Replace string in text file with PowerShell - powershell

Question

I am attempting to replace a string in a text file on a specific line number using PowerShell but the command is removing a majority of the content. I would like to leverage the line number because the string to be replaced occurs on several lines but only want the string on line 51 to be updated. I am currently attempting to use the following to perform the replacement:
$content = Get-Content "file.txt"
$contentUpdate = $content[51] -replace '"Endpoint": ""','"Endpoint": "bucket.s3.us-west-1.vpce.amazonaws.com",'
Set-Content file.txt $contentUpdate
When the above commands are run against the file referenced at the bottom of this question, only the following remains in the file:
"Region": "",
File content:
{
"Profile":{
"ShareCreds" : true,
"ShareProfile" : "",
"ForceUpdateCreds" : false,
"KeyAutoRotateDays": 0
},
"Mds": {
"CommandWorkersLimit" : 5,
"StopTimeoutMillis" : 20000,
"Endpoint": "",
"CommandRetryLimit": 15
},
"Ssm": {
"Endpoint": "",
"HealthFrequencyMinutes": 5,
"CustomInventoryDefaultLocation" : "",
"AssociationLogsRetentionDurationHours" : 24,
"RunCommandLogsRetentionDurationHours" : 336,
"SessionLogsRetentionDurationHours" : 336,
"PluginLocalOutputCleanup": "",
"OrchestrationDirectoryCleanup": ""
},
"Mgs": {
"Region": "us-west-1",
"Endpoint": "",
"StopTimeoutMillis" : 20000,
"SessionWorkersLimit" : 1000,
"DeniedPortForwardingRemoteIPs" : [
"169.254.169.254",
"fd00:ec2::254",
"169.254.169.253",
"fd00:ec2::253"
]
},
"Agent": {
"Region": "",
"OrchestrationRootDir": "",
"SelfUpdate": false,
"TelemetryMetricsToCloudWatch": false,
"TelemetryMetricsToSSM": true,
"AuditExpirationDay" : 7,
"LongRunningWorkerMonitorIntervalSeconds": 60
},
"Os": {
"Lang": "en-US",
"Name": "",
"Version": "1"
},
"S3": {
"Endpoint": "",
"Region": "",
"LogBucket":"",
"LogKey":""
},
"Kms": {
"Endpoint": ""
}
}

Answer 1

Well, seeing that this is a JSON you're working with, I would treat it as such:
$content = Get-Content "file.txt" -Raw | ConvertFrom-Json
$content.S3.Endpoint = "bucket.s3.us-west-1.vpce.amazonaws.com"
$content | ConvertTo-Json | Set-Content "file.txt"
This way you avoid trying to index through an array and work with the objects themselves.