I have some predefined variables, eg:
$s1 = a
$s2 = b
...
$s[x] = x
I have a script that connects to a device via serial port, get some data, split the string and get a value I need.
The value that I have from the string I needed to use it to get a predefined variable.
In php I do it easily like this:
$var1 = a
$var2 = b
...
$var[x] = x
$i = something
echo ${"var_name$i"}
How can I do the same in PowerShell?
I tried
write-host $s$i
write-host $s{$i}
write-host ${s$i}
write-host ${"s$i"}
with no luck...all I get is either the value of $i or empty space
Use the Get-Variable cmdlet:
Write-Host $(Get-Variable "s$i" -ValueOnly)
You are looking for the Get-Variable cmdlet:
Get-Variable 'i'
Related
Curious about how to loop through a hash table where each value is an array. Example:
$test = #{
a = "a","1";
b = "b","2";
c = "c","3";
}
Then I would like to do something like:
foreach ($T in $test) {
write-output $T
}
Expected result would be something like:
name value
a a
b b
c c
a 1
b 2
c 3
That's not what currently happens and my use case is to basically pass a hash of parameters to a function in a loop. My approach might be all wrong, but figured I would ask and see if anyone's tried to do this?
Edit**
A bit more clarification. What I'm basically trying to do is pass a lot of array values into a function and loop through those in the hash table prior to passing to a nested function. Example:
First something like:
$parameters = import-csv .\NewComputers.csv
Then something like
$parameters | New-LabVM
Lab VM Code below:
function New-LabVM
{
[CmdletBinding()]
Param (
# Param1 help description
[Parameter(Mandatory=$true,
Position=0,
ValueFromPipeline=$true,
ValueFromPipelineByPropertyName=$true)]
[Alias("p1")]
[string[]]$ServerName,
# Param2 help description
[Parameter(Position = 1)]
[int[]]$RAM = 2GB,
# Param3 help description
[Parameter(Position=2)]
[int[]]$ServerHardDriveSize = 40gb,
# Parameter help description
[Parameter(Position=3)]
[int[]]$VMRootPath = "D:\VirtualMachines",
[Parameter(Position=4)]
[int[]]$NetworkSwitch = "VM Switch 1",
[Parameter(Position=4)]
[int[]]$ISO = "D:\ISO\Win2k12.ISO"
)
process
{
New-Item -Path $VMRootPath\$ServerName -ItemType Directory
$Arguments = #{
Name = $ServerName;
MemoryStartupBytes = $RAM;
NewVHDPath = "$VMRootPath\$ServerName\$ServerName.vhdx";
NewVHDSizeBytes = $ServerHardDriveSize
SwitchName = $NetworkSwitch;}
foreach ($Argument in $Arguments){
# Create Virtual Machines
New-VM #Arguments
# Configure Virtual Machines
Set-VMDvdDrive -VMName $ServerName -Path $ISO
Start-VM $ServerName
}
# Create Virtual Machines
New-VM #Arguments
}
}
What you're looking for is parameter splatting.
The most robust way to do that is via hashtables, so you must convert the custom-object instances output by Import-Csv to hashtables:
Import-Csv .\NewComputers.csv | ForEach-Object {
# Convert the custom object at hand to a hashtable.
$htParams = #{}
$_.psobject.properties | ForEach-Object { $htParams[$_.Name] = $_.Value }
# Pass the hashtable via splatting (#) to the target function.
New-LabVM #htParams
}
Note that since parameter binding via splatting is key-based (the hashtable keys are matched against the parameter names), it is fine to use a regular hashtable with its unpredictable key ordering (no need for an ordered hashtable ([ordered] #{ ... }) in this case).
Try this:
for($i=0;$i -lt $test.Count; $i++)
{$test.keys | %{write-host $test.$_[$i]}}
Weirdly, it outputs everything in the wrong order (because $test.keys outputs it backwards).
EDIT: Here's your solution.
Using the [System.Collections.Specialized.OrderedDictionary] type, you guarantee that the output will come out the same order as you entered it.
$test = [ordered] #{
a = "a","1";
b = "b","2";
c = "c","3";
}
After running the same solution code as before, you get exactly the output you wanted.
How can I force string variable expansion?
I need to read a string with one or more variable names in it (a template) and then expand it after I read the file. The key is that I must read the contents of the file before I declare the variables that will be used in the expansion. I've tried several ways but I can't get it to work.
It's not an option to read the file after $environment is defined.
Contents of name.txt:
$environment-RPT-INT
#example 1
$name = gc "c:\temp\name.txt"
$environment = "9065DEV"
$expanded = $ExecutionContext.InvokeCommand.ExpandString($name)
$expanded
#example 2
$name = gc "c:\temp\name.txt"
$environment = "9065DEV"
$expanded = $expanded = Invoke-Expression "`"$template`""
$expanded
#example 3
$name = gc "c:\temp\name.txt"
$environment = "9065DEV"
$name = $name.Clone()
$expanded = $ExecutionContext.InvokeCommand.ExpandString($name)
$expanded
Any help is appreciated.
Updated: Example 1 is now working for me.
It looks like you've found some possible solutions, but I'll suggest another that is in my opinion a bit smarter and more robust.
