Does linux need to load the entire executable file?

Linux does not need to load the entire executable file, but uses a delayed loading method. Delayed loading means that during program execution, part of the executable file will only be loaded when needed. Loaded into memory, when a program is executed, the operating system loads the code and data of the executable file piece by piece as needed.

The operating system of this tutorial: Linux5.18.14 system, Dell G3 computer.

In the Linux system, when you want to execute an executable file, you do not need to load the entire executable file into the memory at once. Instead, Linux uses a lazy loading method.

Lazy loading means that during program execution, part of the executable file is loaded into memory only when needed. When a program is executed, the operating system loads the executable's code and data piece by piece as needed.

Specifically, the Linux system will load in segments according to the running requirements of the program:

• Code segment (Text Segment): contains the instructions and function codes of the program. When executing a program, the operating system loads code segments into memory on demand and sets relevant permissions, such as read-only permissions.

• Data Segment: Contains static data and global variables of the program. This data is usually initialized when the program starts, but does not need to be loaded into memory immediately. When a program accesses a piece of data for the first time, the operating system loads the corresponding data segment into memory.

• Heap: An area used to dynamically allocate memory. Memory allocation in the heap is performed through functions such as malloc(), and is dynamically increased as needed during the running of the program. Only when heap memory allocation is made, the operating system will load more heap space.

• Stack: used to store function calls, local variables and temporary data. The stack is dynamically allocated and released according to the nested order of function calls. The stack is loaded when the function is called, and the stack space is automatically released when the function returns.

By delaying loading, the Linux system can reduce memory usage and improve program startup speed. The corresponding code and data will only be loaded when really needed, saving memory resources. This loading method also provides better virtual memory management and page replacement mechanisms to optimize system performance.

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