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Format partition with ext4 but without a journal
For slow flash memory (cheap thumb drive), ext4 is the fastest stable file system for all use cases with no relevant exception: http://www.linuxplanet.com/linuxplanet/tutorials/7208/1 Since we can usually dispense with the benefits of a journal for this type of storage, this is a way to achieve the least awful I/O-speed. Disabling the journal for an existing ext4 partition can be achieved using $ tune2fs -O ^has_journal /dev/sdXN Note that it is often recommended to format removable flash media with ext2, due to the lack of a journal. ext4 has many advantages over ext2 even without the journal, with much better speed as one of the consequences. So the only usecase for ext2 would be compatibility with very old software.

Get a range of SVN revisions from svn diff and tar gz them
Handy when you need to create a list of files to be updated when subversion is not available on the remote host. You can take this tar file, and upload and extract it where you need it. Replace M and N with the revisions specific to yours. Make sure you do this from an updated (svn up) working directory.

matrix in your term
-a : Asynchronous scroll -b : Bold characters on -x : X window mode, use if your xterm is using mtx.pcf

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Download SSL/TLS pem format cert from https web host

Show UDID of iPhone
Display the serial of the iPhone (aka UDID).

ls -qaltr # list directory in chronological order, most recent files at end of list
I find it very handy to be able to quickly see the most recently modified/created files in a directory. Note that the "q" option will reveal any files with non-printable characters in their filename.

check open ports without netstat or lsof

mount an iso
mounts an ISO file to a directory on the target file system

Split and join with split and cat.
`split -b 1k file` splits files into 1k chunks. Rejoin them with `cat x* > file`.


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