Birmingham mumbai

[
 158 
]
Next, let's make sure 
rsync
 is actually installed, and install it if it's not:
If [ ! -f /usr/bin/rsync ]; then 
    sudo apt install -y rsync 
fi 
Here, we're simply checking to see whether 
rsync
 is 
not
 installed. If it's not, we'll 
install it via 
apt
. This is similar to how we checked for the existence of 
apache2
 earlier 
in this chapter.
Now, we add the final line:
rsync -avb --delete --backup-dir=/backup/incremental/$CURDATE /src /
target
You can definitely see the magic of variables in Bash now, if you haven't already. 
We're including 
$CURDATE
 in our command, which is set to whatever the current date 
actually is. When we add it all together, our script looks like this:
#/bin/bash
CURDATE=$(date +%m-%d-%Y)
if [ ! -f /usr/bin/rsync ]; then 
    sudo apt install -y rsync 
fi
rsync -avb --delete --backup-dir=/backup/incremental/$CURDATE /src /
target 
This script, when run, will run an 
rsync
 job that will copy the contents from 
/src
 
to 
/target
. (Be sure to change these directories to match the source directory you 
want to back up and the target where you want to copy it to.) The beauty of this is 
that 
/target
 can be an external hard drive or network share. So, in a nutshell, you 
can automate a nightly backup. This backup, since we used the 
-b
 option along with 
--backup-dir
, will allow you to retrieve previous versions of a file from the 
/backup/
incremental
 directory. Feel free to get creative here as far as where to place previous 
file versions and where to send the backup.
Of course, don't forget to mark the script as executable, assuming it was saved with a 
name like 
backup.sh
:
chmod +x backup.sh

---

Chapter 6