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 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.

dumpsys diskstats

read-only

Free space per partition, a disk write latency check, and a cached per-app breakdown of what is using storage.

Command: adb shell dumpsys diskstats
Commands: System services (dumpsys)
Risk: read-only

Syntax

dumpsys diskstats

Examples

```
dumpsys diskstats
```
Everything the service has, live half and cached half.
```
df -k /data
```
A second, independent free-space reading for the partition that matters.

Reading the output

Sample output

Latency: 3ms [512B Data Write]
Data-Free: 12345678K / 111222333K total = 11% free
Cache-Free: 1234K / 5678K total = 21% free
App Size: 45678901234
App Data Size: 23456789012
App Cache Size: 3456789012

Two unrelated halves in one dump. The live half — the write latency and the `*-Free:` lines — is measured on every call, and its `K` suffix is KiB, so multiply by 1024 for bytes. The cached half comes from a file that a background job refreshes roughly daily, and its sizes are plain bytes despite what a similarly-named field elsewhere suggests. If the job has never run, the whole cached half is simply absent.

Output fields

Field	Meaning
Latency: Nms [512B Data Write]	How long a 512-byte write to /data took, measured now.
<partition>-Free: aK / bK total = c% free	Free and total space in KiB, plus the device's own integer-division percentage.
<partition>-Error: …	That partition could not be measured. The rest of the dump is still good.
App Size / App Data Size / App Cache Size	Aggregate code, data and cache totals, in bytes, from the cached half.
Package Names / App Sizes / App Data Sizes / Cache Sizes	Four parallel arrays that line up only by index.

What access it needs

This dump asks for two permissions, not one: `DiskStatsService.dump` opens with `DumpUtils.checkDumpAndUsageStatsPermission`, which wants `android.permission.DUMP` **and** `android.permission.PACKAGE_USAGE_STATS` plus the matching `android:get_usage_stats` app-op. Shell clears both without ceremony — its manifest declares both permissions, and the usage-stats check short-circuits `ROOT_UID`, `SYSTEM_UID`, `SHELL_UID` and `INCIDENTD_UID` before the app-op is even consulted. So no root, no `adb root`, and in particular no visit to the "Usage access" screen in Settings, which is the grant people go looking for when they see the permission name. What this command does need, and no other read on this page does, is a writable `/data`. The latency figure is not a statistic the service kept: `dump` creates `/data/system/perftest.tmp`, writes 512 non-zero bytes, closes it and deletes it, timing the write with `SystemClock.uptimeMillis()` on each call. That makes the safest-looking dump in the family the one that touches the filesystem every time you run it, and it is the reason this call can block behind a busy disk while `df` returns instantly. The Android Storage Analyzer sends it once per scan rather than on a timer for that reason.

Failure messages, decoded

Message	Meaning
Test-Error: java.io.IOException: /data/system/perftest.tmp: open failed: EACCES (Permission denied)	The 512-byte benchmark write failed, so this line replaces the `Latency:` line entirely rather than appearing beside it. Nothing else in the dump is affected: the free-space lines and the cached per-app half still follow and are still trustworthy. Only the write-latency measurement is gone.
Data-Error: java.lang.IllegalArgumentException: Invalid stat: bsize=0 avail=0 total=0	`reportFreeSpace` could not stat that partition and printed the exception where the numbers belong, then returned — for that partition only. The same line shape can appear as `Cache-Error`, `System-Error` or `Metadata-Error`. A missing `Metadata-Free:` line is usually age rather than a fault: no metadata partition is reported at all at tags android-11.0.0_r1 or android-12.0.0_r1, and it appears from android-13.0.0_r1 onward.
Recent Disk Write Speed data unavailable	`storaged` answered the request for its recent write-speed benchmark with zero, so the service printed this instead of a `Recent Disk Write Speed (kB/s) = …` line. It means nobody has benchmarked recently, not that the disk is slow. If `storaged` cannot be reached at all you get the raw exception text on its own line here instead.
Permission Denial: can't dump DiskStatsService from from pid=4821, uid=10231 due to missing android.permission.PACKAGE_USAGE_STATS permission	The second of the two permissions is the one that failed. As with every `DumpUtils` refusal the doubled `from from` is genuine AOSP text and the line is written to stdout, so it lands where the storage numbers would have been. Seeing this from an `adb shell` prompt means the call did not come from uid 2000 — check whether you are inside `run-as`.

Version and vendor notes

The per-app figures are not records, they are four separate arrays. If one is shorter than the others, every row after the gap is attributed to the wrong app — so if the four lengths disagree, the table is worthless and should be discarded rather than zipped.
This is one of the dumps that genuinely fails: it does a synchronous disk write and a binder round-trip, so it can hit the dumpsys timeout, and some builds refuse it outright on permission grounds.
The cached half is up to a day old. For a number you can trust right now, use `df` or `du`.

We have a UI for this

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

Open Android Storage Analyzer

Related commands

Commands that turn up in the same session as dumpsys diskstats.

Command	What it does
df	Reports free and used space per mounted filesystem.
du	Reports how much disk space a directory tree occupies.
pm trim-caches	Asks the system to drop cached files until the given amount of free space exists.
find	Walks a directory tree and prints what matches — big files, empty folders, leftovers.

More System services (dumpsys) commands

Command	What it does
dumpsys battery	The battery service's live state: level, status, health, voltage and temperature.
dumpsys thermalservice	Whether the phone is throttling, and every thermal zone the hardware layer reports, in degrees Celsius.
dumpsys sensorservice	Every sensor the phone has, with its vendor, type, rates and batching — plus a buffer of recent readings.
dumpsys meminfo	Which processes are using the most memory, measured as proportional set size.
dumpsys package	Everything the package manager knows about one app: version, paths, flags, install source and per-user state.
dumpsys activity activities	Which app is in the foreground, and the task and stack structure behind it.
dumpsys dropbox	The platform's ring buffer of crashes, ANRs and tombstones — how you read ANR traces without root.

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.