[kbenson]

Well...

    CHECKPW="p@ssword" SHA1=`echo -n "$CHECKPW" | sha1sum`; curl -s https://api.pwnedpasswords.com/range/${SHA1:0:5} | grep -i ${SHA1:5:34}

[skykooler]

Note that this command doesn't work if your password contains an exclamation mark.