GETUTXENT(3C) Standard C Library Functions GETUTXENT(3C)


getutxent, getutxid, getutxline, pututxline, setutxent, endutxent,
utmpxname, getutmp, getutmpx, updwtmp, updwtmpx - user accounting
database functions


#include <utmpx.h>

struct utmpx *getutxent(void);

struct utmpx *getutxid(const struct utmpx *id);

struct utmpx *getutxline(const struct utmpx *line);

struct utmpx *pututxline(const struct utmpx *utmpx);

void setutxent(void);

void endutxent(void);

int utmpxname(const char *file);

void getutmp(struct utmpx *utmpx, struct utmp *utmp);

void getutmpx(struct utmp *utmp, struct utmpx *utmpx);

void updwtmp(char *wfile, struct utmp *utmp);

void updwtmpx(char *wfilex, struct utmpx *utmpx);


These functions provide access to the user accounting database, utmpx
(see utmpx(5)). Entries in the database are described by the definitions
and data structures in <utmpx.h>.

The utmpx structure contains the following members:

char ut_user[32]; /* user login name */
char ut_id[4]; /* /etc/inittab id */
/* (usually line #) */
char ut_line[32]; /* device name */
/* (console, lnxx) */
pid_t ut_pid; /* process id */
short ut_type; /* type of entry */
struct exit_status ut_exit; /* exit status of a process */
/* marked as DEAD_PROCESS */
struct timeval ut_tv; /* time entry was made */
int ut_session; /* session ID, used for */
/* windowing */
short ut_syslen; /* significant length of */
/* ut_host */
/* including terminating null */
char ut_host[257]; /* host name, if remote */

The exit_status structure includes the following members:

short e_termination; /* termination status */
short e_exit; /* exit status */

The getutxent() function reads in the next entry from a utmpx database.
If the database is not already open, it opens it. If it reaches the end
of the database, it fails.

The getutxid() function searches forward from the current point in the
utmpx database until it finds an entry with a ut_type matching
id->ut_type, if the type specified is RUN_LVL, BOOT_TIME, DOWN_TIME,
OLD_TIME, or NEW_TIME. If the type specified in id is INIT_PROCESS,
LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS, then getutxid() will return
a pointer to the first entry whose type is one of these four and whose
ut_id member matches id->ut_id. If the end of database is reached without
a match, it fails.

The getutxline() function searches forward from the current point in the
utmpx database until it finds an entry of the type LOGIN_PROCESS or
USER_PROCESS which also has a ut_line string matching the line->ut_line
string. If the end of the database is reached without a match, it fails.

The pututxline() function writes the supplied utmpx structure into the
utmpx database. It uses getutxid() to search forward for the proper
place if it finds that it is not already at the proper place. It is
expected that normally the user of pututxline() will have searched for
the proper entry using one of the getutx() routines. If so, pututxline()
will not search. If pututxline() does not find a matching slot for the
new entry, it will add a new entry to the end of the database. It
returns a pointer to the utmpx structure. When called by a non-root
user, pututxline() invokes a setuid() root program to verify and write
the entry, since the utmpx database is normally writable only by root.
In this event, the ut_name member must correspond to the actual user name
associated with the process; the ut_type member must be either
USER_PROCESS or DEAD_PROCESS; and the ut_line member must be a device
special file and be writable by the user.

The setutxent() function resets the input stream to the beginning. This
should be done before each search for a new entry if it is desired that
the entire database be examined.

The endutxent() function closes the currently open database.

The utmpxname() function allows the user to change the name of the
database file examined from /var/adm/utmpx to any other file, most often
/var/adm/wtmpx. If the file does not exist, this will not be apparent
until the first attempt to reference the file is made. The utmpxname()
function does not open the file, but closes the old file if it is
currently open and saves the new file name. The new file name must end
with the "x" character to allow the name of the corresponding utmp file
to be easily obtainable.; otherwise, an error value of 0 is returned. The
function returns 1 on success.

