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Two command output
Summarize established connections after netstat output. Using tee and /dev/stderr you can send one command output to terminal before executing wc so you can summarize at the bottom of the output.

Disable sleep mode via cli and systemd (Centos, Debian Ubuntu?)
This causes computer to never power off or go into sleep mode. Disables sleep mode linux.

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" }

Create multiple mp4 files using avidemux
Convert multiple files using avidemux. Version updated (thanks to the guys who helped me giving me hints about how to improve the command). Works with files whose name contains blank characters. One of the reasons why I love open source: everyone can take something "done" and improve it to make it better! If u have suggestions, please let me know.

Keep a copy of the raw Youtube FLV,MP4,etc stored in /tmp/
Certain Flash video players (e.g. Youtube) write their video streams to disk in /tmp/ , but the files are unlinked. i.e. the player creates the file and then immediately deletes the filename (unlinking files in this way makes it hard to find them, and/or ensures their cleanup if the browser or plugin should crash etc.) But as long as the flash plugin's process runs, a file descriptor remains in its /proc/ hierarchy, from which we (and the player) still have access to the file. The method above worked nicely for me when I had 50 tabs open with Youtube videos and didn't want to have to re-download them all with some tool.

Open files in a split windowed Vim
-o acts like :spit. Use -O (capital o) for side-by-side like :vsplit. Use vim -d or vimdiff if you need a diff(1) comparison. To split gnu Screen instead of vim, use ^A S for horizontal, ^A | for vertical.

burn an ISO image to writable CD
Does life get much easier? Read up about wodim for an understanding of its origins in relation to the older `cdrecord` utility

Make a thumbnail image of first page of a PDF.
convert is included in ImageMagick. Don't forget the [X] (where X is the page number). [0] is the first page of the PDF.

Make .bashrc function to backup the data you changed last houres
The original overwrites any previous backups, and only saves exactly the last hours worth, but not 1 hour + 1 minute. This version creates or appends files, and backs up everything since the last backup (using the backups timestamp as the reference), plus it uses TMPDIR if set.

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"


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