> bugs:*:101:100:Bug Filer:/home/hiwis/bugs:/bin/go
> x11:*:102:100:Mr. X:/home/hiwis/x11:/bin/go
> lp:*:110:32766:Max Hit Lp:/var/spool/laser1:/bin/go
> tftp:*:113:32766:Trivial Ftp:/:/dev/null
> ftp:*:200:32766:Anonymous Ftp,,,:/mit/ftp:/dev/null
> anon:*:200:32766:Anonymous Sup,,,:/mit/ftp/pub/NetBSD:/dev/null
> httpd:*:202:40:Humpty Dumpty:/usr/local/etc/httpd:/dev/null
> 
> <root@wipux2:~> grep -v [a-z] /etc/passwd
> tftp:*:113:32766:Trivial Ftp:/:/dev/null
> <root@wipux2:~>
> 
> Why is grep outputting the 'tftp' line ?

Your shell is expanding the "[a-z]" part of the command above, and so
the output from grep will depend on what is in your cwd. Try escaping
the regexp: i.e.

grep -v '[a-z]' /etc/passwd

Alistair