endutxent man page

Prolog

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endutxent, getutxent, getutxid, getutxline, pututxline, setutxent — user accounting database functions

Synopsis

#include <utmpx.h>

void endutxent(void);
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);

Description

These functions shall provide access to the user accounting database.

The getutxent() function shall read the next entry from the user accounting database. If the database is not already open, it shall open it. If it reaches the end of the database, it shall fail.

The getutxid() function shall search forward from the current point in the database. If the ut_type value of the utmpx structure pointed to by id is BOOT_TIME, OLD_TIME, or NEW_TIME, then it shall stop when it finds an entry with a matching ut_type value. If the ut_type value is INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS, then it shall stop when it finds an entry whose type is one of these four and whose ut_id member matches the ut_id member of the utmpx structure pointed to by id. If the end of the database is reached without a match, getutxid() shall fail.

The getutxline() function shall search forward from the current point in the database until it finds an entry of the type LOGIN_PROCESS or USER_PROCESS which also has a ut_line value matching that in the utmpx structure pointed to by line. If the end of the database is reached without a match, getutxline() shall fail.

The getutxid() or getutxline() function may cache data. For this reason, to use getutxline() to search for multiple occurrences, the application shall zero out the static data after each success, or getutxline() may return a pointer to the same utmpx structure.

There is one exception to the rule about clearing 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 user accounting database) shall not modify the static structure returned by getutxent(), getutxid(), or getutxline(), if the application has modified this structure and passed the pointer back to pututxline().

For all entries that match a request, the ut_type member indicates the type of the entry. Other members of the entry shall contain meaningful data based on the value of the ut_type member as follows:

ut_type MemberOther Members with Meaningful Data
EMPTYNo others
BOOT_TIMEut_tv
OLD_TIMEut_tv
NEW_TIMEut_tv
USER_PROCESSut_id, ut_user (login name of the user), ut_line, ut_pid, ut_tv
INIT_PROCESSut_id, ut_pid, ut_tv
LOGIN_PROCESSut_id, ut_user (implementation-defined name of the login process), ut_line, ut_pid, ut_tv
DEAD_PROCESSut_id, ut_pid, ut_tv

An implementation that provides extended security controls may impose implementation-defined restrictions on accessing the user accounting database. In particular, the system may deny the existence of some or all of the user accounting database entries associated with users other than the caller.

If the process has appropriate privileges, the pututxline() function shall write out the structure into the user accounting database. It shall search for a record as if by getutxid() that satisfies the request. If this search succeeds, then the entry shall be replaced. Otherwise, a new entry shall be made at the end of the user accounting database.

The endutxent() function shall close the user accounting database.

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

These functions need not be thread-safe.

Return Value

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

The endutxent() and setutxent() functions shall not return a value.

Errors

No errors are defined for the endutxent(), getutxent(), getutxid(), getutxline(), and setutxent() functions.

The pututxline() function may fail if:

EPERM
The process does not have appropriate privileges.

The following sections are informative.

Application Usage

The sizes of the arrays in the structure can be found using the sizeof operator.

See Also

The Base Definitions volume of POSIX.1‐2008, <utmpx.h>

Info

2013 IEEE/The Open Group POSIX Programmer's Manual