PASSWD(5) File Formats and Conversions PASSWD(5)
passwd - the password file
/etc/passwd contains one line for each user account, with seven fields
delimited by colons (":"). These fields are:
+o login name
+o optional encrypted password
+o numerical user ID
+o numerical group ID
+o user name or comment field
+o user home directory
+o optional user command interpreter
The encrypted password field may be blank, in which case no password is
required to authenticate as the specified login name. However, some
applications which read the /etc/passwd file may decide not to permit any
access at all if the password field is blank. If the password field is a
lower-case "x", then the encrypted password is actually stored in the
shadow(5) file instead; there must be a corresponding line in the /etc/shadow
file, or else the user account is invalid. If the password field is any other
string, then it will be treated as an encrypted password, as specified by
crypt(3).
The comment field is used by various system utilities, such as finger(1).
The home directory field provides the name of the initial working directory.
The login program 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. The login program
uses this information to set the value of the $SHELL environmental variable.
If this field is empty, it defaults to the value /bin/sh.
/etc/passwd
User account information.
/etc/shadow
optional encrypted password file
getent(1), login(1), passwd(1), su(1), crypt(3), getpwnam(3),
shadow(5), pwconv(8), pwunconv(8), sulogin(8).
File Formats and Conversions 07/30/2006 PASSWD(5)