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I've written a quick-and-dirty script to time some reports from a web service:


for report_code in $(seq 1 $FINAL); do
  (time -p response=$(curl --write-out %{http_code} --silent -O ${BASE_URL}/${report_code}) ) 2> ${report_code}.time

  echo $response  # <------- this is out of scope!  How do I fix that?
  if [[ $response = '404' ]]; then
    echo "Deleting report # ${report_code}!"
    rm ${report_code}
    echo "${report_code} seems to be good!"

I need to wrap the time command in a subshell so I can redirect its output, but that makes the value of $response unavailable to the parent shell. How do I get around this problem?

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up vote 6 down vote accepted

You can't bring a variable's value from a subshell to its parent, not without doing some error-prone marshalling and cumbersome communication.

Fortunately, you don't need a subshell here. Redirection only requires command grouping with { … }, not a subshell.

{ time -p response=$(curl --write-out '%{http_code}' --silent -O "${BASE_URL}/${report_code}"); } 2> "${report_code}.time"

(Don't forget double quotes around variable substitutions.)

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