Have a look at man 5 shadow and man 3 crypt. From the latter, you can learn that password hashes in /etc/shadow have the following form:
$id$salt$encrypted
where id defines the type of encryption and, reading further, can be one of
ID | Method
---------------------------------------------------------
1 | MD5
2a | Blowfish (not in mainline glibc; added in some
| Linux distributions)
5 | SHA-256 (since glibc 2.7)
6 | SHA-512 (since glibc 2.7)
Depending on the type of hash, you need to use the appropriate function/tool for generating and verifying the password "by hand".