pjh@mccc.UUCP (Peter J. Holsberg) (02/12/88)
A while ago, I expressed interest in a method of creating a file of
user logins/outs. Many people made many helpful suggestions, but
I find myself without a solution.
One suggestion, which came very close, was to trap 0 1 3 with a line in
/etc/profile so that on ^d logout (or hangup, etc.) a line with "who am
i" information would be written to /usr/.logins. I found that this
worked quite well except for one thing: despite the fact that the login
time is accurate, the logout time is always about one second after the
login time, regardless of the actual logout!
So, how can I make "who am i", imbedded in a 'trap' statement execute at
the instant of the trap, rather than when /etc/profile is first
executed? Many thanks for your help.
--
Peter Holsberg UUCP: {rutgers!}princeton!mccc!pjh
Technology Division CompuServe: 70240,334
Mercer College GEnie: PJHOLSBERG
Trenton, NJ 08690 Voice: 1-609-586-4800gwyn@brl-smoke.ARPA (Doug Gwyn ) (02/13/88)
In article <209@mccc.UUCP>, pjh@mccc.UUCP (Peter J. Holsberg) writes: > One suggestion, which came very close, was to trap 0 1 3 with a line in > /etc/profile so that on ^d logout (or hangup, etc.) a line with "who am > i" information would be written to /usr/.logins. I found that this > worked quite well except for one thing: despite the fact that the login > time is accurate, the logout time is always about one second after the > login time, regardless of the actual logout! I suspect the only problem is that you forgot that the arguments to the "trap" built-in would be evaluated twice, once at the time of executing the "trap" built-in, and once (with whatever the result of the first evaluation was) when the trap fires at logout time. Once you realize this, the solution is obvious: quote the "who am i" so that it will not be evaluated when "trap" is set.
pjh@mccc.UUCP (Peter J. Holsberg) (02/14/88)
In article <7255@brl-smoke.ARPA> gwyn@brl-smoke.ARPA (Doug Gwyn ) writes: |In article <209@mccc.UUCP>, pjh@mccc.UUCP (Peter J. Holsberg) writes: |> One suggestion, which came very close, was to trap 0 1 3 with a line in |> /etc/profile so that on ^d logout (or hangup, etc.) a line with "who am |> i" information would be written to /usr/.logins. I found that this |> worked quite well except for one thing: despite the fact that the login |> time is accurate, the logout time is always about one second after the |> login time, regardless of the actual logout! | |I suspect the only problem is that you forgot that the arguments to the |"trap" built-in would be evaluated twice, once at the time of executing |the "trap" built-in, and once (with whatever the result of the first |evaluation was) when the trap fires at logout time. Once you realize |this, the solution is obvious: quote the "who am i" so that it will not |be evaluated when "trap" is set. Here's what's in my /etc/profile now: echo IN: "\t" $LOGNAME "\t" `tty` "\t" `date` >> /usr/pjh/.logins trap 'echo OUT: "\t" $LOGNAME " \t\c" >>/usr/.logins; `tty` >>/usr/.logins `date` >> /usr/.logins' 0 1 3 The 'trap' doesnm't work. Please suggest modifications. (I've tried many but clearly, I've overlooked the one that will work.) Thx. -- Peter Holsberg UUCP: {rutgers!}princeton!mccc!pjh Technology Division CompuServe: 70240,334 Mercer College GEnie: PJHOLSBERG Trenton, NJ 08690 Voice: 1-609-586-4800
wnp@dcs.UUCP (Wolf N. Paul) (02/16/88)
