Technical Reference: Base Operating System and Extensions, Volume 1

getpwent, getpwuid, getpwnam, putpwent, setpwent, or endpwent Subroutine

Purpose

Accesses the basic user information in the user database.

Library

Standard C Library (libc.a)

Syntax

#include <sys/types.h>
#include <pwd.h>

struct passwd *getpwent ( )

struct passwd *getpwuid ( UserID) uid_t UserID;

struct passwd *getpwnam ( Name) char *Name;

int putpwent ( Password, File) struct passwd *Password; FILE *File;

void setpwent ( )

void endpwent ( )

Description

Attention: All information generated by the getpwent, getpwnam, and getpwuid subroutines is stored in a static area. Subsequent calls to these subroutines overwrite this static area. To save the information in the static area, applications should copy it.

These subroutines access the basic user attributes.

The setpwent subroutine opens the user database if it is not already open. Then, this subroutine sets the cursor to point to the first user entry in the database. The endpwent subroutine closes the user database.

The getpwent, getpwnam, and getpwuid subroutines return information about a user. These subroutines do the following:

getpwent	Returns the next user entry in the sequential search.
getpwnam	Returns the first user entry in the database whose name matches the Name parameter.
getpwuid	Returns the first user entry in the database whose ID matches the UserID parameter.

The putpwent subroutine writes a password entry into a file in the colon-separated format of the /etc/passwd file.

The user Structure

The getpwent, getpwnam, and getpwuid subroutines return a user structure. This structure The user structure is defined in the pwd.h file and has the following fields:

`pw_name`	Contains the name of the user name.
`pw_passwd`	Contains the user's encrypted password. Note If the password is not stored in the /etc/passwd file and the invoker does not have access to the shadow file that contains passwords, this field contains an undecryptable string, usually an `*` (asterisk).
`pw_uid`	Contains the user's ID.
`pw_gid`	Identifies the user's principal group ID.
`pw_gecos`	Contains general user information.
`pw_dir`	Identifies the user's home directory.
`pw_shell`	Identifies the user's login shell.

Note

If Network Information Services (NIS) is enabled on the system, these subroutines attempt to retrieve the information from the NIS authentication server before attempting to retrieve the information locally.

Parameters

File	Points to an open file whose format is similar to the /etc/passwd file format.
Name	Specifies the user name.
Password	Points to a password structure. This structure contains user attributes.
UserID	Specifies the user ID.

Security

Files Accessed:

Mode	File
rw	/etc/passwd (write access for the putpwent subroutine only)
r	/etc/security/passwd (if the password is desired)

Return Values

The getpwent, getpwnam, and getpwuid subroutines return a pointer to a valid password structure if successful. Otherwise, a null pointer is returned.

The getpwent subroutine will return a null pointer and an errno value of ENOATTR when it detects a corrupt entry. To get subsequent entries following the corrupt entry, call the getpwent subroutine again.

Files

/etc/passwd

Contains user IDs and their passwords

Related Information

The getgrent (getgrent, getgrgid, getgrnam, setgrent, or endgrent Subroutine) subroutine, getgroupattr (getgroupattr, IDtogroup, nextgroup, or putgroupattr Subroutine) subroutine, getuserattr (getuserattr, IDtouser, nextuser, or putuserattr Subroutine) subroutine, getuserpw, putuserpw, or putuserpwhist (getuserpw, putuserpw, or putuserpwhist Subroutine) subroutine, setuserdb subroutine.

List of Security and Auditing Subroutines, Subroutines, Example Programs, and Libraries in AIX 5L Version 5.2 General Programming Concepts: Writing and Debugging Programs.