am start

read-only

Starts an activity by component or by intent — the fastest way to test whether a deep link resolves.

Command: adb shell am start
Commands: Activities and intents (am)
Risk: read-only

Syntax

am start [-W] [-a <action>] [-d <data URI>] [-n <package>/<activity>] [<extras>]

Flags and arguments

Token	Meaning
-W	Wait for the launch to complete and print its status and timings.
-a <action>	The intent action, e.g. `android.intent.action.VIEW`.
-d <uri>	The intent data URI. A scheme is required: without one there is nothing to match an intent filter against.
-n <pkg>/<activity>	Start one exact component, bypassing intent resolution.

Examples

am start -W -a android.intent.action.VIEW -d 'myapp://item/42'

Test a deep link and see which activity claimed it.

am start -W -a android.intent.action.VIEW -d 'https://example.com/item/42'

Test an App Link, including whether the browser wins instead of your app.

```
am start -n com.example/.MainActivity
```
Launch one activity directly, no intent filter involved.

Reading the output

Sample output

Starting: Intent { act=android.intent.action.VIEW dat=https://example.com/ flg=0x10000000 }
Status: ok
LaunchState: COLD
Activity: com.example/.MainActivity
TotalTime: 245
WaitTime: 262
Complete

With `-W` you get the intent as the platform parsed it, then the outcome. The interesting failures are not status lines at all: `Error: Activity not started, unable to resolve Intent { … }` is what an unclaimed scheme looks like, and `Warning: Activity not started, its current task has been brought to the front` is a success with a caveat — the app was already open, so nothing was cold-started and no timings are printed.

Output fields

Field	Meaning
Status: ok	An activity was started.
LaunchState	COLD, WARM or HOT — how much of the app was already alive.
Activity	The component that won the intent.
TotalTime	Milliseconds to the activity being drawn. Absent when nothing was launched.
WaitTime	Milliseconds including the time the caller was blocked.
Error: … unable to resolve Intent	Nothing on the phone claims that intent. Often the answer you were testing for.

Version and vendor notes

Single-quote the URI. A URL legitimately contains `&`, and an unquoted ampersand backgrounds the command and silently drops the rest of the query string — the classic reason a hand-typed deep-link test appears not to work.
`-d` without a scheme starts nothing: the intent's data cannot be built, and no filter can match it.
Timings are printed only for a real launch, so their absence is a fact about the launch rather than a 0 ms result.

We have a UI for this

Android ADB Toolbox runs this command over USB and parses what comes back — a Chromium browser, no SDK, nothing uploaded.

Open Android ADB Toolbox

Related commands

Commands that turn up in the same session as am start.

Command	What it does
am broadcast	Sends a broadcast intent, which is how SystemUI demo mode and other platform receivers are driven from a shell.
am force-stop	Kills every process and service belonging to one app.
dumpsys activity activities	Which app is in the foreground, and the task and stack structure behind it.

Checked against AOSP, toybox and kernel sources while writing the parsers behind our Web ADB tools. Where a behaviour genuinely varies by Android version or manufacturer, this page says so instead of giving a number that would be wrong on half the phones out there.

Frequently asked questions

How do I run an adb shell command?

Switch on developer options and USB debugging on the phone, plug it in, then run `adb shell <command>` from a machine with platform-tools installed — or run `adb shell` on its own to get an interactive prompt and type the command without the prefix. If the command produces binary output, such as a screenshot, use `adb exec-out` instead of `adb shell`: the plain shell service attaches a terminal, which rewrites newline bytes and corrupts the data.

Do adb shell commands need root?

Not the ones on this reference. They run as the `shell` user, which can manage packages for its own Android user, read most `dumpsys` services, write the settings provider, inject input and read shared storage. Root is only needed for things this reference deliberately avoids — reading another app's private data (except through `run-as` on a debuggable build), writing system partitions, or reading `/data/anr` directly.

Why does the output look different on my phone?

Either the Android version or the manufacturer. Some flags and fields arrived in a specific release, and those are noted per command. The rest is OEM patching, which hits `dumpsys` hardest: a dump is debug output whose text is whatever the service author last printed, and manufacturers change it and backport their changes. Read fields by name rather than by position, and treat an unfamiliar shape as a difference rather than as a failure.

Can I run this from a browser instead of a terminal?

For many commands, yes — the Web ADB tools on this site talk to a phone over WebUSB from a Chromium-based desktop browser, with no SDK installed and nothing uploaded. Each page links to the tool that runs its command, when one exists. Two limits are worth knowing: only one program can hold the ADB interface at a time, so a desktop `adb server` has to be stopped first, and `adb forward` and `adb reverse` cannot work in a browser at all.

Would rather click than type? The Web ADB Toolkit runs commands like this from a browser over USB. Or browse every command.