unable to generate the hash for netbeans 8.2

Question

I am unable to generate the hash for the netbeans 8.2 for Ubuntu 16.04 after I write the command:

ravi@Dell:~/Downloads$ sha256 netbeans-8.2-linux.sh 
mlockall: Cannot allocate memory
Warning: couldn't lock memory, are you root?
Enter passphrase: 

Now what is this passphrase?
What should I do now?

Answer 1

I suspect that you should have execute sha256sum which calculate the checksum.

sha256sum netbeans-8.2-linux.sh 

I also found NetBeans 8.2 C / C ++ for Linux Xubuntu 16.04 64/32 which specify:

and check its sha256 (from Terminal: sha256sum path / filename).

---

See below the difference between sha256 and sha256sum

man sha256sum - compute and check SHA256 message digest
man sha256 - hashalot - read a passphrase and print a hash

Answer 2

From man sha256 passphrase is just used to produce the hashing any thing is fine.

DESCRIPTION
       hashalot is a small tool that reads a passphrase from standard input, hashes it using the given hash type, and
       prints the result to standard output.

       Warning: If you do not use the -x option, the hash is printed in binary. This may  wedge  your  terminal  set‐
       tings, or even force you to log out.

       This  is  not  a  general  purpose  hasher, only the first line is used, not even including the final newline.
       Thus, don't be surprised if the output seems to be different from other tools -- you'd have  to  hash  exactly
       the same string.

Answer 3

it hashes from std in, so perhaps this would work:

cat netbeans-8.2-linux.sh  |sha256

However, you have another issue there, you must set the the memory allocation, to get rid of the mlockall error.