Instead of requiring variable names in your text file, why not use format specifiers. For example, the contents of name.txt:
{0}-RPT-INT
And in your script:
$name = gc "c:\temp\name.txt"
$environment = "9065DEV"
$expanded = $name -f $environment
$expanded
This way, you can rename the variable w/o changing any of your text files. As a bonus, if your text file comes from unknown sources, your script is vulnerable to code injection. For example, say you are given a text file with these contents:
$(rm -whatif -recurse -force c:\)-RPT-INT
Then ExpandString or Invoke-Expression will happily execute that code.
Your Invoke-Expression example is pretty close. Instead of using $template though, you need to use $name.
#example 2
$name = gc 'c:\temp\name.txt';
$environment = '9065DEV';
$expanded = Invoke-Expression -Command "`"$name`"";
$expanded;
If you are willing to store your Setting/Values in a CSV, I wrote a module to pull values from a CSV, put it into a HereString... any variables you put into the CSV become fully expanded inside the Here-String. That way, you can normally address the field names and values.
I might be able to change this to also work with traditional INI's if anyone is interested.
https://github.com/Inventologist?tab=repositories
Look for: HereStringFromCSV
There is a function called ExpandString predefined in powershell. It's inside $ExecutionContext, as follows.
$mystring = #'
This is a here string with some embedded variables.
Here is variable foo -- $foo
Here is variable bar -- $bar
Here is variable bletch -- $bletch
'#
#This displays the here string as is.
$mystring
#now define foo, bar and bletch
$foo = 5
$bar = Get-Date
$bletch = "George Washington"
#now run the here string through Expandstring.
$ExecutionContext.InvokeCommand.ExpandString($mystring)
I want to split one output. the output is
02|05|002|004|0014|0035|R
I tried with
$state.ToString().Split("|")[0]
i got the result like System.Object[]
i want to split the output and assigning to variables like
$a='02'
$b='05'
please help me to complete this
Here's a simplified solution that uses the range operator to return the first two elements and assign them to variables:
$a,$b = '02|05|002|004|0014|0035|R'.Split('|')[0..1]
Put them to the array using select -first
$state = '02|05|002|004|0014|0035|R'
$list = #()
$list = $state.ToString().Split("|") | select -First 2
[string] $a = $list[0]
[string] $b = $list[1]
write-host $a
write-host $b
I'm trying to alternate a setting in a config file using PowerShell. For example, if a certain value is true, I'd like to switch it to false. If it's false, I'd like to switch it to true. I'd also like to change a path from \\servername\folder\ to \\servername\. Is there a way I can perform this in PowerShell without using an intermediate value?
If I do this:
$foo = 'aaa'
$foo -replace 'aaa', 'bbb' -replace 'bbb', 'aaa'
$foo will always be 'aaa'. I realize I could make an intermittent change ('aaa' becomes 'ccc' and then changes to 'bbb') but that's messy to read.
How can I alternate values without using an intermediate value?
I'm not quite sure what you're trying to achieve. Do you want to switch two values without a buffer variable? Or do you want to toggle a value between two states? The latter can be achieved like this:
function Toggle($s, $v1, $v2) {
$e1 = [regex]::Escape($v1)
$e2 = [regex]::Escape($v2)
$r = $s
if ($s -match $e1) {
$r = $s -replace $e1, $v2
} elseif ($s -match $e2) {
$r = $s -replace $e2, $v1
}
return ($r)
}
$foo = "..."
Toggle $foo "\\servername\folder\" "\\servername\"
Using a match evaluator. Not sure if this is any better or not.
Begin{
[regex]$ValueRegex = 'aaa|bbb'
$ValueToggles = #{
aaa='bbb'
bbb='aaa'
}
$toggleValue = {$ValueToggles[$args[0].groups[0].value]}
}
Process{
$foo = 'Value: aaa'
$ValueRegex.replace($foo,$toggleValue)
}
Value: bbb
You can alternate a boolean value ($true or $false) simply by using the -not operator; e.g.:
PS C:\> $value = $true
PS C:\> $value = -not $value
PS C:\> $value
False
Regular expression replacement:
PS C:\> '\\servername\folder\' -replace '^(\\\\[^\\]+)\\[^\\]+', '$1'
\\servername\
Bill
I need to make a variable from the ID number of a username
qwinsta.exe /server:vm041 derpy.herp
This returns the following output
SESSIONNAME USERNAME ID STATE TYPE DEVICE
derpy.herp 3 Disc
I need to create a variable in powershell with a value of 3 as per output above.
This code will be used to look through a number of servers to see if an individual user is logged in and disconnect them with rwinsta.exe
Here's quite a crude regular expression - I don't know qwinsta.exe so I'm not sure of the permutations of data it can return - this works with your above example though.
This will assign 3 to the variable $ID.
$output = qwinsta.exe /server:vm041 derpy.herp
$output -match ".*derpy.herp.*(\d).*"
$ID = $Matches[1]
you may be able to parameterise the username like so:
$username = "derpy.herp"
$output = qwinsta.exe /server:vm041 $username
$output -match ".*$username.*(\d).*"
$ID = $Matches[1]
HTH,
Matt
You can parse the output you are obtaining, get your ID, and then use New-Variable cmdlet to instance your variable.