Converting a shell script to PowerShell - powershell

Question

After switching an application from Linux to Windows, I need to convert a shell script to a Windows equivalent. My choices were basically batch and PowerShell and I decided to give a shot to PowerShell.
For anyone interested, it's a local check for Check_MK to get information about SoftEther installed version and the number of sessions with performance data.
The initial shell script was as follow:
#!/bin/sh
cmd=$(/usr/local/vpnserver/vpncmd localhost:port /server /password:password /in:/usr/lib/check_mk_agent/local/vpncmd.txt)
version=$(echo "$cmd" | head -4 | tail -1)
sessions=$(echo "$cmd" | grep Sessions | awk '$1=$1' | cut -c21-22)
if [ -z "$version" ]; then
echo "3 VPN_Version - Can't get the information from vpncmd"
else
echo "0 VPN_Version - SoftEther VPN Server $version"
fi
if [ -z "$sessions" ]; then
echo "3 VPN_Sessions - Can't get the information from vpncmd"
else
echo "P VPN_Sessions sessions=$sessions;2;2"
fi
I basically got everything working except the 2 hardest lines of code:
cd "C:\Program Files\SoftEther VPN Server"
$cmd = vpncmd localhost:port /server /password:password /in:vpncmd.txt
$version=
$sessions=
if($version -eq $null) {
echo "3 VPN_Version - Can't get the information from vpncmd"
} else {
echo "0 VPN_Version - SoftEther VPN Server $version"
}
if($sessions -eq $null) {
echo "3 VPN_Sessions - Can't get the information from vpncmd"
} else {
echo "P VPN_Sessions sessions=$sessions;2;2"
}
I need help with going from the head, tail, grep, awk and cut one liners to whatever is equivalent in PowerShell. I read about Get-Content but I'm not sure if it's the most efficient way to do this and would like to prevent going from 1 line definition to 10 lines if that's possible to be as efficient in PowerShell.
Sample output of vpncmd's output: https://pastebin.com/J5FcHzHK

Answer 1

with the data being an array of lines & the word Version appearing multiple times in the actual source, the code needs to change a tad. in this version, it uses the way that -match works on an array to give the whole line as a result. that requires working on the output line to parse the desired data.
$Version = ($Vpncmd_Output -match '^Version \d{1,}\.\d{1,}' -split 'Version ' )[-1].Trim()
$SessionCount = [int]($Vpncmd_Output -match 'Number of Sessions\s+\|').Split('|')[-1].Trim()
$Version
$SessionCount
output ...
4.29 Build 9680 (English)
0
using the data in your PasteBin post, and presuming that is a multiline string, not an array of strings, this seems to work [grin] ...
$Vpncmd_Output -match '(?m)Number of Sessions\s+\|(?<Sessions>.*)'
$Matches.Sessions
# output = 0
$Vpncmd_Output -match '(?m)Version (?<Version>.+)'
$Matches.Version
# output = 4.29 Build 9680 (English)
i tried to combine the regex into one, but failed. [blush] the way i have it requires two passes, but it does work.