homework linux 3

🔍 `grep` Tasks

Search for the word Linux in file.txt.
Search case-insensitively for ubuntu.
Count how many lines contain error.
Show only the matching part using -o.
Show line numbers with matches.
Search recursively in a folder.
Invert match to find lines without hello.
Use regex to match lines starting with "A".
Match exact whole word root.
Combine with ps aux | grep ssh.

🗑️ `rm` Tasks

Delete a file temp.txt.
Delete multiple files rm a.txt b.txt.
Delete all .log files in a directory.
Use rm -i to confirm before deletion.
Delete a folder and its contents recursively.
Delete hidden files in current directory.
Delete files older than 2 days using find and rm.
Prevent rm from deleting a file with chattr +i.
Try rm -v to see what’s being removed.
Use rm -r on a test directory testdir/.

➡️ Redirection `>` Tasks

Write output of date to today.txt.
Redirect whoami to a file.
Overwrite test.txt with echo.
Redirect ls -l to a new file.
Redirect error from cat nofile to err.txt.
Redirect command output into /dev/null.
Save disk usage to disk.txt.
Run uptime and save output.
Redirect list of users from /etc/passwd.
Check if file was overwritten.

➕ Append `>>` Tasks

Append current time to log.txt.
Append uname -a to sysinfo.txt.
Add a new line to an existing file.
Save the result of multiple commands into one file.
Combine with echo to create a multiline file.
Append ping results to pinglog.txt.
Append errors of a failed command.
Add student names to a list file.
Append system uptime daily (cron job idea).
Log current directory to path.log.

📥📤 stdin, stdout, stderr Tasks

Use cat without file to enter text from stdin.
Redirect stdout of ls to out.txt.
Redirect stderr from cat wrong to error.txt.
Use 2>&1 to combine error and output.
Pipe stdin from echo to another command.
Write a command that reads from a file as stdin.
Filter only errors using 2> redirection.
Send output to screen and file using tee.
Use | to pass stdout as stdin to grep.
Demonstrate stdin with read in a script.

🔡 `sort` Tasks

Sort a list of names in a file.
Sort numbers in ascending order.
Sort with -r for reverse.
Sort and remove duplicates.
Sort by numeric value -n.
Sort by a specific column in a CSV file.
Sort ignoring case.
Sort file and save result.
Combine with uniq to show unique sorted lines.
Sort the result of ps aux.

🔁 `uniq` Tasks

Remove duplicate lines from names.txt.
Count unique lines using -c.
Show only repeated lines using -d.
Show only unique lines using -u.
Sort a file then apply uniq.
Chain with sort | uniq -c.
Show how many times each IP appears in access.log.
Detect duplicates in student list.
Use uniq on sorted numeric values.
Count unique error messages in a log file.

🔎 `find` Tasks

Find all .txt files.
Find files modified in last 1 day.
Find files bigger than 5MB.
Find empty files.
Find files with -name and delete them.
Find all hidden files.
Find files with 777 permissions.
Find files owned by a user.
Find and archive results.
Find directories only.

✂️ `cut` Tasks

Extract first column of a CSV.
Cut usernames from /etc/passwd.
Extract the second field by delimiter : from a file.
Cut first 10 characters from each line.
Extract filename from full path.
Combine with ls -l | cut to get file sizes.
Show domains from email list.
Cut and save result to cut.txt.
Extract year from date YYYY-MM-DD.
Use cut with df -h to display only used percent.

🧠 `awk` Tasks

Print the first column from /etc/passwd.
Print 1st and 3rd column from a CSV.
Sum all numbers in second column.
Print lines where second field > 100.
Count lines with more than 3 fields.
Replace "admin" with "user" in a file.
Format output: awk '{print "Name: "$1}'.
Calculate average from a column.
Use condition if in awk.
Chain grep | awk to format filtered output.