we dare you totry it out anyway! (Please read the disclaimer first!) Super cow powersDifficulty: Easy Application: Debian A strange but endearing hidden feature within the highly regardedapt-get tool in Debian is its secret cow powers. Type the followingcommand to experience the wrath of the super cow powers: apt-get mooSome people really have too much time on their hands... Generating package relationship diagramsDifficulty: Easy Application: Debian The most critical part of the Debian system is the ability toinstall a package and have the dependencies satisfied automatically.If you would like a graphical representation of the relationshipsbetween these packages (this can be useful for seeing how the systemfits together), you can use the Graphviz package from Debian non-free(apt-get install graphviz) and the following command: apt-cache dotty > debian.dotThe command generated the graph file which can then be loaded intodotty: dotty debian.dotUnmount busy drivesDifficulty: Easy Application: bash You are probably all too familiar with the situation - you aretrying to unmount a drive, but keep getting told by your system thatit's busy. But what application is tying it up? A quick one-linerwill tell you: lsof +D /mnt/windowsThis will return the command and process ID of any tasks currentlyaccessing the /mnt/windows directory. You can then locate them, oruse the kill command to finish them off. Text fileconversionDifficulty: Easy Application: recode recode is a small utility that will save you loads of effort whenusing text files created on different platforms. The primary sourceof discontent is line breaks. In some systems, these are denoted witha line-feed character. In others, a carriage return is used. In stillmore systems, both are used. The end result is that if you areswapping text from one platform to another, you end up with too manyor too few line breaks, and lots of strange characters besides. However, the command parameters of recode are a little arcane, sowhy not combine this hack with HACK 26 in this feature, and set upsome useful aliases: alias dos2unix='recode dos/CR-LF..l1'alias unix2win='recode l1..windows-1250'alias unix2dos='recode l1..dos/CR-LF'There are plenty more options for recode - it can actually convertbetween a whole range of character sets. Check out the man pages formore information. Listingtoday's files onlyDifficulty: Easy Application: Various You are probably familiar with the problem. Sometime earlier inthe day, you created a text file, which now is urgently required.However, you can't remember what ridiculous name you gave it, andbeing a typical geek, your home folder is full of 836 differentfiles. How can you find it? Well, there are various ways, but thislittle tip shows you the power of pipes and joining together twopowerful shell commands: ls -al --time-style=+%D | grep `date +%D`The parameters to the ls command here cause the datestamp to beoutput in a particular format. The cunning bit is that the output isthen passed to grep. The grep parameter is itself a command (executedbecause of the backticks), which substitutes the current date intothe string to be matched. You could easily modify it to searchspecifically for other dates, times, filesizes or whatever. Combineit with HACK 26 to save typing! Avoid common mistypes and long commandsDifficulty: Easy Application: Shell The alias command is