Commands by jordan1919 (0)

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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" }

Kill any lingering ssh processes

Combines an arbitrary number of transparent png files into one file
This one liner; combines all sequentially numbered files; in this example IMG_0001.png to IMG_1121.png by generating the shell script, making the shell script executable and then running the shell script to combine the 1121 png into a single png file named _final.png tested on Mac OS X 10.6.3 with ImageMagick 6.5.8-0 2009-11-22 Q16 http://www.imagemagick.org

Simple example of the trap command

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" }

Perl one-liner to determine number of days since the Unix epoch
There are some environments that use this value for password and account expiration. It's helpful to be able to quickly determine the number of days since the Unix epoch (dse) when working directly with the configuration files as an administrator.

check open ports without netstat or lsof

Use a decoy while scanning ports to avoid getting caught by the sys admin :9
Scan for open ports on the target device/computer (192.168.0.10) while setting up a decoy address (192.168.0.2). This will show the decoy ip address instead of your ip in targets security logs. Decoy address needs to be alive. Check the targets security log at /var/log/secure to make sure it worked.

add an mp3 audio track to a video

rsync directory tree including only files that match a certain find result.
'-mtime -10' syncs only files newer 10 days (-mtime is just one example, use whatever find expressions you need) printf %P: File's name with the name of the command line argument under which it was found removed. this way, you can use any src directory, no need to cd into your src directory first. using \\0 in printf and a corresponding --from0 in rsync ensures that even filenames with newline characters work (thanks syssyphus for #3808). both, #1481 and #3808 just work if you either copy the current directory (.) , or the filesystem root (/), otherwise the output from find and the source dir from rsync just don't match. #7685 works with an arbitrary source directory.

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