Access Bash array without trailing commas

Question

This is a simple question but I couldn't find the answer to it. I've got an array of IPs that I want to distribute a file to and don't want to execute separate scp commands each time. I designed this bash function to do this for me:

function scp_Targets () {
    loopControl=0
    declare -a targets=("200.150.100.2", "200.150.100.3", "200.150.100.4")
    arraySize=${#targets[@]}

    while [ $loopControl -lt $arraySize ]
    do
        echo "hello, loopControl is $loopControl, targetValue is ${targets[$loopControl]}"
        scp $1 root@${targets[$loopControl]}:$2
        if [ $? -eq 0 ]
        then
                echo "Transferred $1 to $2 on target at ${targets[$loopControl]}"
        fi
        ((loopControl++))
    done
}

Which spits out

hello, loopControl is 0, targetValue is 200.150.100.2,
ssh: Could not resolve hostname 200.150.100.2,: Name or service not known
lost connection
hello, loopControl is 1, targetValue is 200.150.100.3,
ssh: Could not resolve hostname 200.150.100.3,: Name or service not known
lost connection
hello, loopControl is 2, targetValue is 200.150.100.4
[email protected]'s password: 
script.sh                                                                                                                                                              
100%  326     0.3KB/s   00:00    
Transferred script.sh to /usr/bin on target at 200.150.100.4

Wheras I wanted

hello, loopControl is 0, targetValue is 200.150.100.2
[email protected]'s password: 
script.sh                                                                                                                                                              
100%  326     0.3KB/s   00:00    
Transferred script.sh to /usr/bin on target at 200.150.100.2
... (same for the other two IPs)

Which shows me that accessing the array includes a trailing comma, is this a side effect of how I'm accessing the array? How can I get the commas out of the values? I'm aware I could do length checks and then just remove the last character, but it seems like there should be a more obvious way.

declare -a targets=("200.150.100.2" "200.150.100.3" "200.150.100.4") It should not have comma here — anubhava
– anubhava, Commented Feb 15, 2018 at 21:25

Gilles Quénot · Accepted Answer · 2018-02-15 21:44:25Z

2

You can trim all commas , with this simple bash parameter expansion :

$ declare -a targets=("200.150.100.2", "200.150.100.3", "200.150.100.4")
$ new_targets="${targets[@]%,}"
$ printf '%s\n' "${new_targets[@]}"
200.150.100.2 200.150.100.3 200.150.100.4

answered Feb 15, 2018 at 21:44

Gilles Quénot

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2 Comments

Barmar Over a year ago

But it's simpler not to write the commas in the first place, isn't it?

Gilles Quénot Over a year ago

For sure @Barmar :)

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