dex

Execute all programs in the autostart folders

$ dex [[-a|--autostart]]

$ dex [[-a|--autostart]] [[-s|--search-paths]] [path/to/directory1]:[path/to/directory2]:[path/to/directory3]:

$ dex [[-a|--autostart]] [[-e|--environment]] [GNOME]

$ dex [[-a|--autostart]] [[-d|--dry-run]]

$ dex [[-p|--property]] [Name] [path/to/file.desktop]

$ dex [[-c|--create]] [path/to/file.desktop]

$ dex --term [terminal] [path/to/file.desktop]

There is no single, standard 'dex' command for general purpose decompilation or manipulation readily available in most Linux distributions. Instead, operations on .dex files are performed by specific third-party utilities. Common examples include:

baksmali (for disassembly to Smali code):
baksmali [options] <input_dex_file>

dex2jar (for converting .dex to .jar):
dex2jar [options] <input_dex_file>

These tools have their own distinct syntax and options, which vary widely depending on their specific function.

-o <dir>
    Specifies the output directory for the disassembled Smali files. For example, -o ./output/. (Common to baksmali)

-d <file>
    Deodexes the input .dex file. Useful for files that have been optimized for a specific device. (Common to baksmali)

-b <bootclasspath_jar_or_dir>
    Specifies the bootclasspath to use for analysis, typically Android framework JARs. Can be a directory containing multiple JARs. (Common to baksmali)

-l <api_level>
    Sets the API level to use for instruction set features. For example, -l 28 for Android 9.0 (Pie). (Common to baksmali)

-f
    Forces overwrite of existing output files. (Common to dex2jar)

-h, --help
    Displays help message and exit. (Common to most command-line tools)

The term 'dex' in the context of Linux commands primarily refers to the Dalvik EXecutable file format used by Android applications. These files contain bytecode compiled for the Dalvik virtual machine (and later ART runtime), which executes Android apps on devices. Unlike common Linux utilities like `ls` or `grep`, there isn't a universally recognized, standalone 'dex' command in standard Linux distributions that directly performs decompilation.

Instead, interaction with .dex files for reverse engineering or analysis is typically done using various specialized third-party tools. These tools aim to convert the Dalvik bytecode into a more human-readable format, such as Smali assembly code (via tools like baksmali) or Java bytecode (via tools like dex2jar), which can then be decompiled further into Java source code.

The .dex format is central to Android app execution, and understanding its structure and how to process it is crucial for Android security researchers, malware analysts, and developers performing introspection or debugging on compiled applications.

The most significant caveat is the absence of a universally recognized 'dex' command for direct decompilation. Users often mistakenly refer to the file format when discussing commands. Tools for .dex file manipulation are generally developed by third parties, and their installation and usage may require specific knowledge of Android development environments or Java toolchains. Furthermore, reverse engineering compiled software may have legal and ethical implications depending on the jurisdiction and the software's licensing.

It is crucial to differentiate between the .dex file format itself and a command named 'dex'. While the .dex format is fundamental to Android applications, a general-purpose Linux command explicitly named 'dex' for decompilation is not part of standard Linux distributions or common Android development toolchains. Users wishing to decompile or analyze .dex files should seek out specific tools like baksmali, dex2jar, or jadx.

Processing .dex files is vital for:

• Security Analysis: Identifying vulnerabilities or malicious code in Android applications.
• Malware Research: Understanding the behavior of Android malware.
• Interoperability & Porting: Analyzing how proprietary apps function.
• Learning & Education: Studying how Android applications are built and how specific features are implemented at a lower level.
• Debugging & Reverse Engineering: When source code is unavailable, to understand or modify application behavior.

The Dalvik EXecutable (.dex) format originated with Google's Android operating system, first released in 2008. It was designed to be compact and efficient for mobile devices, using a register-based virtual machine called Dalvik. With Android 5.0 (Lollipop) and later, the Dalvik VM was largely replaced by the Android Runtime (ART), which uses Ahead-Of-Time (AOT) compilation but still consumes .dex files as its primary input.

The need for tools to understand and reverse engineer .dex files arose early in Android's history for various purposes, including security analysis, debugging, and malware research. Projects like baksmali and smali (for assembly/disassembly of Dalvik bytecode) and dex2jar (for converting .dex to Java JARs) emerged as essential utilities for this ecosystem, continually evolving to support new Android versions and bytecode features.

baksmali(1), smali(1), dex2jar, jadx, apktool, dx (Android SDK), d8 (Android SDK)