How to get output from ExecDos::exec

Question

When I execute netstat -a |find /C $portNumber in command prompt I get the total number of lines where the given port number exists.

I want to get that same count in any variable so that I can check whether the port is already occupied or free in NSIS.

I am excuting the below command and I tried in many ways, but I'm not able to get the output of the ExecDos::exec in a variable or in the stack.

ExecDos::exec "netstat -a |find /C '$portNumber'| $output"

Answer 1

To enable shell behavior you have to execute cmd.exe /C yourcommand (Or expand %ComSpec% with ExpandEnvStrings but hardcoding cmd.exe is ok if you don't support Win9x)

Or you can try the ExecCmd plug-in which does this for you (But it has fewer options so you would have to redirect the output to a file)

nsExec::ExecToStack with the cmd prefix should also work...

Edit:

Here is a working example (I used nsExec since it part of the default install)

!include LogicLib.nsh
section
ExpandEnvStrings $0 %COMSPEC%
StrCpy $1 445 ;Port number
nsExec::ExecToStack '"$0" /C netstat -an|find /C ":$1"'
Pop $0
${If} $0 = 0
    Pop $0
    MessageBox mb_ok "Port count=$0"
${Else}
    ; Port not open...
${EndIf}
sectionend