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GETPWENT(3) Linux Programmer's Manual GETPWENT(3)


getpwent, setpwent, endpwent - get password file entry


#include <sys/types.h>
#include <pwd.h>
struct passwd *getpwent(void);
void setpwent(void);
void endpwent(void);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getpwent(), setpwent(), endpwent():


The getpwent() function returns a pointer to a structure containing the broken-out fields of a record from the password database (e.g., the local password file /etc/passwd, NIS, and LDAP). The first time getpwent() is called, it returns the first entry; thereafter, it returns successive entries.
The setpwent() function rewinds to the beginning of the password database.
The endpwent() function is used to close the password database after all processing has been performed.
The passwd structure is defined in <pwd.h> as follows:

struct passwd {
    char   *pw_name;       /* username */
    char   *pw_passwd;     /* user password */
    uid_t   pw_uid;        /* user ID */
    gid_t   pw_gid;        /* group ID */
    char   *pw_gecos;      /* user information */
    char   *pw_dir;        /* home directory */
    char   *pw_shell;      /* shell program */

When shadow(5) passwords are enabled (which is default on many GNU/Linux installations) the content of pw_passwd is usually not very useful. In such a case most passwords are stored in a separate file.
The variable pw_shell may be empty, in which case the system will execute the default shell (/bin/sh) for the user.
For more information about the fields of this structure, see passwd(5).


The getpwent() function returns a pointer to a passwd structure, or NULL if there are no more entries or an error occurred. If an error occurs, errno is set appropriately. If one wants to check errno after the call, it should be set to zero before the call.
The return value may point to a static area, and may be overwritten by subsequent calls to getpwent(), getpwnam(3), or getpwuid(3). (Do not pass the returned pointer to free(3).)


A signal was caught.
I/O error.
The maximum number (OPEN_MAX) of files was open already in the calling process.
The maximum number of files was open already in the system.
Insufficient memory to allocate passwd structure.
Insufficient buffer space supplied.


local password database file


Multithreading (see pthreads(7))

The getpwent() function is not thread-safe.
The setpwent() and endpwent() functions are thread-safe.


SVr4, 4.3BSD, POSIX.1-2001. The pw_gecos field is not specified in POSIX, but is present on most implementations.


fgetpwent(3), getpw(3), getpwent_r(3), getpwnam(3), getpwuid(3), putpwent(3), shadow(5), passwd(5)


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2013-06-21 GNU