Challenge_04

1. If you create a file while using the linux terminal will the locate command be able to find it, right after it was created ? If not then what should 
   one do?
Sol. 
No.
touch pwd.txt
sudo updatedb
locate pwd.txt


2. Find all regular files in /var that have a size bigger than 2 MB and apply cat command on each of them.
Sol. 
sudo find /var/* -size +2M -exec cat{} \;


3. Create a backup of all the above files in a new directory.
Sol. 
mkdir Backup
sudo find /var/* -size +2M -exec cp {} Backup \;


4. From the files backed up above, delete the files which are not owned by the root user.
Sol.
sudo find /var -type f -not -user root -exec shred -vu -n 100 {} \;


5. List out the last 5 authentications which failed, in your system.
Sol. 
cat /var/log/auth.log | tail -n 5 | grep "authentication failure"


6. Print the total number of failed authentications that ever occured in your system.
Sol.
cat /var/log//auth.log | grep "authentication failure" | wc -l


7. Give an example of redirection of stdout and stderr both to a single text file.
Sol. 
tail -n 3 /etc/passwd /etc/shadow > output.txt 2>&1