Check if command exists with shell script

2020年10月13日

if ! type gem > /dev/null; then
  echo 'gem command not found.'
fi

More on shell

Simply put a space before the command and it won't be saved to ~/.bash\_history. E.g. qrencode -o out.png "Some secret text"

To upgrade postgres you can run

Open term (or equivalent) and paste the following:

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