In article <213@mccc.UUCP> pjh@mccc.UUCP (Peter J. Holsberg) writes: >Here's what's in my /etc/profile now: > >echo IN: "\t" $LOGNAME "\t" `tty` "\t" `date` >> /usr/pjh/.logins > >trap 'echo OUT: "\t" $LOGNAME " \t\c" >>/usr/.logins; `tty` >>/usr/.logins `date` >> /usr/.logins' 0 1 3 > > >The 'trap' doesnm't work. Please suggest modifications. (I've tried I tried something yesterday related to a discussion of the MKS shell (MS DOS), where someone wanted a ".logout" equivalent for the Korn shell. In /etc/profile I put the following line: trap ". $HOME/.logout" 0 1 3 and in $HOME/.logout any commands that I want executed every time I log out. This works on my Microport System V machine. Actually, the trap line in /etc/profile is within a case statement which checks for a $0 of "-sh" - since we don't want this to execute whenever we leave ANY old shell, but only when we leave the login shell. Putting whatever you want to happen on logout into a separate shell script removes all of the ambiguities and pitfalls of when it will be interpreted by the shell - it won't, until the trap is sprung and the separate shell script is read. ------- -- ------------------- Wolf N. Paul Phone: (214) 306-9101 (h) (214) 404-8077 (w) 3387 Sam Rayburn Run UUCP: ihnp4!killer!{dcs, doulos}!wnp Carrollton, TX 75007 INTERNET: wnp@dcs.UUCP ESL: 62832882
gwyn@brl-smoke.ARPA (Doug Gwyn ) (02/17/88)
Ok, here's a working version. I chose to evaluate $LOGNAME when the trap is set, to forestall any later forgery, but you can change this if you wish, once you figure out the general principle by studying this example: echo "IN:\t$LOGNAME\t`tty`\t`date`" >> /usr/.logins trap "echo \"OUT:\t$LOGNAME\t\`tty\`\t\`date\`\" >> /usr/.logins" 0 1 15
davidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr) (02/17/88)
I tried "who am i" on Ultrix and Xenix, and looked in a real SysV
manual. All seem to list the login time of the user, rether than the
current time. May I comment to your attention the "date" command.
How about:
trap "echo `who am i` `date`" 0 1 3
this gives you the one line output you might want.
--
bill davidsen (wedu@ge-crd.arpa)
{uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -melevy@ttrdc.UUCP (Daniel R. Levy) (02/17/88)
In article <7255@brl-smoke.ARPA>, gwyn@brl-smoke.ARPA (Doug Gwyn ) writes: # In article <209@mccc.UUCP>, pjh@mccc.UUCP (Peter J. Holsberg) writes: # > One suggestion, which came very close, was to trap 0 1 3 with a line in # > /etc/profile so that on ^d logout (or hangup, etc.) a line with "who am # > i" information would be written to /usr/.logins. I found that this # > worked quite well except for one thing: despite the fact that the login # > time is accurate, the logout time is always about one second after the # > login time, regardless of the actual logout! # I suspect the only problem is that you forgot that the arguments to the # "trap" built-in would be evaluated twice, once at the time of executing # the "trap" built-in, and once (with whatever the result of the first # evaluation was) when the trap fires at logout time. Once you realize # this, the solution is obvious: quote the "who am i" so that it will not # be evaluated when "trap" is set. A few notes: 1) "who am i" will print out the login time, not the present time. [I thought you knew better than this, Doug!] 2) There is no need to trap anything other than 0. Trapping 3 will definitely give misleading results if the user hits the QUIT character. trap '(/usr/bin/id; /bin/date) >> /usr/.logins' 0 3) Anything which is user-executable like this can be forged. A malicious user could clear out or alter /usr/.logins (which must be world writeable). The user can 'exec true' or 'kill -9 $$' or something like that to get out without leaving a record, or he can reset the trap manually. 4) There's no clear way out of the box without getting accounting software. -- |------------Dan Levy------------| Path: ..!{akgua,homxb,ihnp4,ltuxa,mvuxa, | an Engihacker @ | <most AT&T machines>}!ttrdc!ttrda!levy | AT&T Computer Systems Division | Disclaimer? Huh? What disclaimer??? |--------Skokie, Illinois--------|