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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" }

check open ports without netstat or lsof

Create a tar file with the current date in the name.
Same, but count of signs is little less :) .

Listing only one repository with yum
How to list just one repo with yum. First I disable all repo, second I enable just the repo that I want to list.

Google voice recognition "API"
The FLAC audio must be encoded at 16000Hz sampling rate (SoX is your friend). Outputs a short JSON string, the actual speech is in the hypotheses->utterance, the accuracy is stored in hypotheses->confidence (ranging from 0 to 1). Google also accepts audio in some special speex format (audio/x-speex-with-header-byte), which is much smaller in comparison with losless FLAC, but I haven't been able to encode such a sample.

tar the current directory wihtout the absolute path
tars the current directory (and its children) in an archive of the same name (plus ".tar" :)) in the parent directory without the absolute path, so that when the archive is extracted, only the current directory name is created for the path. Assumes bash/zsh.

list unique file extensions recursively for a path, include extension frequency stats
Get the longest match of file extension (Ex. For 'foo.tar.gz', you get '.tar.gz' instead of '.gz')

Extracting frames from a video as jpeg files
This command extracts 10 seconds worth of frames, starting from 00:15:45 position, from filename.avi and stores them into out_frames folder as jpeg files. Subtitles are turned off with -sid 999 option.

Resample a WAV file with sox
Change the sample rate with sox, the swiss army knife of sound processing.

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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