bash command to do the sed

AMPLIFY_ENV=$(jq -r '.envName' amplify/.config/local-env-info.json)
REGION=$(jq -r '.providers.awscloudformation.Region' amplify/backend/amplify-meta.json)
STACK_ID=$(jq -r '.providers.awscloudformation.StackId' amplify/backend/amplify-meta.json)
ACCOUNT_ID=$(echo $STACK_ID | sed -r 's/^arn:aws:(.+):(.+):(.+):stack.+$/\3/')
DYNAMO_DB_PHOTO_TABLE_ARN="arn:aws:dynamodb:$REGION:$ACCOUNT_ID:table/Photo-$API_ID-$AMPLIFY_ENV"
S3_TRIGGER_NAME=$(jq -r '.function | to_entries[] | .key' amplify/backend/amplify-meta.json)
sed -i "s/S3_TRIGGER_NAME_PLACEHOLDER/$S3_TRIGGER_NAME/g" amplify/backend/function/$S3_TRIGGER_NAME/$S3_TRIGGER_NAME-cloudformation-template.json
sed -i "s/DYNAMODB_PHOTO_TABLE_ARN_PLACEHOLDER/$DYNAMO_DB_PHOTO_TABLE_ARN/g" amplify/backend/function/$S3_TRIGGER_NAME/$S3_TRIGGER_NAME-cloudformation-template.json

S3Trigger CFN Template

{
	"AWSTemplateFormatVersion": "2010-09-09",
	"Description": "Lambda resource stack creation using Amplify CLI",
	"Parameters": {
		"env": {
			"Type": "String"
		},
		"DynamoDBPhotoTableArn": {
			"Type": "String",
			"Default": "DYNAMODB_PHOTO_TABLE_ARN_PLACEHOLDER"
		}
	},
	"Conditions": {
		"ShouldNotCreateEnvResources": {
			"Fn::Equals": [
				{
					"Ref": "env"
				},
				"NONE"
			]
		}
	},
	"Resources": {
		"LambdaFunction": {
			"Type": "AWS::Lambda::Function",
			"Metadata": {
				"aws:asset:path": "./src",
				"aws:asset:property": "Code"
			},
			"Properties": {
				"Handler": "index.handler",
				"FunctionName": {
					"Fn::If": [
						"ShouldNotCreateEnvResources",
						"S3_TRIGGER_NAME_PLACEHOLDER",
						{
							"Fn::Join": [
								"",
								[
									"S3_TRIGGER_NAME_PLACEHOLDER",
									"-",
									{
										"Ref": "env"
									}
								]
							]
						}
					]
				},
				"Environment": {
					"Variables": {
						"ENV": {
							"Ref": "env"
						},
						"THUMBNAIL_WIDTH": "80",
						"THUMBNAIL_HEIGHT": "80",
						"DYNAMODB_PHOTOS_TABLE_ARN": { "Ref" : "DynamoDBPhotoTableArn" }
					}
				},
				"Role": {
					"Fn::GetAtt": [
						"LambdaExecutionRole",
						"Arn"
					]
				},
				"Runtime": "nodejs8.10",
				"Timeout": "25"
			}
		},
		"LambdaExecutionRole": {
			"Type": "AWS::IAM::Role",
			"Properties": {
				"RoleName": {
					"Fn::If": [
						"ShouldNotCreateEnvResources",
						"S3_TRIGGER_NAME_PLACEHOLDERLambdaRole66924eb7",
						{
							"Fn::Join": [
								"",
								[
									"S3_TRIGGER_NAME_PLACEHOLDERLambdaRole66924eb7",
									"-",
									{
										"Ref": "env"
									}
								]
							]
						}
					]
				},
				"AssumeRolePolicyDocument": {
					"Version": "2012-10-17",
					"Statement": [
						{
							"Effect": "Allow",
							"Principal": {
								"Service": [
									"lambda.amazonaws.com"
								]
							},
							"Action": [
								"sts:AssumeRole"
							]
						}
					]
				}
			}
		},
		"lambdaexecutionpolicy": {
			"DependsOn": [
				"LambdaExecutionRole"
			],
			"Type": "AWS::IAM::Policy",
			"Properties": {
				"PolicyName": "lambda-execution-policy",
				"Roles": [
					{
						"Ref": "LambdaExecutionRole"
					}
				],
				"PolicyDocument": {
					"Version": "2012-10-17",
					"Statement": [
						{
							"Effect": "Allow",
							"Action": [
								"logs:CreateLogGroup",
								"logs:CreateLogStream",
								"logs:PutLogEvents"
							],
							"Resource": {
								"Fn::Sub": [
									"arn:aws:logs:${region}:${account}:log-group:/aws/lambda/${lambda}:log-stream:*",
									{
										"region": {
											"Ref": "AWS::Region"
										},
										"account": {
											"Ref": "AWS::AccountId"
										},
										"lambda": {
											"Ref": "LambdaFunction"
										}
									}
								]
							}
						}
					]
				}
			}
		},
		"AllPrivsForDynamo": {
			"DependsOn": [
				"LambdaExecutionRole"
			],
			"Type": "AWS::IAM::Policy",
			"Properties": {
				"PolicyName": "AllPrivsForDynamo",
				"Roles": [
					{
						"Ref": "LambdaExecutionRole"
					}
				],
				"PolicyDocument": {
					"Version": "2012-10-17",
					"Statement": [
						{
							"Effect": "Allow",
							"Action": [
								"dynamodb:*"
							],
							"Resource": { "Ref" : "DynamoDBPhotoTableArn" }
						}
					]
				}
			}
		},
		"RekognitionDetectLabels": {
			"DependsOn": [
				"LambdaExecutionRole"
			],
			"Type": "AWS::IAM::Policy",
			"Properties": {
				"PolicyName": "RekognitionDetectLabels",
				"Roles": [
					{
						"Ref": "LambdaExecutionRole"
					}
				],
				"PolicyDocument": {
					"Version": "2012-10-17",
					"Statement": [
						{
							"Effect": "Allow",
							"Action": [
								"rekognition:detectLabels"
							],
							"Resource": "*"
						}
					]
				}
			}
		}
	},
	"Outputs": {
		"Name": {
			"Value": {
				"Ref": "LambdaFunction"
			}
		},
		"Arn": {
			"Value": {
				"Fn::GetAtt": [
					"LambdaFunction",
					"Arn"
				]
			}
		},
		"Region": {
			"Value": {
				"Ref": "AWS::Region"
			}
		},
		"LambdaExecutionRole": {
			"Value": {
				"Ref": "LambdaExecutionRole"
			}
		}
	}
}