Makefile -将命令输出保存到变量？(SHA-256总和计算)

Question

我已经修改了这段代码，将其升级到SHA-256：

https://unix.stackexchange.com/questions/28994/how-can-a-makefile-detect-whether-a-command-is-available-in-the-local-machine

determine_sum = \
    sum=; \
    for x in sha256sum sha256 'shasum -a 256' 'openssl dgst -sha256'; do \
        if type "$${x%% *}" >/dev/null 2>/dev/null; then sum=$$x; break; fi; \
    done; \
    if [ -z "$$sum" ]; then echo 1>&2 "Unable to find a SHA-256 utility"; exit 2; fi

check:
    $(determine_sum); \
    $$sum $(archive_name); \
    #Save ^^^ to a variable - fails
    #archive_sha256=`$$sum $(archive_name)`; \

它正确地计算了一个SHA-256校验和--但是我在尝试将$$sum $(archive_name); \执行过程中看到的输出保存到一个变量时被卡住了。你能帮帮忙吗？

Answer 1

你有没有尝试：

check:
    $(determine_sum); \
    archive_sha256=$$($$sum $(archive_name)); \
    ...