The power of find command in Linux – advanced.

2010-05-24 2 min read Linux

Generally whoever uses Linux, would know about the find command. Find the man page <a href="http://amit.themafia.info/phpMan.php?parameter=find&mode=man" target="_blank">here.

There are also lots of blogs, tutorials and other articles on find command on the web, so why write another one. Because it&#8217;s worth every word spent on it πŸ™‚
find is a very powerful command, let&#8217;s see how (options for find command from man page and usage):

–depth β€” Process each directory&#8217;s contents before the directory itself.
–maxdepth β€” Descend at most <span style="text-decoration: underline;">levels (a non-negative integer) levels of directories below the command line arguments.
–xdev β€” Don&#8217;t descend directories on other filesystems.
–executable β€” Matches files which are executable and directories which are searchable (in a file name resolution sense).
This takes into account access control lists and other permissions artefacts which the -perm test ignores.
–iname β€” Like -name, but the match is case insensitive.
–nogroup β€” No group corresponds to file&#8217;s numeric group ID.
–nouser β€” No user corresponds to file&#8217;s numeric user ID.
–fls <span style="text-decoration: underline;">file β€” True; like -ls but write to <span style="text-decoration: underline;">file like -fprint.
–ok <span style="text-decoration: underline;">command β€” Like -exec but ask the user first (on the standard input);
–print0 β€” True; print the full file name on the standard output, followed by a null character
(instead of the newline character that -print uses).
–printf <span style="text-decoration: underline;">format β€” True; print <span style="text-decoration: underline;">format on the standard output, interpreting &#8217;&#8217; escapes and &#8217;%&#8217; directives.

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Inotify Example - Introduction to Inotify with a C Program Example

2010-05-24 1 min read C Programs Learning Linux

<a href="http://www.thegeekstuff.com/2010/04/inotify-c-program-example/">Inotify Example: Introduction to Inotify with a C Program Example:

<a class="zem_slink freebase/en/inotify" href="http://en.wikipedia.org/wiki/Inotify" title="Inotify" rel="wikipedia">inotify utility is an effective tool to monitor and notify <a class="zem_slink freebase/en/file_system" href="http://en.wikipedia.org/wiki/File_system" title="File system" rel="wikipedia">filesystem changes. You can specify a list of files and directories that needs to be monitored by inotify. This <a class="zem_slink freebase/guid/9202a8c04000641f8000000000023d0f" href="http://en.wikipedia.org/wiki/Library" title="Library" rel="wikipedia">library is used by various other programs. For example, <a class="zem_slink freebase/en/cpan" href="http://www.cpan.org/" title="CPAN" rel="homepage">CPAN module Linux::Inotify is developed based on this library.
iNotify Execution Flow

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Working with FTP Directories.

2010-05-19 1 min read Linux

If you have to manage some ftp site, I can understand you pain in managing the site with FTP. Specially if you are managing a site where you need to edit the files. Without shelling out some decent amount of money you will not get decent editor which can help you edit the files directly over ftp. So today I spent my time looking for a good solution and UREKA I found it.

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Disk identification by UUID in Fedora.

2010-05-19 2 min read GNOME Linux

Yesterday I managed to delete my complete /usr directory and thus had to re-install my OS but I learned something new yesterday which I didn&#8217;t know earlier or actually never bothered to find out.br /br /All the partitions are mounted by udev using the UUID or label now. Finding the label of setting the label is easy but that was not the case with UUID (at least till you dont know how to do it). So finally I set my foot to search it. Heres some of the things that I found:br /br /bblkid/b – Gives you a list like below for all your partitions:br //dev/sda6: UUID=&#8221;8D8A-6CF1&#8221; TYPE=&#8221;vfat&#8221; LABEL=&#8221;Backup&#8221; br /So this is sufficient to modify your fstab to refer to the UUID or label instead of the drive. So whats the change in fstab. If the earlier entry looks likebr //dev/sdb6nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp; /media/Bkup3nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp; vfatnbsp;nbsp;nbsp; uid=500,nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp; 0 0br /then you can change this to :br /UUID=&#8221;8D8A-6CF1&#8221;nbsp;nbsp; /media/Bkup3nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp; vfatnbsp;nbsp;nbsp; uid=500,nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp; 0 0br /What is the benifit:br /β€”β€”β€”β€”β€”β€”β€”br /When you re-format your Hard Disk there is a likely possibility that the dev name could well change and thus completely changing the mount points for all your fstab entries. This is really a pain if you have 10 or more partitions like the way I have. So if you use label or UUID then they never change and your mount points remain the same.br /br /Effective use: Use autofs package to automatically mount all your partitions. Autofs mounts the package at /media/LABEL, so before you hit to start your autofs label all your disks.br /br /Other ways to find the disk labels and UUID&#8217;s:br /ls /dev/disk/by-uuid –gt; simplest way. :)br /br /Will get back to this later with more details.br /br /

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How to write a Linux virus – well or a trojan.

2010-05-18 2 min read Fedora Linux

<a href="http://www.geekzone.co.nz/foobar/6229" target="_blank">How to write a Linux virus

and the folloup thereof

<a href="http://www.geekzone.co.nz/foobar/6236" target="_blank">Follow up: How to write a Linux virus

Thats quite a lot of discussion and an interesting one too. I too liked the point that the authour is trying to make, that is Linux too is not completely safe. I would rather like to put it as not &#8221;Fool Proof&#8221;.

But no one is fool. Its just the matter of time when you do something foolish. People do keep thinking about various things and keep working. That being the case, it is not too difficult that someone would actually run the program. But the caveat is that the program/virus/trojan would still show up at some places. So you need to do few more things for this to work. If you are keen on doing this, then you need to atleast add these:

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