DESTDIRbuildroot

DESTDIR is a common variable used in build systems, particularly in projects like Buildroot, to specify a destination directory for installed files. When a package is compiled and installed, the `DESTDIR` variable acts as a prefix for the installation path. This is crucial for cross-compilation environments where the target system's root filesystem is being built on a host system.

In Buildroot, `DESTDIR` is primarily used during the `make install` phase of package building. It allows Buildroot to install the compiled files into a temporary staging area, which is separate from the host system's actual filesystem and also separate from the final target root filesystem. This staging area is often referred to as the "staging directory."

The purpose of `DESTDIR` is to enable flexible installation strategies. Instead of directly installing files into the final target root filesystem, which could interfere with the host system or other build processes, `DESTDIR` facilitates an intermediate step. After all packages are installed into the `DESTDIR`, Buildroot can then copy or move the contents of this directory to the final target root filesystem image. This separation helps maintain a clean build environment and prevents unintended modifications to the host system. It is a fundamental mechanism for organizing the output of a build process and preparing it for deployment on a different system.

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