Commands by JeremyYang (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" }

What is my public IP-address?
Very effective, use only DNS protocol. The @ part is optional if you already set opendns servers as default ns servers.

List of reverse DNS records for a subnet
This command uses nmap to perform reverse DNS lookups on a subnet. It produces a list of IP addresses with the corresponding PTR record for a given subnet. You can enter the subnet in CDIR notation (i.e. /24 for a Class C)). You could add "--dns-servers x.x.x.x" after the "-sL" if you need the lookups to be performed on a specific DNS server. On some installations nmap needs sudo I believe. Also I hope awk is standard on most distros.

find and delete empty dirs, start in current working dir

Pass TAB as field separator to sort, join, cut, etc.
Use this BASH trick to create a variable containing the TAB character and pass it as the argument to sort, join, cut and other commands which don't understand the \t notation. $ sort -t $'\t' ... $ join -t $'\t' ... $ cut -d $'\t' ...

Show all available colors on your terminal.
Using perl and tput, show all the colors with numbers that your actual $TERM can handle. If want to remove the numbers at beginning of new line, it should be something like this: $perl -E 'say `tput setb $_`," "x `tput cols`, `tput sgr0` for 0 .. (`tput colors` - 1)'

Check if your desired password is already available in haveibeenpwnd database. This command uses the API provided by HIBP

Create backup copy of file, adding suffix of the date of the file modification (NOT today's date)
When I go to change a configuration file I always like to make a backup first. You can use "cp -p" to preserve the modification time, but it gets confusing to have file.prev, file.prev2, etc. So I like to add a YYMMDD suffix that shows when the file was last changed. "stat -c %Y" gives you the modification time in epoch seconds, then "date -d @" converts that to whatever format you specify in your "+format" string.

ASCII webcam live stream video using mplayer
Mplayer starts a webcam capture using ASCII art. Only mplayer required

SSH Auto-login with password
You need to install "sshpass" for this to work. apt-get install sshpass

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