How to list all options that are supported by a specific OpenSSL command? I know the command but I don't remember the options for that command.

Interestingly, there is no "-h" option to show all options supported by a specific OpenSSL command.

However, if you enter "-h" as an option following a command, OpenSSL will return you an error message saying "bad option or value" with a list of valid options to help you to enter valid options as you see in the example below:

OpenSSL> speed -h

Error: bad option or value

Available values:
md2      md4      md5      hmac     sha1     sha256   sha512   rmd160
idea-cbc rc2-cbc  bf-cbc
des-cbc  des-ede3 aes-128-cbc aes-192-cbc aes-256-cbc aes-128-ige aes-192-ige
aes-256-ige rc4
rsa512   rsa1024  rsa2048  rsa4096
dsa512   dsa1024  dsa2048
ecdsap160 ecdsap192 ecdsap224 ecdsap256 ecdsap384 ecdsap521
ecdsak163 ecdsak233 ecdsak283 ecdsak409 ecdsak571
ecdsab163 ecdsab233 ecdsab283 ecdsab409 ecdsab571
ecdsa
ecdhp160  ecdhp192  ecdhp224  ecdhp256  ecdhp384  ecdhp521
ecdhk163  ecdhk233  ecdhk283  ecdhk409  ecdhk571
ecdhb163  ecdhb233  ecdhb283  ecdhb409  ecdhb571
ecdh
idea     rc2      des      aes      rsa      blowfish

Available options:
-engine e       use engine e, possibly a hardware device.
-evp e          use EVP e.
-decrypt        time decryption instead of encryption (only EVP).
-mr             produce machine readable output.
error in speed

So entering "<command> -h" is a way to list all options supported by this command.

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