matching/debugging a php curl request to using curl in bash in a script or cli

curl_php_vs_bash.sh

#!/usr/bin/env bash

# These examples provide some simple and quick ways to experiment
# with the differences between PHP curl requests and using the 
# curl command from a bash shell or script. The commands are arranged
# so they can be easily copy and pasted into a shell for experimenting.

# Use netcat listening locally for testing running netcat from one
# shell and execute the client requests from a separate shell. This
# can be useful to see newline characters and any additional characters
# in the data submitted if it is represented the same by the curl implementation.
# nc -l 8888
# change host address to http://localhost:8888 for sending requests
# to the listening netcat process




# PHP version of sending post data with curl
echo "---------PHP curl use---------"

set +H # disable history expansion
PHP_CODE=$(cat <<'PHP_CODE'
<?php

# Echo requests back from httpbin.org
$host = 'https://httpbin.org/post';

$post_content = <<<EOD
MULTI-LINE
      line with leading spaces
          CONTENT             
line with trailing spaces     
tada!   
EOD;

# Debugging Request - capturing verbose output
# https://blog.kettle.io/debugging-curl-requests-in-php/
ob_start();  
$out = fopen('php://output', 'w');

$headers = [
    'Content-Type:text/plain',
    'X-MySpeacialHeader: LotsOfSpecialnessHere',
    'X-SomeFlag: 1',
];

$ch = curl_init($host);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_content);

# Debugging Request - curl options
curl_setopt($ch, CURLOPT_VERBOSE, true);
curl_setopt($ch, CURLOPT_STDERR, $out);

$response = curl_exec($ch);
curl_close ($ch);

# Debugging Request - close and capture output buffer
fclose($out);  
$debug = ob_get_clean();

print_r($debug);
echo "\n---------\n";
echo "Response\n";
echo $response . "\n";
PHP_CODE
)
set -H # re-enable history expansion
echo "${PHP_CODE}" | php




# Bash version of sending post data with curl
echo "---------Bash curl use---------"

XML_PAYLOAD=$(cat <<XML_HEREDOC
MULTI-LINE
      line with leading spaces
          CONTENT             
line with trailing spaces     
tada!   
XML_HEREDOC
)

# 'echo -n' allows for not adding a newline character to end of contents
# '--trace-ascii -' sends trace debug details to standard output STDOUT
# '--header "User-Agent:"' removes the user-agent from the HTTP request
# '--data-binary' prevents curl from manipulating line endings on text files
# '-@' indicates curl should accept data from the standard input STDIN (what we are piping in)
echo -n "${XML_PAYLOAD}" \
  | curl -s \
      -X POST \
      --trace-ascii - \
      --header 'User-Agent:' \
      --header "Content-Type: text/plain" \
      --header "X-MySpeacialHeader: LotsOfSpecialnessHere" \
      --header "X-SomeFlag: 1" \
      --data-binary @- \
      "https://httpbin.org/post" \