am，activity manager的缩写，用户通过am命令管理activity、service、broadcast，输出调试信息等，代码文件：
/frameworks/base/services/core/java/com/android/server/am/ActivityManagerShellCommand.java
方法onCommand的case语句包含相应am 命令参数，具体参数作用去搜索
@Override
public int onCommand(String cmd) {
if (cmd == null) {
return handleDefaultCommands(cmd);
}
final PrintWriter pw = getOutPrintWriter();
try {
switch (cmd) {
case "start":
case "start-activity":
return runStartActivity(pw);
case "startservice":
case "start-service":
return runStartService(pw, false);
case "startforegroundservice":
case "startfgservice":
case "start-foreground-service":
case "start-fg-service":
return runStartService(pw, true);
case "stopservice":
case "stop-service":
return runStopService(pw);
case "broadcast":
return runSendBroadcast(pw);
case "compact":
return runCompact(pw);
case "instrument":
getOutPrintWriter().println("Error: must be invoked through 'am instrument'.");
return -1;
case "trace-ipc":
return runTraceIpc(pw);
case "profile":
return runProfile(pw);
case "dumpheap":
return runDumpHeap(pw);
case "set-debug-app":
return runSetDebugApp(pw);
case "set-agent-app":
return runSetAgentApp(pw);
case "clear-debug-app":
return runClearDebugApp(pw);
case "set-watch-heap":
return runSetWatchHeap(pw);
case "clear-watch-heap":
return runClearWatchHeap(pw);
case "clear-exit-info":
return runClearExitInfo(pw);
case "bug-report":
return runBugReport(pw);
case "force-stop":
return runForceStop(pw);
case "stop-app":
return runStopApp(pw);
case "fgs-notification-rate-limit":
return runFgsNotificationRateLimit(pw);
case "crash":
return runCrash(pw);
case "kill":
return runKill(pw);
case "kill-all":
return runKillAll(pw);
case "make-uid-idle":
return runMakeIdle(pw);
case "monitor":
return runMonitor(pw);
case "watch-uids":
return runWatchUids(pw);
case "hang":
return runHang(pw);
case "restart":
return runRestart(pw);
case "idle-maintenance":
return runIdleMaintenance(pw);
case "screen-compat":
return runScreenCompat(pw);
case "package-importance":
return runPackageImportance(pw);
case "to-uri":
return runToUri(pw, 0);
case "to-intent-uri":
return runToUri(pw, Intent.URI_INTENT_SCHEME);
case "to-app-uri":
return runToUri(pw, Intent.URI_ANDROID_APP_SCHEME);
case "switch-user":
return runSwitchUser(pw);
case "get-current-user":
return runGetCurrentUser(pw);
case "start-user":
return runStartUser(pw);
case "unlock-user":
return runUnlockUser(pw);
case "stop-user":
return runStopUser(pw);
case "is-user-stopped":
return runIsUserStopped(pw);
case "get-started-user-state":
return runGetStartedUserState(pw);
case "track-associations":
return runTrackAssociations(pw);
case "untrack-associations":
return runUntrackAssociations(pw);
case "get-uid-state":
return getUidState(pw);
case "get-config":
return runGetConfig(pw);
case "suppress-resize-config-changes":
return runSuppressResizeConfigChanges(pw);
case "set-inactive":
return runSetInactive(pw);
case "get-inactive":
return runGetInactive(pw);
case "set-standby-bucket":
return runSetStandbyBucket(pw);
case "get-standby-bucket":
return runGetStandbyBucket(pw);
case "send-trim-memory":
return runSendTrimMemory(pw);
case "display":
return runDisplay(pw);
case "stack":
return runStack(pw);
case "task":
return runTask(pw);
case "write":
return runWrite(pw);
case "attach-agent":
return runAttachAgent(pw);
case "supports-multiwindow":
return runSupportsMultiwindow(pw);
case "supports-split-screen-multi-window":
return runSupportsSplitScreenMultiwindow(pw);
case "update-appinfo":
return runUpdateApplicationInfo(pw);
case "no-home-screen":
return runNoHomeScreen(pw);
case "wait-for-broadcast-idle":
return runWaitForBroadcastIdle(pw);
case "compat":
return runCompat(pw);
case "refresh-settings-cache":
return runRefreshSettingsCache();
case "memory-factor":
return runMemoryFactor(pw);
case "service-restart-backoff":
return runServiceRestartBackoff(pw);
case "get-isolated-pids":
return runGetIsolatedProcesses(pw);
case "set-stop-user-on-switch":
return runSetStopUserOnSwitch(pw);
case "set-bg-abusive-uids":
return runSetBgAbusiveUids(pw);
case "list-bg-exemptions-config":
return runListBgExemptionsConfig(pw);
default:
return handleDefaultCommands(cmd);
}
} catch (RemoteException e) {
pw.println("Remote exception: " + e);
}
return -1;
}