The password field may not be filled if shadow passwords have been enabled. If shadow passwords are being used, the encrypted password will be found in /etc/shadow. The encryped password consists of 13 characters from the 64 character alphabet a thru z, A thru Z, 0 thru 9, . and /. Refer to crypt(3) for details on how this string is interpreted.
An optional password age string may follow the encrypted password, separated by a comma, from the same alphabet as the password itself. The first character gives the number of weeks during which the password is valid. The second character gives the number of weeks which must pass before the user is permitted to change the password. The last two characters give the week since Jan 1970 when the password was last changed. When the number of weeks during which the password is valid have passed, the user will be required to provide a new password.
The comment field is used by various system utilities, such as finger(1). Three additional values may be present in the comment field. They are
These fields are separated from each other and from any other comment field by a comma.
The home directory field provides the name of the initial working directory. Login uses this information to set the value of the HOME environmental variable.
The command interpreter field provides the name of the user's command language interpreter, or the name of the initial program to execute. Login uses this information to set the value of the SHELL environmental variable. If this field is empty, it defaults to the value /bin/sh.