How to execute curl command stored in heredoc in bash script? - bash

Question

When write bash scripts, I want to store my whole curl command in heredoc to get a better layout. The following works fine:
#/bin/bash
read -r -d '' command1 <<- MULTI_STRING_SCOPE
curl -v www.stackoverflow.com
MULTI_STRING_SCOPE
But when add some json data with the -d option, the command is executed weirdly. For example:
#/bin/bash
read -r -d '' command2 <<- MULTI_STRING_SCOPE
curl -v www.stackoverflow.com
-d '{
"hello":"world"
}'
MULTI_STRING_SCOPE
response2=$(${command2})
Wrong logs from terminal:
curl: (3) URL using bad/illegal format or missing URL
curl: (3) unmatched close brace/bracket in URL position 1:
}'
And it seems that the curl take line }' as a seperated url, and thus the json data not sent as a unit.
How to solve the problem? Any suggestions will be highly appreciated.

Answer 1

I learned from this post to make heredoc work with curl command.
As the comment made by #Gordon Davisson in current post, we should not mix command with data. Since the json data set to -d option is only data and other parts is command, so I decide to use heredoc to store only the json data and remain other parts to be command itself, rather than store them in string by heredoc.
The result bash script should be something like this:
#/bin/bash
response3=$(curl -v www.stackoverflow.com \
-d #- <<- MULTI_STRING_SCOPE
{
"hello":"world"
}
MULTI_STRING_SCOPE
)
Notice: heredoc indent only works with tab, not with blanks. Be careful, especially when you are working with editors like Visual Studio Code, which may have already set indent as blanks for you.