prints file sizes in megabytes

ls -l --block-size=M

counts files in directory

ls -1 | wc -l

sorts files by time (-tr to reverse order)

ls -t -l

sorts files by size (-Sr to reverse)

ls -S -l

find files containig text

grep -r TEXT *

if you want to download a list of files

wget -i <urls class="txt"></urls>

add prefix to all .csv files in directory

for file in *.csv; do   mv "$file" "preix_${file}"; done

upgrade all pip packages (caraful may beak some versions dependencies)

pip freeze --local | grep -v '^\-e' | cut -d = -f 1  | xargs -n1 sudo pip install -U

copy file contents to clipboard

cat ~/.ssh/id_rsa | xclip -sel clip