Hello to all the readers!
I was upgrading my Manjaro linux system. And stumbled upon that the disk space is not sufficient to carry out the upgrade. Therefore, I started hunting what is consuming the disk and is unnecessary, so that it can be cleaned up.
I started running the common du command to find which directory under root is taking up disk space.
$ sudo du -sh /* | sort -hdu stands for Device usage or Disk usage. It calculates total usage of each directory.
But while running this command, I remember that /home is mounted as a separate disk partition and disk space warning is for /. Therefore, I had to skip calculating usage of /home folder. I could find that du provides an option to exclude particular directory. And this is how it works.
$ sudo du -sh --exclude=/home /* | sort -h
0 /bin
0 /dev
0 /lib
0 /lib64
0 /mnt
0 /proc
0 /sbin
0 /snap
0 /srv
0 /sys
8.0K /rootfs-pkgs.txt
24K /desktopfs-pkgs.txt
208K /tmp
2.4M /run
13M /etc
207M /root
266M /boot
3.3G /opt
19G /usr
37G /var
--exclude matches a regex pattern. So, create the exclude pattern carefully.
Okay and now I can see that some unnecessary stuff lies under /var/ directory as cache, logs are stored there.
And after searching more, I could find that it is the pacman that uses around 11 GB of storage /var/cache/pacman/pkg and thereby upgrade fails to download latest packages and put there in the cache.
So I found that pacman keeps downloaded packages in the cache folder even if some previous packages have been uninstalled. Still it keeps those in the cache. Therefore I need to clear this cache to get ample disk back for filesystem operations.
sudo pacman -Sc
Packages to keep:
All locally installed packages
Cache directory: /var/cache/pacman/pkg/
:: Do you want to remove all other packages from cache? [Y/n] Y
removing old packages from cache...
Database directory: /var/lib/pacman/
:: Do you want to remove unused repositories? [Y/n] Y
removing unused sync repositories...