Shell Programming and Scripting

Hi folks,

Can anyone of u expalin atleast one of the following contents of the file /etc/passwd

I just to want to know how to comprehend it ..say vat does : signify or :: or :/ ??

root:x:0:0:Super-User:/rthome:/sbin/sh
daemon:x:1:1::/:
bin:x:2:2::/usr/bin:
sys:x:3:3::/:
adm:x:4:4:Admin:/var/adm:
lp:x:71:8:Line Printer Admin:/usr/spool/lp:
uucp:x:5:5:uucp Admin:/usr/lib/uucp:
nuucp:x:9:9:uucp Admin:/var/spool/uucppublic:/usr/lib/uucp/uucico
smmsp:x:25:25:SendMail Message Submission Program:/:
listen:x:37:4:Network Admin:/usr/net/nls:
gdm:x:50:50:GDM Reserved UID:/:
webservd:x:80:80:WebServer Reserved UID:/:
nobody:x:60001:60001:NFS Anonymous Access User:/:
noaccess:x:60002:60002:No Access User:/:
nobody4:x:65534:65534:SunOS 4.x NFS Anonymous Access User:/:
operator:x:10:3:system backup acct:/operator:/sbin/sh
sshd::x:65533:65533:sshd privsep:/var/empty:/bin/false


Rajesh

An entry in the /etc/passwd file has the following form:

Name:Password: UserID:PrincipleGroup:Gecos: HomeDirectory:Shell

Attributes in an entry are separated by a : (colon). For this reason, you should not use a : (colon) in any attribute. The attributes are defined as follows:

Name Specifies the user's login name. The user name must be a unique string of 8 bytes or less. There are a number of restrictions on naming users. See the mkuser command for more information.

Password Contains an * (asterisk) indicating an invalid password or an ! (exclamation point) indicating that the password is in the /etc/security/passwd file. Under normal conditions, the field contains an !. If the field has an * and a password is required for user authentication, the user cannot log in.

UserID Specifies the user's unique numeric ID. This ID is used for discretionary access control. The value is a unique decimal integer.

PrincipleGroup Specifies the user's principal group ID. This must be the numeric ID of a group in the user database or a group defined by a network information service. The value is a unique decimal integer.

Gecos Specifies general information about the user that is not needed by the system, such as an office or phone number. The value is a character string. The Gecos field cannot contain a colon.

HomeDirectory Specifies the full path name of the user's home directory. If the user does not have a defined home directory, the home directory of the guest user is used. The value is a character string.

Shell Specifies the initial program or shell that is executed after a user invokes the login command or su command. If a user does not have a defined shell, /usr/bin/sh, the system shell, is used. The value is a character string that may contain arguments to pass to the initial program.

that information was really helpful

I could make out the NAME could be root but how can the name be bin or ssshd...vat is the difference between NAME and user ID. besdies vat does :: indicate ...does it indicate skipping a particluar field.

thanks

Rajesh

Accounts such as bin, sys, mail, httpd, and so forth are used by the system - some processes run as these "users", files are owned by them, etc. If you fiddle with these, things will break. Nobody actually logs into the system as these users hence they have no shell listed (or some will have /bin/false).

You are correct in your assumption that :: means the field between the two colon delimeters is empty.

Cheers
ZB