getutx(3C)

NAME

getutx: endutxent(), getutxent(), getutxid(), getutxline(), pututxline(), setutxent() — access utmpx file entry

SYNOPSIS

#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);

Remarks:

The ut_addr field in the utmpx structure is deprecated and will be obsoleted and removed in a future release. If this field is needed, use the getuts() functions (see getuts(3C)).

DESCRIPTION

getutxent(), getutxid(), and getutxline() each return a pointer to a structure of the following type:

struct utmpx {
    char ut_user[24];         /* User login name */
    char ut_id[4];            /* /etc/inittab id (usually line #) */
    char ut_line[12];         /* device name (console, lnxx) */
    pid_t ut_pid;             /* process id */
    short ut_type;            /* type of entry */
    struct __exit_status {
        short __e_termination;  /* Process termination status */
        short __e_exit;         /* Process exit status */
        } ut_exit;            /* The exit status of a process */
                              /* marked as DEAD_PROCESS. */
    unsigned short ut_reserved1;  /* Reserved for future use */
    struct timeval {
        time_t  tv_sec;       /* seconds */
        long    tv_usec;      /* and microseconds */
        } ut_tv;              /* time entry was made */
    char ut_host[64];         /* host name, if remote; NOT SUPPORTED */
    unsigned long ut_addr;    /* Internet addr of host, if remote; */
                              /* TO BE OBSOLETED */
    char ut_reserved2[12] ;   /* Reserved for future use */
};

getutxent(): Reads in the next entry from a utmpx-like file. If the file is not already open, getutxent() opens it. If it reaches the end of the file, getutxent() fails.
getutxid(): Searches forward from the current point in the utmpx file until it finds an entry with a ut_type matching id->ut_type if the type specified is RUN_LVL, BOOT_TIME, OLD_TIME, or NEW_TIME. If the type specified in id is INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS, getutxid() returns a pointer to the first entry whose type is one of these four, and whose ut_id field matches id->ut_id. If end-of-file is reached without a match, getutxid() fails.
getutxline(): Searches forward from the current point in the utmpx file until it finds an entry of type LOGIN_PROCESS or USER_PROCESS that also has a ut_line string matching the line->ut_line string. If end-of-file is reached without a match, getutxline() fails.
pututxline(): Writes out the supplied utmpx structure into the utmpx file, translates the supplied utmpx structure into a utmp structure and writes it to a utmp file. pututxline() uses getutxid() to search forward for the proper location if it is not already there. It is normally expected that the application program has already searched for the proper entry by using one of the getutx() routines before calling pututxline(). If the search has already been made, pututxline() does not repeat it. If pututxline() does not find a matching slot for the new entry, it adds a new entry to the end of the file.
setutxent(): Resets the input stream to the beginning of the file. This should be done before each search for a new entry if it is desired that the entire file be examined.
endutxent(): Closes the currently open file.

The most current entry is saved in a static structure. Multiple accesses require that the structure be copied before further accesses are made. During each call to either getutxid() or getutxline(), the static structure is examined before performing more I/O. If the contents of the static structure match what the routine is searching for, no additional searching is done. Therefore, if using getutxline() to search for multiple occurrences, it is necessary to zero out the static structure after each success; otherwise getutxline() simply returns the same pointer over and over again. There is one exception to the rule about removing the structure before a new read: The implicit read done by pututxline() (if it finds that it is not already at the correct place in the file) does not alter the contents of the static structure returned by getutxent(), getutxid(), or getutxline() if the user has just modified those contents and passed the pointer back to pututxline().

RETURN VALUE

These functions return a NULL pointer upon failure to read (whether for permissions or having reached end-of-file), or upon failure to write. They also return a NULL pointer if the size of the file is not an integral multiple of sizeof(struct utmpx).

If pututxline() is successful, it returns a pointer to a static location containing the most current utmpx entry. The contents of this structure are identical to the contents of the supplied utmpx structure if successful. If pututline() fails upon writing to utmpx, it returns a NULL pointer. If putuline() is successful in writing to the utmpx file but fails in writing to the utmp file, then pututline() will behave as if it succeeded. Note that the utmpx file and the utmp file may not be in sync due to the above behavior. pututxline() is only guaranteed to have written to the utmpx file upon successful completion.

WARNINGS

The ut_addr field in the utmpx structure is deprecated and will be obsoleted and removed in a future release. If this field is needed, use the getuts() functions (see getuts(3C)).

FILES

/etc/utmp 
/etc/utmpx 
/var/adm/wtmp 

STANDARDS CONFORMANCE

endutxent(): XPG4.2

getutxent(): XPG4.2

getutxid(): XPG4.2

getutxline(): XPG4.2

pututxline(): XPG4.2

setutxent(): XPG4.2

getutx(3C)

Technical documentation

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