How to fix C error: undefined reference to MD5_Update

When linking against OpenSSL, you may see:

md5_link_error.txt

undefined reference to `MD5_Update'

undefined reference to `MD5_Update'

Ensure you link against the correct OpenSSL libraries, e.g.:

gcc_openssl_example.sh

gcc -o myprog myprog.c -lcrypto

gcc -o myprog myprog.c -lcrypto

Or with pkg-config:

pkgconfig_openssl.sh

gcc -o myprog myprog.c $(pkg-config --cflags --libs openssl)

gcc -o myprog myprog.c $(pkg-config --cflags --libs openssl)

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