docker run --rm -v $(pwd):/data gcc:latest ar t /data/libmylib.a ar t lists the object files inside the archive. If you need to pull an object file from an existing static library:
CMD ["./myprogram"]
docker run --rm -v $(pwd):/data gcc:latest ar x /data/libmylib.a mylib.o FROM alpine:latest AS builder RUN apk add --no-cache gcc musl-dev make
Note: It’s likely you meant combined with ar (the Unix archive tool), or perhaps you are thinking of docker build with .a (static library) files, or docker + tar (since docker save produces a .tar archive). However, I’ll interpret docer ar as a typo for docker + ar usage — because ar is often used inside Docker builds to create static library archives for C/C++ apps inside containers. Using ar (GNU Archiver) Inside Docker Builds ar is a Unix utility that creates, modifies, and extracts from archives ( .a files — static libraries). It is commonly used in C/C++ development. Inside a Docker container, you can use ar to package object files into a static library that your application links against. 1. Minimal Dockerfile Using ar FROM gcc:latest WORKDIR /app Copy source code COPY mylib.c mylib.h main.c ./ Compile object file RUN gcc -c mylib.c -o mylib.o Create static library with ar RUN ar rcs libmylib.a mylib.o Compile main program and link with the static library RUN gcc main.c -L. -lmylib -o myprogram
If you actually meant docker + tar (e.g., docker save ), let me know and I can provide a similar guide for that.