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Mutes the speakers after an hour, in case you fall asleep watching a video...
Example: To store the function addfunction after you have defined it:
$ addfunction addfunction
QR codes are those funny square 2d bar codes that everyone seems to be pointing their smart phones at.
Try the following...
$ qrurl http://xkcd.com
Then open qr.*.png in your favorite image viewer.
Point your the bar code reader on your smart phone at the code, and you'll shortly be reading xkcd on your phone.
URLs are not the only thing that can be encoded by QR codes... short texts (to around 2K) can be encoded this way, although this function doesn't do any URL encoding, so unless you want to do that by hand it won't be useful for that.
Installs pip packages defining a proxy
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"
}
When dealing with system resource limits like max number of processes and open files per user, it can be hard to tell exactly what's happening. The /etc/security/limits.conf file defines the ceiling for the values, but not what they currently are, while
$ ulimit -a
will show you the current values for your shell, and you can set them for new logins in /etc/profile and/or ~/.bashrc with a command like:
$ ulimit -S -n 100000 >/dev/null 2>&1
But with the variability in when those files get read (login vs any shell startup, interactive vs non-interactive) it can be difficult to know for sure what values apply to processes that are currently running, like database or app servers. Just find the PID via "ps aux | grep programname", then look at that PID's "limits" file in /proc. Then you'll know for sure what actually applies to that process.
Needs Bash4. Found at http://stackoverflow.com/questions/2264428/converting-string-to-lower-case-in-bash-shell-scripting alongside a few other tricks.