Clearing disk space - What is safe to remove and why 6 GB?

workspace

#1

Hi,

I ran the command du -h -t 50M /and had this returned:

Why is so much returned and what is safe to remove / how can I remove it?

(master) $ du -h -t 50M /
du: cannot read directory ‘/etc/ssl/private’: Permission denied
du: cannot read directory ‘/etc/couchdb/local.d’: Permission denied
du: cannot read directory ‘/etc/polkit-1/localauthority’: Permission denied
du: cannot read directory ‘/root’: Permission denied
55M /home/ubuntu/.cache
122M /home/ubuntu/workspace/GoalMates
127M /home/ubuntu/workspace
66M /home/ubuntu/.local/share/heroku/client/7.0.26/node_modules
101M /home/ubuntu/.local/share/heroku/client/7.0.26
63M /home/ubuntu/.local/share/heroku/client/7.0.47/node_modules
99M /home/ubuntu/.local/share/heroku/client/7.0.47
200M /home/ubuntu/.local/share/heroku/client
206M /home/ubuntu/.local/share/heroku
206M /home/ubuntu/.local/share
206M /home/ubuntu/.local
442M /home/ubuntu
442M /home
66M /usr/local/rvm/archives
102M /usr/local/rvm/rubies/ruby-2.3.1/lib
103M /usr/local/rvm/rubies/ruby-2.3.1
52M /usr/local/rvm/rubies/ruby-2.4.2/lib
53M /usr/local/rvm/rubies/ruby-2.4.2
103M /usr/local/rvm/rubies/ruby-2.3.0/lib
103M /usr/local/rvm/rubies/ruby-2.3.0
258M /usr/local/rvm/rubies
131M /usr/local/rvm/gems/ruby-2.3.0/cache
720M /usr/local/rvm/gems/ruby-2.3.0/gems
899M /usr/local/rvm/gems/ruby-2.3.0
158M /usr/local/rvm/gems/ruby-2.3.1/gems
194M /usr/local/rvm/gems/ruby-2.3.1
93M /usr/local/rvm/gems/ruby-2.4.2/gems
119M /usr/local/rvm/gems/ruby-2.4.2
1.2G /usr/local/rvm/gems
1.6G /usr/local/rvm
113M /usr/local/heroku/node_modules
147M /usr/local/heroku
1.7G /usr/local
328M /usr/lib/x86_64-linux-gnu
93M /usr/lib/valgrind
70M /usr/lib/python2.7
78M /usr/lib/jvm/java-7-openjdk-amd64/jre/lib
78M /usr/lib/jvm/java-7-openjdk-amd64/jre
78M /usr/lib/jvm/java-7-openjdk-amd64
78M /usr/lib/jvm
870M /usr/lib
182M /usr/bin
155M /usr/share/doc
70M /usr/share/emacs/24.3
70M /usr/share/emacs
580M /usr/share
114M /usr/include/boost
151M /usr/include
3.5G /usr
103M /var/cache/apt/apt-file
103M /var/cache/apt
du: cannot read directory ‘/var/cache/ldconfig’: Permission denied
110M /var/cache
du: cannot read directory ‘/var/log/exim4’: Permission denied
du: cannot read directory ‘/var/log/mysql’: Permission denied
du: cannot read directory ‘/var/log/apache2’: Permission denied
du: cannot read directory ‘/var/log/couchdb’: Permission denied
du: cannot read directory ‘/var/lib/php5’: Permission denied
du: cannot read directory ‘/var/lib/mysql’: Permission denied
du: cannot read directory ‘/var/lib/postgresql/9.3/main’: Permission denied
du: cannot read directory ‘/var/lib/sudo’: Permission denied
du: cannot read directory ‘/var/lib/mysql-files’: Permission denied
du: cannot read directory ‘/var/lib/couchdb’: Permission denied
du: cannot read directory ‘/var/lib/polkit-1’: Permission denied
71M /var/lib
du: cannot read directory ‘/var/spool/exim4’: Permission denied
