Ubuntu – Why doesn’t the `time` command work with any option

This is because time is a bash builtin command - and the builtin doesn't support the options you're trying to use.

Try this, use the full path of time to skip the built-in and use the real one:

/usr/bin/time -f "%E" ls -l

Your bash alias is not well written (the single quotes are not well used). Instead it should be:

alias rm~='find . -name "*~" -print0 | xargs -0 /bin/rm -f'

Now, I personally don't like useless uses of pipes and xargs, so your alias would be better written as:

alias rm~='find . -name "*~" -type f -exec /bin/rm -fv -- {} +'

The -type f option so as to find only files (not directories, links, etc.), the -v option to rm so as to be verbose (prints out what it's deleting). The + at the end so that find runs rm with all the found files (spawns only one instance of rm, instead of one per file).

Now from man bash:

For almost every purpose, aliases are superseded by shell functions.

Instead of an alias, it's better to use a function: comment your alias in the .bash_aliases file (i.e., put a # in front of that line), and in the file .bashrc, put this function (anywhere in the file, at the end is fine):

rm~() {
    find . -name "*~" -type f -exec /bin/rm -fv -- {} +
}

Also, as the other answer mentions, you can use the -delete command to find. In this case, your rm~ function will be:

rm~() {
    find . -name "*~" -type f -printf "Removing file %p\n" -delete
}

In fact, you can make a cool function that will take an argument, say --dry-run, that will only output what it will delete:

rm~() {
    case "$1" in
    "--dry-run")
        find . -name "*~" -type f -printf "[dry-run] Removing file %p\n"
        ;;
    "")
        find . -name "*~" -type f -printf "Removing file %p\n" -delete
        ;;
    *)
        echo "Unsupported option \`$1'. Did you mean --dry-run?"
        ;;
    esac
}

Then use as:

rm~ --dry-run

to only show the files that will be deleted (but not delete them) and then

rm~

when you're happy with this.

Adapt and extend to your needs!

Note. You'll have to open a new terminal for the changes to take effect.