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log your PC's motherboard and CPU temperature along with the current date
Uses the data in the /proc system, provided by the acpid, to find out the CPU temperature. Can be run on systems without lm-sensors installed as well.

extract email addresses from some file (or any other pattern)

Open a manpage in the default (graphical) web browser
An easy alias for opening a manpage, nicely HTML formatted, in your set internet browser. If you get a "command exited with status 3" error you need to install groff.

Benchmark SQL Query
Benchmark a SQL query against MySQL Server. The example runs the query 10 times, and you get the average runtime in the output. To ensure that the query does not get cached, use `RESET QUERY CACHE;` on top in the query file.

preserve disk; keep OS clean
if you use disk-based swap then it can defeat the purpose of this function.

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"

Use a var with more text only if it exists
See "Parameter Expansion" in the bash manpage. They refer to this as "Use Alternate Value", but we're including the var in the at alternative.

Is it a terminal?
Oddly, the isatty(3) glibc C call doesn't have a direct analogue as a command 'isatty(1)'. All is not lost as you can use test(1). For example, your script might be run from a tty or from a GUI menu item but it needs to get user-input or give feedback. Now your script can test STDIN with 'isatty 0' or STDOUT with 'isatty 1' and use xmessage(1) if the tty is not available. The other way to test for this is with 'tty -s' - but that's only for STDIN.

List the binaries installed by a Debian package
GNU grep's perl-compatible regular expression(PCRE).

find and delete empty dirs, start in current working dir


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