Why do I have to use this command twice to execute it?

Question

I made an alias alias goto="cd $@ && source ~/.zshrc" and it works, but only if I execute it twice. Even after I execute it twice in one shell, and if I want to move to another dir, I must again execute it twice. Why is that and how can I change that?

I need to type two times goto <dir>. The first time, I am still in the normal dir and the second time, I got to my destination. I need to source .zshrc, because I have a check for the path:

CURRENT=$PWD
AT_HOME=0
AT_ROOT=0

if [ $PWD = $HOME ]; then
    AT_HOME=1
elif [ $PWD = / ]; then
    AT_ROOT=1
else
    cd ../

    if [ $PWD = $HOME ]; then
        AT_HOME=1
    elif [ $PWD = / ]; then
        AT_ROOT=1
    else
        cd ../

        if [ $PWD = $HOME ]; then
            AT_HOME=1
        elif [ $PWD = / ]; then
            AT_ROOT=1
        fi
    fi
fi

cd $CURRENT

if [ $AT_HOME = 0 ]; then
    if [ $AT_ROOT = 0 ]; then
        ZSH_THEME="prompt-basename"
    else
        ZSH_THEME="prompt-normal"
    fi
else
    ZSH_THEME="prompt-normal"
fi

And it gives me full path (even at /usr/lib/jvm/java-13/bin) and when I source ~/.zshrc, it gives me the path I want (.../java-13/bin). By the way, replacing && with ; does not work neither.

Thanks!

*This is my first Question at stackxchange.com, so please don't be too rough.

Answer 1

First of all, aliases are not functions and do not accept arguments. Rather, aliases are simple substitutions: When you type goto foo on the command line and press Enter, the shell simply replaces goto with the value of the alias, before executing the command line.

Therefore, $@ does not expand to the arguments passed to your alias. In fact, in this case, it expands to the arguments passed to shell or the script you're sourcing. This is why goto works correctly the second time: You have now passed a directory as an argument when sourcing your .zshrc file and $@ will expand to that argument when you declare the alias again.

Additionally, since you're using "double quotes", $@ expands immediately when you declare the alias. To see that this is the case, right after your shell has started up, type alias without arguments to view your aliases.

If you want goto to be able to handle arguments, you should declare it as a function: goto() { cd $@ && ... }

However, as a rule, ⚠️you should not source ~/.zshrc. Depending on what's in your dotfiles, this can lead to all sorts of problems.

Instead, if you've made changes to your .zshrc file and you want to apply them, you should either restart your terminal (by closing the current tab/window and opening a new one) or restart the shell (by typing exec $SHELL).

Answer 2

Marlon's answer works. Instead of making an alias, I did following function:

function goto {
    cd $@ && exec $SHELL
}

And it works perfectly. I also remarked, that sourcing ~/.zshrc takes longer and longer after every call of goto.