Bsrgvty

Recently I faced similar situation. Too many applications got installed and they started using my root mount space. I am listing out few steps which I followed and hoping that you could also use the same.

1. 
   

   Clean apt-get cache. Following command will remove all downloaded deb files from apt-get cache directory.

   
   
   

   Run this command: sudo apt-get clean

   
   



2. Move /home mount point to different drive. Previously, my home folder was situated on root drive. So I moved my home folder to separate drive. This helped me to release lot of stress from root mount because most of applications store their data in /home/user_name/ folder. Read how to move home folder to separate drive.




3. Increase size of root partition I know it is very obvious answer. But believe me, our data need changes over the time. I thought 20 GB /root mount would suffice but withing a year I have re-sized my root mount and increased to 50 GB.

I successfully cleared 3.5 GB by removing old headers and images, using the following command:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/(.*)-([^0-9]+)/1/")"'/d;s/^[^ ]* [^ ]* ([^ ]*).*/1/;/[0-9]/!d' | xargs sudo apt-get -y purge

You can check what packages will be purged executing the first part of the command:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/(.*)-([^0-9]+)/1/")"'/d;s/^[^ ]* [^ ]* ([^ ]*).*/1/;/[0-9]/!d'

Reference

Use dpkg-query to find the largest packages and remove the ones you don't need anymore (source):

dpkg-query --show --showformat='$Package;-50t$Installed-Sizen' | sort -k 2 -n | grep -v deinstall | awk 'printf "%.3f MB t %sn", $2/(1024), $1'

sudo apt autoclean # clean /var/cache/apt/archives folder which save packages while install.
sudo apt autoremove # this command remove unused packages.

sudo shutdown -rf # it will restart your PC immediately and check filesystem in next boot.

Removing old kernel versions (as suggested already by homebrand) can free up a decent amount of space if you haven't yet got around to doing that.

There's a number of ways to remove the old kernel versions and a range of different options can be found in the answers posted to: How do I remove old kernel versions to clean up the boot menu?

My preferred method is mostly this answer from penreturns where it's broken down into fairly simple understandable steps:

Open terminal and check your current kernel:

uname -r

DO NOT REMOVE THIS KERNEL!

Next, type the command below to view/list all installed kernels on your system.

dpkg --list | grep linux-image

Find all the kernels that are lower than your current kernel.
When you know which kernel to remove, continue below to remove it.

Run the command below to remove the kernel you selected.

sudo apt-get purge linux-image-x.x.x.x-generic

The answer then says to 'update-grub2' when you're finished purging, which is likely to be out of date now: sudo update-grub should suffice for Ubuntu 14.04 onward. They also then say to 'Reboot your system' (which seems to be so that you can see the cleaned up boot menu) so in this case isn't necessary.

The grub bootloader menu used to show all the older kernel versions on the main page, but they are now placed out of the way behind a sub-menu. It's much neater but a newcomer to Ubuntu/Linux may not be aware that they are there taking up space.

As suggested, don't remove the current kernel and it's also advisable to keep the previous kernel version too, just in case you need to roll back to that one.

There are faster ways to do this, but I prefer the simplicity of this method mainly because I can understand each command along the way:

"What kernel version am I using? What kernel versions do I have? Okay, purge that one."

Rinse, repeat, admire the space you've freed up.

It's fairly easy to copy the name of the specific older kernel you want to remove from the results that dpkg --list | grep linux-image gives you in the terminal, and then use sudo apt-get purge and paste the copied name in.

Removing 3 or 4 older kernels will usually free up about a GB of space in your root drive.

Following the instructions on the Ubuntu community docs I discovered a massive trash file -- it looked like a backup of /var/log/syslog.1, presumably something was spewing loads of output to syslog...

The command that found it was:

sudo find / -size +1G

And then any large file in a folder called .Trash is probably good to delete...

When I need make more free space on servers I use this command:

find / -type f -size +50M -exec du -h ; | sort -n

It finds all files bigger than 50 MB and "du -h" make a better list of files and "sort -n" after pipe make list numerically sorted by file size.

Here is a script I run to free space on root partition

function myclean sed '/^ii/!d;/'"$(uname -r 

In Ubuntu, each folder can have its own filesystem. That means you can move any folder onto its own partition, another disk or even on a remote network. This is particularly popular for home directories, since that means you can reinstall Ubuntu without changing your personal settings or loosing any files. It's also popular in networks where users should be able to log onto different machines and still get their personal settings and files. But it is useful in many different cases, such as yours.

Applications aren't installed into a specific folder, like you seem to suggest. Different parts of the application is placed in different parts of the filesystem. The main program is usually placed in /usr/bin, whereas configuration files are placed in /etc, for instance. In your case, MySQL, the databases themselves are placed somewhere in /var. I think /var/mysql.

Since /usr and /var are both directories in the root filesystem, they will use the root filesystems space. But as I said, you can move them to different filesystems. In the case of MySQL, you can configure where databases are stored. You could easily move databases to /home/username/.mysql/databases for instance.

You cannot change the path where the package manager install applications. Most application files are saved to /usr. If you want to recover space on the root partition, moving /usr to a different partition is a possible solution.

From comments:

• Preserve the permissions when copying, i.e. better use the command line if you are unsure what your file manager will do.




• The right way to this, is to mount a new filesystem to /usr or use mount --bind. It's not clear how well a symlink would work.

If you have a lot of seperate filesystems, the following trick might prove handy: Mount / another time, but this time under /mnt. Now all of your searching for large or many files can be done, without traversing wrong fileystems.

It can also help you find the files that are hidden under another mount.

As of today it's better to use the new feature (since 14.04) to remove older kernel images:

sudo apt autoremove

Check out more details: Why doesn't Ubuntu remove old kernels automatically?

If you have mssql database server installed, that can eat up your memory. Run NCurses Disk Usage

$ sudo ncdu / 

To check what folders and files are taking max storage. The mssql data are usually stored on

/var/opt/mssql/backup/