On some embedded linux systems, there is no /etc/passwd file and /etc directory is not writable (which means I cannot set user account and password?). Then what is my (default) account name and password, or how to set account and password? I need to get account and password on embedded linux to run ssh server, which requires user account and password for ssh login.
How to check my account on embedded linux without /etc/passwd?
linux;ssh;password;embedded;dropbear
If there is no /etc/passwd, then your embedded system is not running what is usually known as the Linux system, but rather a different operating system which is also based on the Linux kernel. A famous example of an operating system which uses on the Linux kernel but is not Linux is Android. Android doesn't have user accounts (at least not in its basic usage) and repurposes users to isolate applications rather than accounts.Such embedded systems are generally not meant to have user accounts. They have at most a control console, which is solely intended for administration and allows running commands as root. There may be authentication in some form, or the fact that you have physical access may be considered sufficient authentication. There's no general rule there, you have to know (or find out) how your system is designed.If you want to connect with SSH, you'll have to supply credentials to the SSH servers.