Hi, On 23 April 2010 08:52, Chris Adams <cmadams@xxxxxxxxxx> wrote: > Once upon a time, Suvayu Ali <fatkasuvayu+linux@xxxxxxxxx> said: >> I have never properly understood the leading bit in permissions. (the 0 >> in the 0755) Could you point me to some easily understandable resource? > > The leading 3 bits is essentially an add-on to each of the user, group, > and other sections. For user and group, the corresponding bit is the > set-id bit. For executable filess with the set-user-id bit (e.g. 4xxx) > or set-group-id bit (e.g. 2xxx) set, the executable runs as the files > owner or group, not the calling user or group. > > For directories, set-group-id means that new entries in that directory > inherit the group from the directory instead of the calling group. > > The bit corresponding to other (e.g. 1xxx) is called the "sticky" bit. > On directories (such as /tmp), it means that only users/groups with > permissions to a file can delete it. > After reading your response I knew more precisely what to look for and after some searching and looking @ `info coreutils "File permissions" "Mode Structure", I think I understand them now. However I failed to find how to see whether any of those bits are set for a file. I tried `ls -l ' in /bin, /usr/bin, and /tmp but didn't notice anything obvious. I also failed to find any appropriate option for ls to list it either. Am I looking in the wrong place? Also in what situations would seting the setuid or setgid bits help? I could think of some, like writing configuration files for the application which are otherwise owned by someone else, maybe for a web server or a daemon or maybe some automated backup solution. Are these valid scenarios? > In old Unix, the sticky bit on an executable changed the way the kernel > paged it into and out of RAM, but I don't believe Linux uses it. > -- > Chris Adams <cmadams@xxxxxxxxxx> -- Suvayu Open source is the future. It sets us free. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
