7

Yes, this is related to Getting curl to output HTTP status code? but unfortunately not the same.

In a script I would like to run:

curl -qSfsw %{http_code} URL

where the -f option ensures that the exit code is non-zero to signal an error. On success I want to get the (textual) output from the fetched file, whereas otherwise I want to use the error code.

Problem:

  • Due to race conditions I must not use more than a single HTTP request
  • I cannot use a temporary file for storage of the content

How can I still split the HTTP return code from the actual output?

Pseudo code:

fetch URL
if http-error then
  print http-error-code
else
  print http-body # <- but without the HTTP status code
endif
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1 Answers1

18

There is no need to use a temporary file. The following bash script snippet send a single request and prints the exit code of curl and the HTTP status code, or the HTTP status code and response, as appropriate.

# get output, append HTTP status code in separate line, discard error message
OUT=$( curl -qSfsw '\n%{http_code}' http://superuser.com ) 2>/dev/null

# get exit code
RET=$?

if [[ $RET -ne 0 ]] ; then
    # if error exit code, print exit code
    echo "Error $RET"

    # print HTTP error
    echo "HTTP Error: $(echo "$OUT" | tail -n1 )"
else
    # otherwise print last line of output, i.e. HTTP status code
    echo "Success, HTTP status is:"
    echo "$OUT" | tail -n1

    # and print all but the last line, i.e. the regular response
    echo "Response is:"
    echo "$OUT" | head -n-1
fi

head -n-1 (print all but the last line) requires GNU, doesn't work on BSD/OS X.

Daniel Beck
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