Lab 04

Part 1: Standard Output Redirection

Tasks

• Redirect the output of the ls command to a file named files_list.txt
• Display the contents of the numbers.txt file using the cat command, and redirect the output to a file named numbers_copy.txt
• Use the echo command to add a new line with the text "This is a new line" to the end of numbers_copy.txt file using the append operator
• Use the ls command with the -la option and redirect its output to the file directory_info.txt
• Create a file named timestamp.txt containing the current date and time by redirecting the output of the date command

Part 2: Standard Error Redirection

Tasks

• Attempt to list a non-existent directory and redirect the error message to a file called errors.log
• Run a command to find all files with .txt extension in your home directory, redirecting any errors to a file named find_errors.log and the successful output to found_files.txt
• Create a file that combines both standard output and standard error from the grep command when searching for the pattern "ERROR" in server.log (redirect to all_output.log)
• Try to read a file that doesn't exist and redirect the error to /dev/null (effectively silencing the error)
• Run a command that generates both output and errors, saving the output to command_output.txt and the errors to command_errors.txt

Part 3: Pipes

Tasks

• Count the number of lines in the server.log file using a pipe with wc -l
• List only files with the .txt extension in the current directory using a pipe with grep
• Display a sorted list of unique fruits from the unsorted_data.txt file using pipes
• Find all lines in server.log containing the word "ERROR" and count them using pipes
• Extract only the username field (first column) from users.txt and sort it alphabetically using pipes
• Count how many users belong to each department using pipes with cut and sort and uniq -c
• Find the top 3 largest files in the current directory using pipes
• List all log entries from server.log between 10:00 and 12:00 using grep and pipes

Part 4: Here Documents

Tasks

• Create a new file called introduction.txt using a here document with at least 3 lines of text
• Use a here document with the grep command to search for multiple patterns in server.log
• Create a simple HTML file named simple.html using a here document
• Use a here document with the sed command to perform multiple substitutions on users.txt
• Execute multiple SQL-like commands using a here document (simulate with echo or another command)

Part 5: Here Strings

Tasks

• Use a here string to count the number of characters in the text "Linux is an open-source operating system"
• Search for the word "apple" in a here string containing a list of fruits
• Convert a string to uppercase using a here string with the tr command
• Use a here string to check if a specific IP address is present in the server.log file
• Sort the comma-separated values "3,1,4,1,5,9,2,6" using a here string

Part 6: Process Substitution

Tasks

• Compare the contents of dir1_files.txt and dir2_files.txt using diff with process substitution
• Sort both dir1_files.txt and dir2_files.txt and find common files using comm with process substitution
• Use paste with process substitution to combine the sorted contents of numbers.txt with the uppercase version of the same file
• Find the differences between the original unsorted_data.txt and a sorted version using process substitution
• Create a backup of users.txt where all instances of "company.com" are replaced with "newcompany.com" using process substitution

Part 7: Combining Techniques

Tasks

• Create a report showing all ERROR and WARNING entries from server.log, sorted by time
• Extract all unique email addresses from users.txt and save them to a file called emails.txt
• Count the occurrences of each log level ([INFO], [ERROR], [WARNING]) in server.log and create a summary
• Find files that exist in dir1_files.txt but not in dir2_files.txt and vice versa
• Process server.log to create a list of users who logged in, along with their login times