Can any of you let me know how to state a variable in a PowerShell line? Just like I could do using PowerShell ISE I would like to be able to do so via the plain console.
You can assign values to a PowerShell variable by combining a variable name, an assignment operator, and an expression. Here is a simple example:
>> $a = 1 + 1
If you want to populate multiple variables with the same value, you can save some typing as in the example below:
>> $a = $b = $c = 1
You can also define multiple variables with different values on one line:
>> $a, $b, $c = 1, 2, 3
To display the value of a variable, you don’t need a special command as in many other programming languages; entering the variable name is enough. This works in a script and on a command prompt.
>> $c
To take values from user, similar to Python input() function you can use:
$Number = Read-Host "Please enter a number"
Read the official documentation here.
I finally found the solution to get the job done. I just set the variable and end it with a semi-colon. Then I can go on with scripting.
Thank you all.
Related
While using powershell I struggle to build up a filename from two variables. When I originally creaded the powershell script, it was working fine. Now I have tried to move some repeatable steps into a function, but the string behaviour is different.
MWE:
$topa = "ABC"
$topb = "XYZ"
function Test-Fun{
param(
$a,
$b
)
echo "$($a)H$($b).csv"
}
echo "$($topa)H$($topb).csv"
Test-Fun($topa, $topb)
The output on my system is
ABCHXYZ.csv
ABC XYZH.csv
Originally, I wanted to use an underscore instead of H and thought that is causing issues, but its not. What did I miss or rather what is the difference between string expansion within a function and outside of it?
You are calling Test-Func wrong. The comma after $topa will create an array, so you basically pass []"ABC", "XYZ" as an array to $a. In that case $b is empty!
You can easily fix this by removing the comma (also the parentheses are not necessary):
Test-Fun $topa $topb
I know I can dot source a file:
. .\MyFunctions.ps1
But, I would like to dot source the commands in a string variable:
. $myFuctions
I see that this is possible:
.{$x=2}
And $x equals 2 after the script block is sourced.
But... .{$myFunctions} does not work.
I tried $myFunctions | Invoke-Expression, but it doesn't keep the source function in the current scope. The closest I have been able to come up with is to write the variable to a temporary file, dot source the file, and then remove the file.
Inevitably, someone will ask: "What are you trying to do?" So here is my use case:
I want to obfuscate some functions I intend to call from another script. I don't want to obfuscate the master script, just my additional functions. I have a user base that will need to adjust the master script to their network, directory structure and other local factors, but I don't want certain functions modified. I would also like to protect the source code. So, an alternate question would be: What are some good ways to protect PowerShell script code?
I started with the idea that PowerShell will execute a Base64-encoded string, but only when passed on the command line with -EncodedCommand.
I first wanted to dot source an encoded command, but I couldn't figure that out. I then decided that it would be "obfuscated" enough for my purposes if I converted by Base64 file into a decode string and dot sourced the value of the string variable. However, without writing the decoded source to a file, I cannot figure out how to dot source it.
It would satisfy my needs if I could Import-Module -EncodedCommand .\MyEncodedFile.dat
Actually, there is a way to achieve that and you were almost there.
First, as you already stated, the source or dot operator works either by providing a path (as string) or a script block. See also: . (source or dot operator).
So, when trying to dot-source a string variable, PowerShell thinks it is a path. But, thanks to the possibility of dot-sourcing script blocks, you could do the following:
# Make sure everything is properly escaped.
$MyFunctions = "function Test-DotSourcing { Write-Host `"Worked`" }"
. { Invoke-Expression $MyFunctions }
Test-DotSourcing
And you successfully dot-sourced your functions from a string variable!
Explanation:
With Invoke-Expression the string is evaluated and run in the child scope (script block).
Then with . the evaluated expressions are added to the current scope.
See also:
Invoke-Expression
About scopes
While #dwettstein's answer is a viable approach using Invoke-Expression to handle the fact that the function is stored as a string, there are other approaches that seem to achieve the same result below.
One thing I'm not crystal clear on is the scoping itself, Invoke-Expression doesn't create a new scope so there isn't exactly a need to dot source at that point...
#Define your function as a string
PS> $MyUselessFunction = "function Test-WriteSomething { 'It works!' }"
#Invoke-Expression would let you use the function
PS> Invoke-Expression $MyUselessFunction
PS> Test-WriteSomething
It works!
#Dot sourcing works fine if you use a script block
PS> $ScriptBlock = [ScriptBlock]::Create($MyUselessFunction)
PS> . $ScriptBlock
PS> Test-WriteSomething
It works!
#Or just create the function as a script block initially
PS> $MyUselessFunction = {function Test-WriteSomething { 'It works!' }}
PS> . $MyUselessFunction
PS> Test-WriteSomething
It works!
In other words, there are probably a myriad of ways to get something similar to what you want - some of them documented, and some of them divined from the existing documentation. If your functions are defined as strings, then Invoke-Expression might be needed, or you can convert them into script blocks and dot source them.
At this time it is not possible to dot source a string variable.
I stand corrected! . { Invoke-Expression $MyFunctions } definitely works!
I've been searching all over the place and since I'm taking my first steps in PERL this might be one of he dumbest questions but here it goes.
So I'm creating a script to manage my windows and later bind it to keyboard shortcuts, so I I'm trying to run a command and passing some variables:
my $command = `wmctrl -r :ACTIVE: -e 0,0,0,$monitors->{1}->{'width'}/2,$monitors->{1}->{'height'}`;
But I get an error saying I'm not passing the right parameters to the command, but if I do this, everything works great:
my $test = $monitors->{1}->{'width'}/2;
my $command = `wmctrl -r :ACTIVE: -e 0,0,0,$test,$monitors->{1}->{'height'}`;
So do I really have to do this? assign it first to a variable and then pass it, or there's a more elegant way of doing it?
The backticks operator (or the qx{}) accepts A string which is (possibly) interpolated. So accepts string and not expression like $var/2.
Thats mean than the $variables ($var->{1}->{some} too) are expanded but not the arithmetic expressions.
Therefore your 2 step variant works, but not the first.
If you want evaluate an expression inside the string you can use the next:
my $ans=42;
print "The #{[ $ans/2 ]} is only the half of answer\n";
prints
The 21 is only the half of answer
but it is not very readable, so better and elegant is what you're already doing - calculate the command argument in andvace, and to the qx{} or backticks only pass the calculated $variables.
I have a Perl script that invokes an Expect script with command line arguments passed to it.
I wanted to know if we pass an array variable as argument, how do we retrieve the array variable in expect script?
For a simple variable passed as command line argument : set var [lindex $argv 0] is used.
I need to know how to access array variable in similar fashion and use its elements in the expect script. a sample code would be of great help!
looking forward for responses,
Thank you.
The expect global variable $argv is a list (i.e. a perl array). If you want to capture it in a different variable:
set myvar $argv
Or use it directly
foreach item $argv {
do something with $item
}
how do you define a variable to an integer at the command line. For example if i want to assign A=22 and B=23 and then have the A and B = a separate variable such as C..? I am confused on the syntax of this at the command line. I understand how to set variables in a script but how would i do it from a command line using only 1 line?
A=22; B=23; ((C=A+B)); echo $A $B $C
Assuming Bash or Korn shell.
set A=22
set B=23
set A=%C%
set B=%C%
In windows bat-files. Also be careful not to use any extra spaces in batch file syntax. It can screw up everything.