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Technical Reference: Base Operating System and Extensions, Volume 1

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


Accesses the basic user information in the user database.


Standard C Library (libc.a)


#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 ( )


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.


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.


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.

Implementation Specifics

These subroutines are part of Base Operating System (BOS) Runtime.


/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 5.1 General Programming Concepts: Writing and Debugging Programs.

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