NSIS - Refresh rate of a monitor to a variable from a CMD command

This is how I get the refresh rate of my primary monitor, by typing this command in CMD:

wmic PATH Win32_videocontroller get currentrefreshrate

Result:

CurrentRefreshRate
144
75

The second line is the refresh rate of my primary monitor. I would like to have this number assigned to a variable called $refreshrate. How to achieve this?

You don't have to rely on external tools, you can ask the system directly:

For the entire screen:

!include LogicLib.nsh
Section
!define /IfNDef VREFRESH 116
System::Call USER32::GetDC(p0)p.r0
System::Call GDI32::GetDeviceCaps(pr0,i${VREFRESH})i.r1
System::Call USER32::ReleaseDC(p0,pr0)
${If} $1 < 5
    StrCpy $1 "Invalid"
${EndIf}
DetailPrint "Refresh rate=$1"
SectionEnd

Current display where the application (thread) is:

!include LogicLib.nsh
Section
!define /IfNDef ENUM_CURRENT_SETTINGS -1
!define /IfNDef DM_DISPLAYFREQUENCY 0x00400000

System::Call 'USER32::GetClientRect(p0,@r1)' ; Lazy allocation of a DEVMODE
System::Call '*$1(&i68,&i2 68)'
System::Call 'USER32::EnumDisplaySettingsW(p0, i${ENUM_CURRENT_SETTINGS}, pr1)i.r0'
System::Call '*$1(&i72,i.r2)'
${If} $0 <> 0
${AndIf} $2 & ${DM_DISPLAYFREQUENCY}
    System::Call '*$1(&i184,i.r3)'
    DetailPrint "Current display=$3"
${EndIf}
SectionEnd

Primary adapter:

!include LogicLib.nsh
Section
!define /IfNDef ENUM_CURRENT_SETTINGS -1
!define /IfNDef DM_DISPLAYFREQUENCY 0x00400000
!define /IfNDef DISPLAY_DEVICE_PRIMARY_DEVICE 4
System::Call 'USER32::GetClientRect(p0,@r1)' ; Lazy allocation of a DISPLAY_DEVICE 
StrCpy $4 0
loop:
System::Call '*$1(i840)'
System::Call 'USER32::EnumDisplayDevicesW(p0, ir4, pr1, i0)i.r0'
IntOp $4 $4 + 1
${If} $0 <> 0
    System::Call '*$1(i,&w32.r2,&w128,i.r3)'
    ${If} $3 & ${DISPLAY_DEVICE_PRIMARY_DEVICE}
        System::Call '*$1(&i68,&i2 68)' ; DEVMODE
        System::Call 'USER32::EnumDisplaySettingsW(wr2, i${ENUM_CURRENT_SETTINGS}, pr1)i.r0'
        System::Call '*$1(&i72,i.r2)'
        ${If} $0 <> 0
        ${AndIf} $2 & ${DM_DISPLAYFREQUENCY}
            System::Call '*$1(&i184,i.r3)'
            DetailPrint "Primary adapter=$3"
        ${EndIf}
    ${Else}
        Goto loop
    ${EndIf}
${EndIf}
SectionEnd

If you really really want to use WMI:

!include "StrFunc.nsh"  
${Using:StrFunc} StrRep 
!include LogicLib.nsh
Section
nsExec::ExecToStack '"wmic.exe" PATH Win32_videocontroller get  currentrefreshrate /all'
Pop $0
Pop $1
${StrRep} $1 $1 "currentrefreshrate" ""
loop:
    StrCpy $2 $1 1
    ${If} $2 == "$\r"
    ${OrIf} $2 == "$\n"
    ${OrIf} $2 == " "
        StrCpy $1 $1 "" 1
        Goto loop
    ${EndIf}
IntOp $2 $1 + 0 ; First number
${If} $0 = 0
    DetailPrint WMIC=$2
${EndIf}
SectionEnd