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recursively change file name from uppercase to lowercase (or viceversa)
or, to process a single directory: $ for f in *; do mv $f `echo $f |tr '[:upper:]' '[:lower:]'`; done

Duplicate several drives concurrently
If you have some drive imaging to do, you can boot into any liveCD and use a commodity machine. The drives will be written in parallel. To improve efficiency, specify a larger block size in dd: $dd if=/dev/sda bs=64k | tee >(dd of=/dev/sdb bs=64k) | dd of=/dev/sdc bs=64k To image more drives , insert them as additional arguments to tee: $dd if=/dev/sda | tee >(dd of=/dev/sdb) >(dd of=/dev/sdc) >(dd of=/dev/sdd) | dd of=/dev/sde

Awk: Perform a rolling average on a column of data
Sometimes jittery data hides trends, performing a rolling average can give a clearer view.

Readd all files is missing from svn repo
When working on a big proeject with SVN, you create quite much files, for now! Can just sit here and type svn add for all of them! svn status will return a list of all of file which get ?(not add), "M"(Modified), "D"(Deleted)! This code just grep "?" flag, then add it into SVN again!

Create a file of a given size in linux
If you're trying to create a sparse file, you can use dd by 'skip'ing to the last block instance. ls -ls shows the actual size vs. the reported size

Video thumbnail
Faster thumbnail creation than '-itsoffset' $ffmpeg -itsoffset -4 -i test.avi -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 test.jpg

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Copy specific files recursively using the same tree organization.
This command has been used to overwrite corrupted "entries" files of a corrupted subversion working copy. Note the --files-from input format.

send a circular

Create more threads with less stack space
default stack size is 10M. This makes your multithread app filling rapidly your memory. on my PC I was able to create only 300thread with default stack size. Lower the default stack size to the one effectively used by your threads, let you create more. ex. putting 64k I was able to create more than 10.000threads. Obviously ...your thread shouldn't need more than 64k ram!!!


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