Hi @martinetd and thanks for this!

I would like to include clush bash completion is 1.9.3 if possible, so I've been looking at this today.
I confirm it works however there is one problem I noticed when testing on our cluster Sherlock: -L is way too costly. There, a sysadmin you know defined 32 group sources :-), including various external group sources. Calling cluset -L resolves all groups in all sources and takes up to several minutes to complete.

But I think we might be able to come up with something to only call cluset -l when the user presses TAB (and never -L). But I'm not 100% sure this is doable technically and need your help. Let me explain below.

The idea would be as follow:

• clush -s source -w <TAB>
  Similar to what you propose but I just added -G so that the group source is not repeated (open for discussion):

options="$(cluset -s "$groupsource" -l -G 2>/dev/null)"  

This gives us this on our cluster:

# clush -s pdu -w <TAB>

# clush -s pdu -w @PX
@PX2-1901U-N1A6  @PX3-1901U-N1    @PX3-1901U-N1A6  @PX4-5851-E7V2 

• Now, for -w when -s source is not specified, the idea would be to return groups in the default group sources + "@source:" prefixes for the matching group sources. Something like that:

# clush -w <TAB>
@base           @cpu            @hw:            @island:    ....

Here @base and @cpu are normal groups in the default group source, and @hw: and @island: are group sources.

I got this result from this:

    -w|-x)                                                                      
        if [[ -n "$groupsource" ]]; then                                        
            options="$(cluset -s "$groupsource" -l -G 2>/dev/null)"             
        else                                                                    
            options="$(cluset --groupsources | sed -e 's/ (default)//' -e 's/^/@/' -e 's/$/:/')"
            options+="$(cluset -l 2>/dev/null)"                                 
        fi                                                                      
        ;;  

However, I'm not sure how to trigger a group lookup when we do clush -w @hw:<TAB>. First, bash completion adds a space if I hit TAB after @hw: (that's the first problem) and second, we likely need to call cluset -s hw -l -G to list all groups in the hw source in that case. I'm not sure how to do that. If you have any ideas on how to resolve this... let me know. Should we define another completion function and use complete again?