Bash – How to add a variable to this curl command

bashcurllinux

I have a curl command that sends a string of text to the server and I've been trying to figure out how to either have the string of text come from a file or from a bash variable. The command looks like this:

curl -X POST -u "apikey:<apikey>"
--header "Content-Type: application/json"
--data '{"text": "<variable>"}'
"<url>"

I can't figure out how to get a variable in there. I've tried replacing with $variable and $(< file) but I don't know how to get those to spit out text without an echo and I can't echo in a curl.

Best Answer

Stop the single quoted string, follow with the variable expansion, posibly double quoted, and resume the single quoted string:

--data '{"text": "'"$variable"'"}'

($variable should still expand to something that together with the surroundings forms legal JSON, or else the other side probably won't be very happy :) .)

Related Solutions

Curl – How to Check if a Command Completed Without Error

The simplest way is to store the response and compare it:

$ response=$(curl -X POST -d@myfile.txt server-URL);
$ if [ "Upload successful" == "${response}" ]; then … fi;

I haven't tested that. The syntax might be off, but that's the idea. I'm sure there are more sophisticated ways of doing it such as checking curl's exit code or something.

update

curl returns quite a few exit codes. I'm guessing a failed post might result in 55 Failed sending network data. So you could probably just make sure the exit code was zero by comparing to $? (Expands to the exit status of the most recently executed foreground pipeline.):

$ curl -X POST -d@myfile.txt server-URL;
$ if [ 0 -eq $? ]; then … fi;

Or if your command is relatively short and you want to do something when it fails, you could rely on the exit code as the condition in a conditional statement:

$ if curl --fail -X POST -d@myfile.txt server-URL; then
    # …(success)
else
    # …(failure)
fi;

I think this format is often preferred, but personally I find it less readable.

Best Answer

Related Solutions

Curl – How to Check if a Command Completed Without Error

update

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