Can I get && to work in Powershell?

问题:

&& is notoriously hard to search for on google, but the best I've found is this article which says to use -and.

Unfortunately it doesn't give any more information, and I can't find out what I'm supposed to do with -and (again, a notoriously hard thing to search for)

The context I'm trying to use it in is "execute cmd1, and if successful, execute cmd2", basically this:

csc /t:exe /out:a.exe SomeFile.cs && a.exe

This should be an easy few rep points to someone who knows, thanks!

---

Edit: If you just want to run multiple commands on a single line and you don't care if the first one fails or not, you can use ; For most of my purposes this is fine

For example: kill -n myapp; ./myapp.exe.

回答1:

In CMD, '&&' means "execute command 1, and if it succeeds, execute command 2". I have used it for things like:

build && run_tests

In PowerShell, the closest thing you can do is:

(build) -and (run_tests)

It has the same logic, but the output text from the commands is lost. Maybe it is good enough for you, though.

EDIT

If you're doing this in a script, you will probably be better off separating the statements, like this:

build
if ($?) {
    run_tests
}

回答2:

&& and || were on the list of things to implement (still are) but did not pop up as the next most useful thing to add. The reason is that we have -AND and -OR. If you think it is important, please file a suggestion on Connect and we'll consider it for V3.

回答3:

Try this:

$errorActionPreference='Stop'; csc /t:exe /out:a.exe SomeFile.cs; a.exe

回答4:

I tried this sequence of commands in PowerShell:

Fisrt Test

PS C:\> $MyVar = "C:\MyTxt.txt"
PS C:\> ($MyVar -ne $null) -and (Get-Content $MyVar)
True

($MyVar -ne $null) returned true and (Get-Content $MyVar) also returned true.

Second Test

PS C:\> $MyVar = $null
PS C:\> ($MyVar -ne $null) -and (Get-Content $MyVar)
False

($MyVar -ne $null) returned false and so far I must assume the (Get-Content $MyVar) also returned false.

Third test proved the second condition was not even analyzed.

PS C:\> ($MyVar -ne $null) -and (Get-Content "C:\MyTxt.txt")
False

($MyVar -ne $null) returned false and proved the second condition (Get-Content "C:\MyTxt.txt") never ran, by returning false on the whole command.

回答5:

If your command is available in cmd.exe (something like python ./script.py but not PowerShell command like ii . (This means to open the current directory by explorer)), you can run cmd.exe within PowerShell. The syntax is like this:

cmd /c "command1 && command2"

Here, && is provided by cmd syntax described in this question.

回答6:

I think a simple if statement can accomplish this. Once I saw mkelement0's response above that last exit status is stored in $?, I put the following together:

# Set 1st command to variable
$a=somecommand

# Temp var to store exit status of last command (since we can't write to $?)
$test=$?

# Run Test
if ($test=$true) { 2nd-command }

So for the op's example, it would be:

a=(csc /t:exe /out:a.exe SomeFile.cs); $test = $?; if ($test=$true) { a.exe }

回答7:

Typically, on Linux I'd do something like: ruby -c learn.rb && foodcritic learn.rb

However, on Windows PS, can't do it! So I ended up just making a .ps1 file with this:

Param(
  [string]$fileName
)

ruby -c $fileName
foodcritic $fileName

and called it bamemeril.ps1

PS C:\Users\riotc> .\bamemeril.ps1 learn.rb
Syntax OK
Checking 1 files
x
FC011: Missing README in markdown format: ../README.md:1
FC031: Cookbook without metadata.rb file: ../metadata.rb:1
FC071: Missing LICENSE file: ../LICENSE:1
PS C:\Users\riotc>

回答8:

A verbose equivalent is to combine $LASTEXITCODE and -eq 0:

msbuild.exe args; if ($LASTEXITCODE -eq 0) { echo 'it built'; } else { echo 'it failed'; }

I'm not sure why if ($?) didn't work for me, but this one did.

回答9:

It depends on the context, but here's an example of "-and" in action:

get-childitem | where-object { $_.Name.StartsWith("f") -and $_.Length -gt 10kb }

So that's getting all the files bigger than 10kb in a directory whose filename starts with "f".

回答10:

if (start-process filename1.exe) {} else {start-process filename2.exe}

It's a little longer than "&&" but accomplishes the same thing without scripting and is not too hard to remember. Better late than never. :)

回答11:

We can try this command instead of using && method

try {hostname; if ($lastexitcode -eq 0) {ipconfig /all | findstr /i bios}} catch {echo err} finally {}