Add a few Linux commands

src/linux.md

@@ -62,6 +62,9 @@ df -h
 
 # Count number of files and folders in home directory.
 ls ~ | wc -l
+
+# List block devices. Helps with seeing partition information.
+sudo lsblk -f -m
 ```
 
 ### Navigation
@@ -195,6 +198,13 @@ cat /etc/passwd
 
 # List all users across multiple sources.
 getent passwd
+
+# Install sudo on Debian or the like (that don't have it by default).
+apt update
+apt install sudo
+
+# Grant a user sudo.
+usermod -aG sudo <username>
 ```
 
 ## Permissions