Is it possible to add a user in ubuntu linux without useradd command I think its possible by adding the entries in
/etc/passwd and /etc/shadow but i don't know the exact steps to do it and the user should get its home directory and bash shell too.
It's not recommended to manually modify
The shell will be
Usually, if you wish to add a user with the bash shell, thereby create a home directory
This command is basically determining a free User ID
..and thereby possibly making a backup of the files.
The next manual pages about the file formats may be of interest to you:
Although not usually necessary or recommended, the answer to the question of How to add user without useradd command is to use
This will launch your system-defined editor while locking the passwd file. Enter a line for a new user. (In vi, shift-G to get to the last line then yy p to duplicate it.) Edit the username and create a unique user ID number.
After saving the file and exiting the editor, you'll be prompted to edit /etc/shadow. Use the same technique to create a new line and use "*" for the password hash. The new account is locked. Use
It's also necessary to create a home directory, copy files from the skeleton directory, set group permissions, etc. But
Source: http://itguykelly.wordpress.com/2011/04/19/manually-add-new-user-to-red-hatfedoracentos/ (yes, these commands work across various flavors of *nix)