It is possible to get the uploadId of the publication when using DEBUG verbosity.
To do so, use the following commands:
uploadId=$(ftpub publish [path/to/directory/or/file] -s [a_source_id] -a [api_key] [ft_portal_URL] -v DEBUG 2>&1 | grep -oE '\\"uploadId\\":\\"([^\\"]+)\\"' | cut -d'"' -f4 | sed 's/\\$//')
echo "Extracted uploadId: $uploadId"
$output = ftpub publish [path/to/directory/or/file] -s [a_source_id] -a [api_key] [ft_portal_URL] -v DEBUG 2>&1
$uploadIdPattern = '\\\"uploadId\\\":\\\"([^\\\"]+)\\\"'
$match = $output | Select-String -Pattern $uploadIdPattern
$uploadId = $match.Matches.Groups[1].Value
Write-Output "Extracted uploadId: $uploadId"
Use the uploadId value with the Get a publish report web service to know the publication status of the document, its URL, etc.