How to set up git in NAS Server (git, ssh, busybox)
It appears that your are just typing the line into the shell, you need to edit the /etc/passwd file as it says (using vi or whatever editor you have installed) and add the line (assuming user):
vi /etc/passed
Go to the end of the file, hit shift-a to get to insert mode, hit Enter to start a new line, and paste the following:
user1:x:1026:100::/volume1/home/user1:/bin/sh
Then Esc Then save the file:
:wq