du: cannot read directory ‘/var/spool/rsyslog’: Permission denied
du: cannot read directory ‘/var/spool/cron/crontabs’: Permission denied
182M /var
du: cannot read directory ‘/lost+found’: Permission denied
du: cannot read directory ‘/run/exim4’: Permission denied
du: cannot read directory ‘/nix/.cache’: Permission denied
55M /nix/store/cz8sfjinal66y350ynyz89vihihcn7k6-gcc-4.9.3/libexec/gcc/x86_64-unknown-linux-gnu/4.9.3
55M /nix/store/cz8sfjinal66y350ynyz89vihihcn7k6-gcc-4.9.3/libexec/gcc/x86_64-unknown-linux-gnu
55M /nix/store/cz8sfjinal66y350ynyz89vihihcn7k6-gcc-4.9.3/libexec/gcc
55M /nix/store/cz8sfjinal66y350ynyz89vihihcn7k6-gcc-4.9.3/libexec
99M /nix/store/cz8sfjinal66y350ynyz89vihihcn7k6-gcc-4.9.3
68M /nix/store/d1prcspbh2qsviipvnaxizcj8l3g7fpw-bootstrap-tools/libexec/gcc/x86_64-unknown-linux-gnu/5.3.0
68M /nix/store/d1prcspbh2qsviipvnaxizcj8l3g7fpw-bootstrap-tools/libexec/gcc/x86_64-unknown-linux-gnu
68M /nix/store/d1prcspbh2qsviipvnaxizcj8l3g7fpw-bootstrap-tools/libexec/gcc
68M /nix/store/d1prcspbh2qsviipvnaxizcj8l3g7fpw-bootstrap-tools/libexec
114M /nix/store/d1prcspbh2qsviipvnaxizcj8l3g7fpw-bootstrap-tools
106M /nix/store/lrd5wjp4151wmflci68i8vd7a9a4lwmb-glibc-locales-2.23/lib/locale
106M /nix/store/lrd5wjp4151wmflci68i8vd7a9a4lwmb-glibc-locales-2.23/lib
106M /nix/store/lrd5wjp4151wmflci68i8vd7a9a4lwmb-glibc-locales-2.23
61M /nix/store/3fyzfkv0k3d1ymfv25d2k7kqbpibhl1r-gccgo49-4.9.3/libexec/gcc/x86_64-unknown-linux-gnu/4.9.3
61M /nix/store/3fyzfkv0k3d1ymfv25d2k7kqbpibhl1r-gccgo49-4.9.3/libexec/gcc/x86_64-unknown-linux-gnu
61M /nix/store/3fyzfkv0k3d1ymfv25d2k7kqbpibhl1r-gccgo49-4.9.3/libexec/gcc
61M /nix/store/3fyzfkv0k3d1ymfv25d2k7kqbpibhl1r-gccgo49-4.9.3/libexec
67M /nix/store/3fyzfkv0k3d1ymfv25d2k7kqbpibhl1r-gccgo49-4.9.3/lib
151M /nix/store/3fyzfkv0k3d1ymfv25d2k7kqbpibhl1r-gccgo49-4.9.3
70M /nix/store/zmisxnl63ica4zaviifixamr3xg27kzp-ruby-2.3.1-p0/share/ri/2.3.0/system
70M /nix/store/zmisxnl63ica4zaviifixamr3xg27kzp-ruby-2.3.1-p0/share/ri/2.3.0
70M /nix/store/zmisxnl63ica4zaviifixamr3xg27kzp-ruby-2.3.1-p0/share/ri
70M /nix/store/zmisxnl63ica4zaviifixamr3xg27kzp-ruby-2.3.1-p0/share
107M /nix/store/zmisxnl63ica4zaviifixamr3xg27kzp-ruby-2.3.1-p0
52M /nix/store/adnbhcy51b4x19fmfci6h0qfy5sarwpr-python-2.7.11/lib/python2.7
54M /nix/store/adnbhcy51b4x19fmfci6h0qfy5sarwpr-python-2.7.11/lib
55M /nix/store/adnbhcy51b4x19fmfci6h0qfy5sarwpr-python-2.7.11
51M /nix/store/7nygbmc03nxm24iz59s6gwwh9j1q5ham-nixpkgs/nixpkgs/pkgs/development/haskell-modules
77M /nix/store/7nygbmc03nxm24iz59s6gwwh9j1q5ham-nixpkgs/nixpkgs/pkgs/development
128M /nix/store/7nygbmc03nxm24iz59s6gwwh9j1q5ham-nixpkgs/nixpkgs/pkgs
134M /nix/store/7nygbmc03nxm24iz59s6gwwh9j1q5ham-nixpkgs/nixpkgs
134M /nix/store/7nygbmc03nxm24iz59s6gwwh9j1q5ham-nixpkgs
100M /nix/store/gphrkb6lzn9bf7db2q1z00ypfdh46lma-node-sources/deps
136M /nix/store/gphrkb6lzn9bf7db2q1z00ypfdh46lma-node-sources
69M /nix/store/l8y2srrkp5fflwph7vq0gllj1k1ai17w-gcc-5.3.0/libexec/gcc/x86_64-unknown-linux-gnu/5.3.0
