uname -r'/q;p' | xargs sudo apt-get -y purgenation (remember, | uses the output of the previous command as the input to the next)dpkg --list lists all installed packagesgrep linux-image looks for the installed linux imagesawk '{ print $2 }' just outputs the 2nd column (which is the package name)sort -V puts the items in order by version numbersed -n '/'`uname -r`'/q;p' prints the lines before the current kernelxargs sudo apt-get -y purge purges the found kernelssed invocation:-n tells sed to be quiet`uname -r` outputs the current installed kernel release - we include it in backticks so that the output is includes as part of the command (you might also see this as $(uname -r)/something/q says stop when you match 'something' (in this case, something is output of uname -r) - the / surround a regular expressionp is print; is the command separtor, so /something/q;p says quit when you match something, else printsed -n '/'`uname -r`'/q;p' is print the lines until it matches with the current kernel name.