Shell script whitespace escaping

Question

Edit: This question has been edited for context. 1.sh and 2.sh scripts in the original question are replaced by their real-world implementations: monitor.sh and api-check.sh respectively.

Function:

function checkAlive() {
    script="$1"
    args="${@:2}"
    startCheck=$(date +%s)
    echo "$@"
    tempResult="$( "$@" )"
    T_RC="$?"
    if [ "$T_RC" -ne 0 ]; then
        if [ "$result" = "" ]; then
            result="ERRORS: $tempResult"
        else
            result="$result ,, $tempResult"
        fi
    fi
    RC="$((RC > T_RC ? RC : T_RC))"
    timePassed
}

api-check.sh:

method="$1"
url="https://$2"
jwt="$3"
body="$4"
echo "$body"

if ! response="$(curl -s --request "$method" "$url" -w "%{http_code}" --header \
    'Authorization: Bearer '"$jwt" --header 'Content-Type: application/json' --header 'Accept: application/json' --data-raw "$body")"; then
    echo "$url curl error getting code: $response"
    exit 2
fi

monitor.sh:

api_url="foo"
oauth_token"bar"
body='{"address":"Test address"}'
checkAlive "api-check.sh" '"POST" "'$api_url'" "'$oauth_token'" '"'$body'"''

Execution Flow:

monitor.sh passes the string json body as an argument to checkAlive function (defined above).
Within checkAlive, the echo "$@" returns:

api-check.sh "POST" "foo" "bar" '{"address":"Test address"}'

The api-check.sh script never executes properly due to some escaping issue again

Question: What json body should I pass as an argument to checkAlive to escape correctly OR Which line of code and in which script do I need to modify to evaluate the json body correctly?

The culprit is eval $script $args. First, you don't double-quote your variable expansions ('{"address":"Test address"}' becomes '{"address":"Test' 'address"}'), then even if you double-quote them, eval will jinx it... the correct way is to simply use result="$( "$@" )" — Fravadona
– Fravadona, Commented Jan 26, 2023 at 10:37
If you really need to store all but the first argument, use an array, like args=("${@:2}"), then use it like result=$("$script" "${args[@]}"). Avoid eval, it's extremely hard to use correctly, and almost never necessary. — Gordon Davisson
– Gordon Davisson, Commented Jan 26, 2023 at 10:47
Further, what is the point of checkAlive instead of just calling 2.sh on the given JSON? — chepner
– chepner, Commented Jan 26, 2023 at 13:59

KamilCuk · Accepted Answer · 2023-01-26 16:21:21Z

2

do func() not function func()
just "$var". not anything else. Just make sure any $var is inside " ". Nothing more required.

Do:

api_url="foo"
oauth_token"bar"
body='{"address":"Test address"}'
checkAlive "api-check.sh" "POST" "$api_url" "$oauth_token" "$body"

answered Jan 26, 2023 at 16:21

KamilCuk

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