69M /nix/store/l8y2srrkp5fflwph7vq0gllj1k1ai17w-gcc-5.3.0/libexec/gcc/x86_64-unknown-linux-gnu
69M /nix/store/l8y2srrkp5fflwph7vq0gllj1k1ai17w-gcc-5.3.0/libexec/gcc
69M /nix/store/l8y2srrkp5fflwph7vq0gllj1k1ai17w-gcc-5.3.0/libexec
116M /nix/store/l8y2srrkp5fflwph7vq0gllj1k1ai17w-gcc-5.3.0
68M /nix/store/w1vk7050ib5vi1qlqr80s3hfvx4ni5cm-python3-3.5.1/lib/python3.5
71M /nix/store/w1vk7050ib5vi1qlqr80s3hfvx4ni5cm-python3-3.5.1/lib
72M /nix/store/w1vk7050ib5vi1qlqr80s3hfvx4ni5cm-python3-3.5.1
1.9G /nix/store
2.0G /nix
86M /opt/go/pkg/tool/linux_amd64
86M /opt/go/pkg/tool
148M /opt/go/pkg
253M /opt/go
253M /opt
52M /mnt/shared/benchmark/go
52M /mnt/shared/benchmark
99M /mnt/shared/lib/node_modules
51M /mnt/shared/lib/python2/lib/python2.7/site-packages/codeintel/codeintel2/stdlibs
68M /mnt/shared/lib/python2/lib/python2.7/site-packages/codeintel/codeintel2
87M /mnt/shared/lib/python2/lib/python2.7/site-packages/codeintel
109M /mnt/shared/lib/python2/lib/python2.7/site-packages
110M /mnt/shared/lib/python2/lib/python2.7
110M /mnt/shared/lib/python2/lib
110M /mnt/shared/lib/python2
258M /mnt/shared/lib
52M /mnt/shared/plugins/salesforce.sync/kracht/node_modules
56M /mnt/shared/plugins/salesforce.sync/kracht
76M /mnt/shared/plugins/salesforce.sync
91M /mnt/shared/plugins
414M /mnt/shared
414M /mnt
du: cannot read directory ‘/proc/tty/driver’: Permission denied
du: cannot read directory ‘/proc/1/task/1/fd’: Permission denied
du: cannot read directory ‘/proc/1/task/1/fdinfo’: Permission denied
du: cannot read directory ‘/proc/1/task/1/ns’: Permission denied
du: cannot read directory ‘/proc/1/fd’: Permission denied
du: cannot read directory ‘/proc/1/map_files’: Permission denied
du: cannot read directory ‘/proc/1/fdinfo’: Permission denied
du: cannot read directory ‘/proc/1/ns’: Permission denied
du: cannot read directory ‘/proc/7/task/7/fd’: Permission denied
du: cannot read directory ‘/proc/7/task/7/fdinfo’: Permission denied
du: cannot read directory ‘/proc/7/task/7/ns’: Permission denied
du: cannot read directory ‘/proc/7/fd’: Permission denied
du: cannot read directory ‘/proc/7/map_files’: Permission denied
du: cannot read directory ‘/proc/7/fdinfo’: Permission denied
du: cannot read directory ‘/proc/7/ns’: Permission denied
du: cannot read directory ‘/proc/2268/task/2268/fd’: Permission denied
du: cannot read directory ‘/proc/2268/task/2268/fdinfo’: Permission denied
du: cannot read directory ‘/proc/2268/task/2268/ns’: Permission denied
du: cannot read directory ‘/proc/2268/fd’: Permission denied
du: cannot read directory ‘/proc/2268/map_files’: Permission denied
du: cannot read directory ‘/proc/2268/fdinfo’: Permission denied
du: cannot read directory ‘/proc/2268/ns’: Permission denied
du: cannot access ‘/proc/2755/task/2755/fd/4’: No such file or directory
du: cannot access ‘/proc/2755/task/2755/fdinfo/4’: No such file or directory
du: cannot access ‘/proc/2755/fd/3’: No such file or directory
du: cannot access ‘/proc/2755/fdinfo/3’: No such file or directory
6.7G /