Uploading to Amazon S3 via curl route

You should specify your using bucket name and some parameters for S3. And I guess it's PUT, not POST. There are several command line samples in the internet.

file=/path/to/file/to/upload.tar.gz
bucket=your-bucket
resource="/${bucket}/${file}"
contentType="application/x-compressed-tar"
dateValue=`date -R`
stringToSign="PUT\n\n${contentType}\n${dateValue}\n${resource}"
s3Key=xxxxxxxxxxxxxxxxxxxx
s3Secret=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
signature=`echo -en ${stringToSign} | openssl sha1 -hmac ${s3Secret} -binary | base64`
curl -X PUT -T "${file}" \
  -H "Host: ${bucket}.s3.amazonaws.com" \
  -H "Date: ${dateValue}" \
  -H "Content-Type: ${contentType}" \
  -H "Authorization: AWS ${s3Key}:${signature}" \
  https://${bucket}.s3.amazonaws.com/${file}

• Uploading to S3 in 18 lines of Shell (used to upload builds for http://soltrader.net)
• Uploading to S3 in Bash

    #run this code on ec2 linux with s3 write role 

TOKEN=`curl -s -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"`
xamztoken=`curl -s -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/iam/security-credentials/ec2files3 | jq -r ".Token"`


yyyymmdd=`date +%Y%m%d`
s3Bucket="testfiles3bc"
bucketLocation="us-east-1"
s3SecretKey=`curl -s -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/iam/security-credentials/ec2files3 | jq -r '.SecretAccessKey'`
s3AccessKey=`curl -s -H "X-aws-ec2-metadata-token: $TOKEN"  http://169.254.169.254/latest/meta-data/iam/security-credentials/ec2files3 | jq -r ".AccessKeyId"`
endpoint="testfiles3bc.s3.amazonaws.com"
fileName="image.gif"
contentLength=`cat ${fileName} | wc -c`
contentHash=`openssl sha -sha256 -hex ${fileName} | sed 's/.* //'`
contentType=`file -b --mime-type $fileName`
b64=`openssl md5 -binary "$fileName" | openssl base64`
acl="private"

date=`date -u +%Y%m%dT%H%M%SZ`

expdate_s="2022-12-30T12:00:00.000Z"

region="us-east-1"


p=$(cat <<POLICY | openssl base64 | tr -d \\n
{ "expiration": "${expdate_s}T12:00:00.000Z",
  "conditions": [
    {"acl": "$acl" },
    {"bucket": "$s3Bucket" },
    ["starts-with", "\$key", ""],
    ["starts-with", "$contentType", "image/"],
    {"x-amz-date": "$date" },
    {"content-md5": "$b64" },
    {"x-amz-credential": "${s3AccessKey}/${yyyymmdd}/${region}/s3/aws4_request" },
    {"x-amz-security-token": "${xamztoken}" },
    {"x-amz-algorithm": "AWS4-HMAC-SHA256" }
  ]
}
POLICY
)


stringToSign=$p
echo "----------------- canonicalRequest --------------------"
echo -e ${canonicalRequest}
echo "----------------- stringToSign --------------------"
echo -e ${stringToSign}
echo "-------------------------------------------------------"



# calculate the signing key
DateKey=`echo -n "${yyyymmdd}" | openssl sha -sha256 -hex -hmac "AWS4${s3SecretKey}" | sed 's/.* //'`
DateRegionKey=`echo -n "${bucketLocation}" | openssl sha -sha256 -hex -mac HMAC -macopt hexkey:${DateKey} | sed 's/.* //'`
DateRegionServiceKey=`echo -n "s3" | openssl sha -sha256 -hex -mac HMAC -macopt hexkey:${DateRegionKey} | sed 's/.* //'`
SigningKey=`echo -n "aws4_request" | openssl sha -sha256 -hex -mac HMAC -macopt hexkey:${DateRegionServiceKey} | sed 's/.* //'`
# then, once more a HMAC for the signature
signature=`echo -en ${p} | openssl sha -sha256 -hex -mac HMAC -macopt hexkey:${SigningKey} | sed 's/.* //'`


key_and_sig_args="-F X-Amz-Credential=${s3AccessKey}/${yyyymmdd}/${region}/s3/aws4_request -F X-Amz-Algorithm=AWS4-HMAC-SHA256 -F X-Amz-Signature=$signature -F X-Amz-Date=${date}"


curl -v   \
-F key=$fileName \
-F acl=$acl \
$key_and_sig_args  \
-F "content-md5= ${b64}" \
-F "Policy=$p" \
-F "X-Amz-Security-Token= ${xamztoken}" \
-F "file=@$fileName" \
https://${s3Bucket}.s3.amazonaws.com/