方法：adb shell pm dump packages > Desktop/log2.txt

包名為"android"的apk屬於平臺apk，肯定是系統簽名（平臺簽名），首先看一下包名為"android"的apk的簽名信息：

 Package [android] (ad28bfa):
    userId=1000
    sharedUser=SharedUserSetting{769a3df android.uid.system/1000}
    pkg=Package{6103b22 android}
    codePath=/system/framework/framework-res.apk
    resourcePath=/system/framework/framework-res.apk
    legacyNativeLibraryDir=/system/lib64/framework-res
    primaryCpuAbi=arm64-v8a
    secondaryCpuAbi=null
    versionCode=30 minSdk=30 targetSdk=30
    versionName=11
    splits=[base]
    apkSigningVersion=3
    applicationInfo=ApplicationInfo{6103b22 android}
    flags=[ SYSTEM PERSISTENT ALLOW_BACKUP ]
    privateFlags=[ PRIVATE_FLAG_ACTIVITIES_RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION ALLOW_AUDIO_PLAYBACK_CAPTURE DEFAULT_TO_DEVICE_PROTECTED_STORAGE DIRECT_BOOT_AWARE PRIVILEGED PRIVATE_FLAG_ALLOW_NATIVE_HEAP_POINTER_TAGGING ]
    forceQueryable=true
    queriesPackages=[]
    dataDir=/data/system
    supportsScreens=[small, medium, large, xlarge, resizeable, anyDensity]
    timeStamp=2021-07-12 23:27:41
    firstInstallTime=2021-07-12 23:27:41
    lastUpdateTime=2021-07-12 23:27:41
    signatures=PackageSignatures{539b9b3 version:3, signatures:[a0521abc
 
], past signatures:[]}
    installPermissionsFixed=true
    pkgFlags=[ SYSTEM PERSISTENT ALLOW_BACKUP ]
    declared permissions:
      android.permission.READ_CONTACTS: prot=dangerous, INSTALLED
      android.permission.WRITE_CONTACTS: prot=dangerous, INSTALLED
      ........

    User 0: ceDataInode=4316 installed=true hidden=false suspended=false distractionFlags=0 stopped=false notLaunched=false enabled=0 instant=false virtual=false
    overlay paths:
      /product/overlay/NavigationBarModeGestural/NavigationBarModeGesturalOverlay.apk
      

從上面資訊可以看到，簽名信息：signatures:[a0521abc] ，然後在log2.txt 檔案全域性搜尋“a0521abc”，可以列出所有系統簽名的應用