求助 rhel 4 下 w 和who命令显示错误

用w和who查看登陆的用户时，显示的有很多用户，都是很多天前登陆的用户，他们已经退出了。从进程里也查看不到。但是不知道为什么仍然显示出来：


[gwf@blade1 ~]$ who

jl pts/2 Oct 9 17:00
lgq pts/3 Sep 27 22:18
shxj pts/4 Sep 20 13:45 (210.73.19.235)
lgq pts/5 Sep 25 19:25
hym pts/6 Sep 21 11:38
lgq pts/7 Oct 3 12:38
sz pts/9 Sep 22 09:13
gwf pts/10 Oct 9 21:40
hym pts/9 Sep 18 08:34 (210.73.18.109)
lgq pts/12 Sep 21 11:28
lgq pts/13 Sep 27 22:15
sz pts/11 Sep 22 09:13
sz pts/14 Sep 22 09:13
yangchen pts/18 Sep 28 09:56
szhu pts/15 Sep 22 09:18
guowenfe pts/20 Oct 9 21:51
sz pts/1 Sep 21 08:16
gwf pts/40 Sep 25 09:40
lgq pts/23 Sep 22 10:34
huyemin :1003 Sep 21 11:38 (210.73.18.109)
ligq :1006 Sep 21 11:27 (210.73.19.97)
yl :1007 Sep 25 08:48 (210.73.19.41)
yl :1009 Sep 27 19:25 (60.166.211.159)
yl :1010 Sep 25 09:33 (210.73.19.223)
yl :1011 Sep 25 09:35 (210.73.19.223)
yl :1012 Sep 27 19:30 (60.166.223.51)
y :1013 Sep 27 19:43 (124.73.89.28)



[gwf@blade1 ~]$ w
22:01:13 up 86 days, 10:23, 28 users, load average: 0.31, 0.38, 0.37
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
jl pts/2 - 17:00 1.00s 3.28s 0.38s -bash
lgq pts/3 - 27Sep09 3days 3:11m 0.50s /bin/bash
lgq pts/5 - 25Sep09 7days 3.85s 3.43s python /home/ligq/IMFIT/trunk/imfit.py -g
hym pts/6 - 21Sep09 18days 0.00s 4.90s kdeinit: kded
lgq pts/7 - 03Oct09 6days 0.09s 0.09s /bin/bash
sz pts/9 - 22Sep09 17days 0.00s 5.06s kdeinit: kded
gwf pts/10 - 21:40 5:14 0.12s 0.12s -bash
lgq pts/12 - 21Sep09 18days 0.00s 4.97s kdeinit: kded
lgq pts/13 - 27Sep09 11days 0.21s 0.21s /bin/bash
sz pts/11 - 22Sep09 17days 15.31s 0.22s -csh
sz pts/14 - 22Sep09 17days 16.05s 0.11s -csh
yangchen pts/18 - 28Sep09 11days 0.00s 3.73s kdeinit: kded
sz pts/15 - 22Sep09 17days 0.18s 0.14s -csh
gwf pts/20 - 21:51 0.00s 0.04s 0.01s w
lgq pts/23 - 22Sep09 6days 31.37s 0.96s /bin/bash
hym :1003 210.73.18.109 21Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver
lgq :1006 210.73.19.97 21Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver
yl :1007 210.73.19.41 25Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver
yl :1009 60.166.211.159 27Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver
yl :1010 210.73.19.223 25Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver
yl :1011 210.73.19.223 25Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver
yl :1012 60.166.223.51 27Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver
yl :1013 124.73.89.28 27Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver
yangchen :1014 210.73.18.229 28Sep09 ?xdm? 4days 0.00s /bin/bash /usr/NX/bin/nxserver