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I'm facing problem in using multiple alias in a single line on Mac bash Terminal. I have setup below alias in my .bash_profile file

alias gc=gcloud
alias cmp=compute
alias ins=instances
alias pdev="--project=devproj-12891"
function listgce(){
    gcloud compute instances list --project "$1"
}

all those are available as alias individually and can be used but when I try to use multiple of these on a single command, bash evaluates to only first one. Example :

~ % gc cmp ins list pdev
ERROR: (gcloud) Invalid choice: 'cmp'.
Maybe you meant:
  gcloud compute instances

Can please someone guide me if I'm doing something wrong in this ?

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1 Answer 1

Reset to default
7

This is possible in bash: if the last character of an alias definition is a space (or tab), then bash will unalias the next word too:

$ alias foo="echo "
$ alias bar="hello "
$ alias baz=world
$ foo bar baz
hello world

Ref: 6.6 Aliases in the manual.

So you can chain aliases together: but the first word must be an alias.

I would not use aliases though: it's quite subtle and probably brittle. I'd use a function, something like

gc() {
    local -A translation=(
        [cmp]=compute
        [ins]=instances
        [pdev]="--project=devproj-12891"
    )
    local -a args
    for arg in "$@"; do
        if [[ -v "translation[$arg]" ]]; then
            args+=("${translation[$arg]}")
        else
            args+=("$arg")
        fi
    done
    echo gcloud "${args[@]}"
}

Then

$ gc cmp ins list pdev
gcloud compute instances list --project=devproj-12891

Remove the echo if it looks good.

Update to address shortcut "ci" adding 2 words "compute" "instances":

This is a special case because we don't want to add one single quoted item to the args, but two. Let me rewrite that function for greater extensibility:

gc() {
    local -a args
    for arg in "$@"; do
        case $arg in
            cmp)  args+=( compute ) ;;
            ins)  args+=( instances ) ;;
            ci)   args+=( compute instances ) ;;
            pdev) args+=( "--project=devproj-12891" );;
            *)    args+=( "$arg" ) ;;
        esac
    done
    echo gcloud "${args[@]}"
}
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  • I want to add another shortcut "ci" for "compute instances" but when I add that and run the gcloud command, it throws me an error : 2LKMD6R ~ % g ci list poc list project poc has been set compute instances list --project=poc-proj-123 ERROR: (gcloud) Invalid choice: 'compute instances'. Maybe you meant: gcloud compute instances However, if I pass it as two arguments c and i , it translates to two argument and the command works fine is there some trick to add two words together ? Commented Dec 22, 2020 at 19:49
  • Added an update to my answer. See how it's more flexible? Commented Dec 22, 2020 at 20:58
  • Thanks very much Glenn . Other approach I found to original solution is to split words at white space args+=($=translation[$arg]) Commented Dec 22, 2020 at 21:47
  • $=? are you using zsh? Commented Dec 22, 2020 at 23:27
  • 1
    Be aware that bash and zsh are different languages. bash will not understand $=translation[$arg]. Be sure to use the appropriate shebang for your scripts. Commented Dec 23, 2020 at 19:57

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