Powershell - Pattern Matching - powershell

Question

I have a requirement wherein the log file has some IP address and it needs to be replaced with hostname referring the database. I am getting output with matches for hostname found in database. I am unable to print the IP address for which hostname not found as it is.Can anyone assist in getting the full output.
IP_Address.txt
dhhdhja sasa 10.1.154.6
sasas swssss 10.1.154.10
assas 10.1.154.14
10.1.154.34
10.1.154.38
Hostname.txt
10.1.154.6=>Host1
10.1.154.10=>Host2
10.1.154.14=>Host3
Current Output
dhhdhja sasa 10.1.154.6=>Host1
sasas swssss 10.1.154.10=>Host2
assas 10.1.154.14=>Host3
Expected Output
dhhdhja sasa 10.1.154.6=>Host1
sasas swssss 10.1.154.10=>Host2
assas 10.1.154.14=>Host3
10.1.154.34
10.1.154.38
Code
$log = "C:\Users\IP_Address.txt"
$DB=#()
$DB = Get-Content C:\Users\Hostname.txt
Get-Content $log |
Where-Object {$_ -match '(?<IP>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})'} |
ForEach-Object {
# Try to resolve the IP
Try
{
$IP = $Matches.IP
foreach($DBE in $DB)
{
if($IP -match $DBE.split("=>")[0])
{
$hostname = $DBE
if ($hostname -ne "")
{
Get-Content $log |
Where-Object {$_ -match $IP} |
ForEach-Object {
$_ -replace $IP, $hostname
}
}
}
}
}
catch
{
#$_ -replace $IP, $IP
}
}

Answer 1

Finally I was able to solve it..
Code:
$log = "C:\Users\IP_Address.txt"
$DB=#()
$DB = Get-Content "C:\Users\Hostname.txt"
$file = Get-Content "C:\Users\Hostname.txt"
Get-Content $log |
Where-Object {$_ -match '(?<IP>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})'} |
ForEach-Object {
$IP = $Matches.IP
$containsWord = $file | %{$_ -match $IP}
If($containsWord -contains $true)
{
# Try to resolve the IP
$IP = $Matches.IP
foreach($DBE in $DB)
{
if($IP -match$DBE.split("=>")[0])
{
$hostname = $DBE
if ($hostname -ne "")
{
Get-Content $log |
Where-Object {$_ -match $IP} |
ForEach-Object {
$_ -replace $IP, $hostname
}
}
}
}
}
Else{$_}
}

Answer 2

Try this:
$log = "C:\Users\IP_Address.txt"
$DB=#()
$DB = Get-Content C:\Users\Hostname.txt
## Loop through each line in IP_Address.txt to do the replacement, as needed
Get-Content $log | ForEach-Object {
## Perform work if we run into a line with an IP
if ($_ -match '(?<IP>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})') {
$DBE = $DB | ? { $_ -like "$($_)*" }
## Make sure the entry we get back is a valid IP
if ($DBE -match '(?<IP>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})') {
$_.Replace($_, $DBE) ## Replace just the IP with the IP/hostname from hostname.txt
} else {
$_ ## Else just emit the line as-is which still contains the original IP
}
} else {
$_
}
}