Commands by michelem (7)

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Find and delete oldest file of specific types in directory tree
This works on my ubuntu/debian machines. I suspect other distros need some tweaking of sort and cut. I am sure someone could provide a shorter/faster version.

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"

Create a new file

add a gpg key to aptitute package manager in a ubuntu system
when we add a new package to a aptitude (the debian package manager) we need to add the gpg, otherwise it will show warning / error for missing key

continuously check size of files or directories

zsh suffix to inform you about long command ending
make, find and a lot of other programs can take a lot of time. And can do not. Supppose you write a long, complicated command and wonder if it will be done in 3 seconds or 20 minutes. Just add "R" (without quotes) suffix to it and you can do other things: zsh will inform you when you can see the results. You can replace zenity with other X Window dialogs program.

Find the fastest server to disable comcast's DNS hijacking
Comcast is an ISP in the United States that has started hijacking DNS requests as a "service" for its customers. For example, in Firefox, one used to be able to do a quick "I'm Feeling Lucky" Google search by typing a single word into the URL field, assuming the word is not an existing domain when surrounded by www.*.com. Comcast customers never receive the correct NX (non-existent domain) error from DNS. Instead, they are shown a page full of advertising. There is a way to "opt out" from their service, but that requires having the account password and the MAC address of your modem handy. For me, it was easier just to set static DNS servers. But the problem is, which ones to choose? That's what this command answers. It'll show you the three _non-hijacked_ Comcast DNS servers that are the shortest distance away. Perhaps you don't have Comcast (lucky you!), but hopefully this command can serve as an example of using netselect to find the fastest server from a list. Note that, although this example doesn't show it, netselect will actually perform the uniq and DNS resolution for you. Requires: netselect, curl, sort, uniq, grep

Randomize lines in a file
Works in sort (GNU coreutils) 7.4, don't know when it was implemented but sometime the last 6 years.

Count number of files in subdirectories
For each directory from the current one, list the counts of files in each of these directories. Change the -maxdepth to drill down further through directories.

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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