Shell Programming and Scripting

How would i compare the /etc/passwd file to a file on who is logged on at a snapshot of time. So if there is 15 people on and i have 300 names and passwords, i only want to see if those 15 people are legit, if not i want to see who isnt, i tried to use diff and comm but i think the file might be too big. Thanks.

diff and comm work on pretty darn big files. How are you building your current user list?

im using the output of who to a file
then the copying the /etc/passwd to a file
then trying to compare those 2 files
i was hoping to have them compare and give me the differences
they are big files you are right because i tried bdiff and i got the same think

im comparing like:

diff namecheck passcheck

namecheck = whos on
passcheck = my passwd file

im basically just getting these files back out when i want the difference between them

i was thinking i could maybe use join somewhere?

Thanks

I forgot to say that i first sorted in alphabetical order those two lists, Sorry!

what is the criteria for determining who is legitimate?

their criteria?

im not sure if i know what your asking but ill try to explain what im building..

when the etc/passwd is copied i got a list of users say...

rmamkfda
ajkfdasj;f
akfjalkjas
ajfa;jaaa
wuiewpur

when i output who to a file lets say i get....

rmamkfda
ajkfdasj;f
akfjalkjas
oiurwpqur
wuiewpur

So i know now that oiurwpqur does not belong, that is pretty much the gist but there is much more I have to do with the passwords, i just can't past the part where I compare names, no passwords are needed yet

Thanks a lot for you help and I hope this helps.



As im reading more on join, i think this will actually give me hte similarity between the two files, but could this be considered to big, let me read man largefile and answer my own question thanks

Question :

How the user "oiurwpqur" would be coming in 'who' o/p
when it is not part of /etc/passwd file ??


Is that name is coming from somewhere else ?