getutx(3G)

getutx: getutxent, getutxid, getutxline, pututxline, setutxent, endutxent, utmpxname, getutmp, getutmpx, updwtmp, updwtmpx -- access utmpx file entry

Synopsis

   cc [flag . . . ] file . . . -lgen [library] . . .
   
   #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);

Description

getutxent, getutxid, getutxline, and pututxline each return a pointer to a utmpx structure. (See utmpx(4).)

getutxent reads in the next entry from a utmpx-like file. If the file is not already open, it opens it. If it reaches the end of the file, it 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, then 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 the end of file is reached without a match, it fails.

getutxline searches forward from the current point in the utmpx file 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 file is reached without a match, it fails.

pututxline writes out the supplied utmpx structure into the utmpx file. 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 file. It returns a pointer to the utmpx structure.

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.

utmpxname allows the user to change the name of the file examined, from /var/adm/utmpx to any other file. It is most often expected that this other file will be /var/adm/wtmpx. If the file does not exist, this will not be apparent until the first attempt to reference the file is made. utmpxname does not open the file. It just 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 code of 0 is returned).

getutmp copies the information stored in the fields of the utmpx structure to the corresponding fields of the utmp structure. If the information in any field of utmpx does not fit in the corresponding utmp field, the data is truncated.

getutmpx copies the information stored in the fields of the utmp structure to the corresponding fields of the utmpx structure.

updwtmp checks the existence of wfile and its parallel file, whose name is obtained by appending an ``x'' to wfile. If only one of them exists, the second one is created and initialized to reflect the state of the existing file. utmp is written to wfile and the corresponding utmpx structure is written to the parallel file. If neither file exists nothing will happen.

updwtmpx checks the existence of wfilex and its parallel file, whose name is obtained by truncating the final ``x'' from wfilex. If only one of them exists, the second one is created and initialized to reflect the state of the existing file. utmpx is written to wfilex, and the corresponding utmp structure is written to the parallel file. If neither file exists nothing will happen.

Files

/var/adm/utmp, /var/adm/utmpx
/var/adm/wtmp, /var/adm/wtmpx

Errors

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

References

getut(3G), ttyslot(3C), utmp(4), utmpx(4)

Notices

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.

These routines 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.