Check existence of a login


 
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# 8  
Old 03-04-2008
Quote:
Originally Posted by fpmurphy
Wrong. The getpwnam() searches the user database for an entry with a matching name.
Note, that I did not say searches /etc/passwd.
Originally, Linux manpage said it:

GETPWNAM

On a Mandrake 2006.0, the beginning of the manpage I have is exactly the same. A bit confusing...
# 9  
Old 03-04-2008
Quote:
Originally Posted by fpmurphy
Wrong. The getpwnam() searches the user database for an entry with a matching name.
Note, that I did not say searches /etc/passwd.
Originally, it seems it did search /etc/passwd, at least on Linux:
GETPWNAM

On the Mandrake 2006.0 I am (unfortunately) compelled to use at work, the beginning of the manpage I have is exactly the same...

To take just what happens on Solaris for getpwnam(3) and login(1)
man pages section 3: Basic Library Functions: getpwnam_r(3C)
man pages section 1: User Commands: login(1)

I understand it is possible for a user to log in since login(1) relies on PAM, without that his entry is necessarily recorded in the password database. So the tilde expandion in a public shell like bash would fail in this case (as for ksh, there is no call to any pam_ function in bash-3.2, only calls to getpw* , I double-checked), but would succeed if nsswitch.conf and pam.conf lead to the same files.

Is this correct? If yes, then why isn't PAM used everywhere? Can't understand this.
# 10  
Old 03-04-2008
This was the point of my earlier post, but sublimated.
PAM provides a stackable method for transparent scrutiny of credentials presented to the system for account, authentication and accounting.
Using PAM's own API on systems equipped with it the existence of a user account can be inferred adequately, Without, one must be able to query whatever source of information is needed to verify multiple definitions of an account and it's viability.

Some systems do without PAM by philosophy and some systems predate PAM and continue with previous methods for compatibility. Personally I find the API for PAM to be cumbersome, but far from impossible.

I've worked in a shop that continued using HP 10.x in line with progressive linux installations. In this case all that could be done was design around PAM for compatibility.
# 11  
Old 03-06-2008
Quote:
Originally Posted by ramen_noodle
This was the point of my earlier post, but sublimated.
Apologies Smilie

I had a look at pam(8) manpage in the meantime... It sounds complicated, at least in portability point of view. More precisely, I don't mean than PAM is not portable. But it may be not installed on a given system, or may be installed but neither configured or even not used at all. How to know? No way, except develop my application with both PAM and getpw*, and choose the right option system by system... Smilie
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