The getutmp() function copies the information stored in the members of
the utmpx structure to the corresponding members of the utmp structure.
If the information in any member of utmpx does not fit in the
corresponding utmp member, the data is silently truncated. (See
getutent(3C) for utmp structure)

The getutmpx() function copies the information stored in the members of
the utmp structure to the corresponding members of the utmpx structure.
(See getutent(3C) for utmp structure)

The updwtmp() function can be used in two ways.

If wfile is /var/adm/wtmp, the utmp format record supplied by the caller
is converted to a utmpx format record and the /var/adm/wtmpx file is
updated (because the /var/adm/wtmp file no longer exists, operations on
wtmp are converted to operations on wtmpx by the library functions.

If wfile is a file other than /var/adm/wtmp, it is assumed to be an old
file in utmp format and is updated directly with the utmp format record
supplied by the caller.

The updwtmpx() function writes the contents of the utmpx structure
pointed to by utmpx to the database.

utmpx structure
The values of the e_termination and e_exit members of the ut_exit
structure are valid only for records of type DEAD_PROCESS. For utmpx
entries created by init(8), these values are set according to the result
of the wait() call that init performs on the process when the process
exits. See the wait(3C), manual page for the values init uses.
Applications creating utmpx entries can set ut_exit values using the
following code example:

u->ut_exit.e_termination = WTERMSIG(process->p_exit)
u->ut_exit.e_exit = WEXITSTATUS(process->p_exit)

See wait.h(3HEAD) for descriptions of the WTERMSIG and WEXITSTATUS

The ut_session member is not acted upon by the operating system. It is
used by applications interested in creating utmpx entries.

For records of type USER_PROCESS, the nonuserx() macro uses value of the
ut_exit.e_exit member to mark utmpx entries as real logins (as opposed to
multiple xterms started by the same user on a window system). This allows
the system utilities that display users to obtain an accurate indication
of the number of actual users, while still permitting each pty to have a
utmpx record (as most applications expect). The NONROOT_USRX macro
defines the value that login places in the ut_exit.e_exit member.


Upon successful completion, getutxent(), getutxid(), and getutxline()
each return a pointer to a utmpx structure containing a copy of the
requested entry in the user accounting database. Otherwise a null
pointer is returned.

The return value may point to a static area which is overwritten by a
subsequent call to getutxid () or getutxline().

Upon successful completion, pututxline() returns a pointer to a utmpx
structure containing a copy of the entry added to the user accounting
database. Otherwise a null pointer is returned.

The endutxent() and setutxent() functions return no value.

A null pointer is returned upon failure to read, whether for permissions
or having reached the end of file, or upon failure to write.


These functions use buffered standard I/O for input, but pututxline()
uses an unbuffered write to avoid race conditions between processes
trying to modify the utmpx and wtmpx files.

Applications should not access the utmpx and wtmpx databases directly,
but should use these functions to ensure that these databases are
maintained consistently.


user access and accounting information

history of user access and accounting information


See attributes(7) for descriptions of the following attributes:

|Interface Stability | See below. |
|MT-Level | Unsafe |

The endutxent(), getutxent(), getutxid(), getutxline(), pututxline(), and
setutxent() functions are Standard.


getutent(3C), ttyslot(3C), wait(3C), wait.h(3HEAD), utmpx(5),
attributes(7), standards(7)


The most current entry is saved in a static structure. Multiple accesses
require that it be copied before further accesses are made. On each call
to either getutxid() or getutxline(), the routine examines the static
structure before performing more I/O. If the contents of the static
structure match what it is searching for, it looks no further. For this
reason, to use getutxline() to search for multiple occurrences it would
be necessary to zero out the static after each success, or getutxline()
would just return the same structure over and over again. There is one
exception to the rule about emptying the structure before further reads
are done. The implicit read done by pututxline() (if it finds that it is
not already at the correct place in the file) will not hurt the contents
of the static structure returned by the getutxent(), getutxid(), or
getutxline() routines, if the user has just modified those contents and
passed the pointer back to pututxline().

November 21, 2014 GETUTXENT(3C)