Birmingham mumbai

[
 114 
]
By default, 
grep
 is case-sensitive. This means that if we were to use 
grep
 to find lines 
matching "port" (with a lowercase P), we would get no output at all. We can simply 
add the 
-i
 argument to make the search case-insensitive.
It's very common to see the 
grep
 command paired with another command, such as 
cat
:
cat /etc/ssh/sshd_config | grep Port
That's a perfectly valid command, and will do the same thing. However, it's fairly 
redundant. We'll get into the concept of redirecting output in the next chapter, but 
essentially this command takes the output of the 
cat
 command and redirects it as 
input to the 
grep
 command. Using 
cat
 to first print out the file and then have 
grep
 
grab the contents of that file 
and search it for a string is a two-step process where 
only one step is required. But again, it's still a valid command. To this day, I'll 
personally use the 
cat
 command with 
grep
 to do the same thing out of habit, as this 
was how all new Linux users were taught back when I started. You'll even see me do 
this in my YouTube videos—old habits are hard to break!
Log files are a great source of information about what's going on in the background 
of your server, and are especially useful for troubleshooting. We'll now transition 
into a discussion on viewing these files and some relevant commands pertaining to 
logging.