DESCRIPTION
These functions operate on the password database file which is described in passwd(5). Each entry in the database is defined by the structure
.Vt passwd found in the include file
.In pwd.h :
struct passwd {
char *pw_name; /* user name */
char *pw_passwd;/* encrypted password */
uid_t pw_uid; /* user uid */
gid_t pw_gid; /* user gid */
time_t pw_change; /* password change time */
char *pw_class; /* user access class */
char *pw_gecos; /* Honeywell login info */
char *pw_dir; /* home directory */
char *pw_shell; /* default shell */
time_t pw_expire; /* account expiration */
intpw_fields; /* internal: fields filled in */
};
The functions getpwnam and getpwuid search the password database for the given login name or user uid, respectively, always returning the first one encountered.
The getpwent function sequentially reads the password database and is intended for programs that wish to process the complete list of users.
The functions getpwent_r, getpwnam_r, and getpwuid_r are thread-safe versions of getpwent, getpwnam, and getpwuid, respectively. The caller must provide storage for the results of the search in the pwd, buffer, bufsize, and result arguments. When these functions are successful, the pwd argument will be filled-in, and a pointer to that argument will be stored in result. If an entry is not found or an error occurs, result will be set to NULL.
The setpassent function accomplishes two purposes. First, it causes getpwent to ‘‘rewind’’ to the beginning of the database. Additionally, if stayopen is non-zero, file descriptors are left open, significantly speeding up subsequent accesses for all of the routines. (This latter functionality is unnecessary for getpwent as it does not close its file descriptors by default.)
It is dangerous for long-running programs to keep the file descriptors open as the database will become out of date if it is updated while the program is running.
The setpwent function is identical to setpassent with an argument of zero.
The endpwent function closes any open files.