-1
 $ pip install -U $(pip list --outdated 2> /dev/null | grep -v 'Version' | grep -v '------' | awk '{printf $1 " " }' && echo)

April 16, 2020, 1:04 p.m.docdyhr

Explanation

I find it annoying that I have to cut & paste individual packages to 'pip install -U PACKAGE_NAMES...' to upgrade all python packages in a specific python installation.