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Recursively list all of the files in a directory, group them by extension and calculate the average of the file sizes in each group
Here's an annotated version of the command, using full-names instead of aliases. It is exactly equivalent to the short-hand version. # Recursively list all the files in the current directory. Get-ChildItem -Recurse | # Filter out the sub-directories themselves. Where-Object { return -not $_.PsIsContainer; } | # Group the resulting files by their extensions. Group-Object Extension | # Pluck the Name and Count properties of each group and define # a custom expression that calculates the average of the sizes # of the files in that group. # The back-tick is a line-continuation character. Select-Object ` Name, Count, @{ Name = 'Average'; Expression = { # Average the Length (sizes) of the files in the current group. return ($_.Group | Measure-Object -Average Length).Average; } } | # Format the results in a tabular view, automatically adjusted to # widths of the values in the columns. Format-Table -AutoSize ` @{ # Rename the Name property to something more sensible. Name = 'Extension'; Expression = { return $_.Name; } }, Count, @{ # Format the Average property to display KB instead of bytes # and use a formatting string to show it rounded to two decimals. Name = 'Average Size (KB)'; # The "1KB" is a built-in constant which is equal to 1024. Expression = { return $_.Average / 1KB }; FormatString = '{0:N2}' }

Backup all starred repositories from Github

Ring the system bell after finishing a long script/compile
This will ring the system bell once if your script exits successfully and twice if it fails. So you can go look at something else and it will alert you when done. Don't forget to use 'xset b [vol [pitch [duration]]]' to get the bell to sound the way you want.

one-liner mpc track changer using dmenu
Add a [fluxbox] binding in your key file then this command provides a dmenu selector for the next track to play

Recurse through directories easily
This is a simple case of recursing through all directories, adding the '.bak' extension to every file. Of course, the 'cp $file $file.bak' could be any code you need to apply to your recursion, including tests, other functions, creating variables, doing math, etc. Simple and clean recursion.

Monitor all DNS queries made by Firefox

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"

Umount only the NFS related to 'string'
Sometimes, you have a lot of NFS in the server and you can't or shouldn't use umount -a. Whis this command, you only umount the fs related to the 'string'

Find all active ip's in a subnet

show the real times iso of epochs for a given column
When you have one of those (log)files that only has epoch for time (since no one will ever look at them as a date) this is a way to get the human readable date/time and do further inspection. Mostly perl-fu :-/


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