Usage: chpasswd [options]

Options:
  -c, --crypt-method METHOD     the crypt method (one of NONE DES MD5 SHA256 SHA512)
  -e, --encrypted               supplied passwords are encrypted
  -h, --help                    display this help message and exit
  -m, --md5                     encrypt the clear text password using
                                the MD5 algorithm
  -R, --root CHROOT_DIR         directory to chroot into
  -s, --sha-rounds              number of SHA rounds for the SHA*
                                crypt algorithms

# echo 'user01:password' | chpasswd

# echo 'user:hash-password' | chpasswd -e

# echo 'USER:PASS' > tmp.txt ; chpasswd < tmp.txt ; rm -f tmp.txt

# cat newpasswd.txt
user1:password123
user2:password456
user3:password789

# chpasswd < newpasswd.txt

# openssl passwd -1 'pass'      <- MD5 Only

# grub-crypt --md5
Password: 
Retype password: 

# grub-crypt --sha-256
Password: 
Retype password: 

# grub-crypt --sha-512
Password: 
Retype password: 

# openssl passwd -1 'newpassword'
$1$0u444IQv$YSGCzz8mesPzCWwxHCxit.

# echo 'user01:$1$0u444IQv$YSGCzz8mesPzCWwxHCxit.' | chpasswd -e
# cat /etc/shadow |grep test1
test1:$1$0u444IQv$YSGCzz8mesPzCWwxHCxit.:17526:0:99999:7:::
# exit
$ su - user01
            <- newpassword

password command uses MD5, but chpasswd command uses DES,
If you want to use MD5, you add below.

/etc/login.defs

MD5_CRYPT_ENAB yes