listdir(path)

for element in lyst:

if os.path.isfile(element):

count += os.path.getsize(element)

else:

os.chdir(element)

count += countBytes(os.getcwd())

os.chdir("..")

return count

def findFiles(target, path):

"""Returns a list of the file names that contain

the target string in the cwd and all its subdirectories."""

files = []

lyst = os.listdir(path)

for element in lyst:

if os.path.isfile(element):

if target in element:

files.append(path + os.sep + element)

else:

os.chdir(element)

files.extend(findFiles(target, os.getcwd()))

os.chdir("..")

return files

if __name__ == "__main__":

main()

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