Commands using tr (338)

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Convert unix timestamp to date
The "-d" option for gnu's "date" command can calculate positive or negative offset from any time, including "now". You can even specify a source timezone (the output timezone can be set with the TZ environment variable). Useful! Fun! Not very well documented!

Set your profile so that you resume or start a screen session on login
From screen's manpage: "Attach here and now. In detail this means: If a session is running, then reattach. If necessary detach and logout remotely first. If it was not running create it and notify the user. This is the author's favorite." Toss this in your ~/.bash_profile so that you never have that "oh crap" moment where you wanted to run something in screen and didn't.

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"

quickest (i blv) way to get the current program name minus the path (BASH)
Useful in shell scripts when you're trying to get the shell script name without the full path - and easier than awking or cutting. Bash pattern matching and variable manip is fun.

drop first column of output by piping to this

Remove specific versions of old kernels (Ubuntu/Debian)
If, for example, you want to remove all kernels and headers but the last three versions, you can't use one of that magic all-in-one "remove old stuff" commands. With this simple but elegant command you can remove a range of versions, or a list of versions with e.g. {14,16,20}.

Print trending topics on Twitter

Find usb device
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

Find the 10 users that take up the most disk space

Drop or block attackers IP with null routes
Someone might attack on your system. You can drop attacker IP using IPtables. However, you can use route command to null route unwanted traffic. A null route (also called as blackhole route) is a network route or kernel routing table entry that goes nowhere. Matching packets are dropped (ignored) rather than forwarded, acting as a kind of very limited firewall. The act of using null routes is often called blackhole filtering.


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