If your Ubuntu system disk is almost full, you can use the following methods to identify large files taking up space:
Check disk usage using the df command: Enter df -h in the terminal to view the disk usage of all partitions.
Find large files using the du command: Enter du -sh * in the terminal to see the sizes of all files in the current directory. This command can help you identify the largest files taking up space.
Use the ncdu tool: ncdu is a graphical tool for viewing disk usage. You can install it using the apt-get command: sudo apt-get install ncdu. Once installed, enter ncdu in the terminal and press Enter to use this tool to check disk usage.
You can choose one or more of the above methods according to your needs to identify large files taking up space.
Note: When using the du command, you need to first navigate to the directory you want to search in before using this command.