[SOLVED] How to resolve curl: (6) Couldn't resolve host

Issue

I am trying to invoke rest api using curl in a loop as shown below. It doesn't work and throws error curl: (6) Couldn't resolve host '$SERVERPROTOCOL:' However, if replace all environment variables and execute command then it works just fine.

Direct command which works:

curl -X DELETE -k -H 'Content-Type: application/xml' -H 'Accept: application/xml' -u 'testuser:test123' -i 'https://nonprodhost:443/process/cancel/pvm:0a126'

Curl in loop which throws - curl: (6) Couldn't resolve host '$SERVERPROTOCOL:'

for pi in $(cat $halted_pid);do
    # write PID to console so user knows script is working
    echo
    echo "cacnelling process instance - $pi"
    # 2>&1 to include any output on stderr
    curl -X DELETE -k -H 'Content-Type: application/xml' -H 'Accept: application/xml' -u '$USERNAME:USERPASS' -i '$SERVERPROTOCOL://$SERVERHOST:$SERVERPORT/process/cancel/$pi' 2>&1 | tee -a $halted_pi_cancellation_logfile
done

Solution

Why I think issue is single quote? Try replacing single quotes with double quotes

(reference: https://www.php.net/manual/en/language.types.string.php#language.types.string.syntax.double )

curl -X DELETE -k -H 'Content-Type: application/xml' -H 'Accept: application/xml' -u '$USERNAME:USERPASS' -i '$SERVERPROTOCOL://$SERVERHOST:$SERVERPORT/process/cancel/$pi' 2>&1 | tee -a $halted_pi_cancellation_logfile

convert to:

curl -X DELETE -k -H "Content-Type: application/xml" -H "Accept: application/xml" -u "$USERNAME:USERPASS" -i "$SERVERPROTOCOL://$SERVERHOST:$SERVERPORT/process/cancel/$pi" 2>&1 | tee -a $halted_pi_cancellation_logfile

Answered By - Smruti ranjan Gochhayat