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Count the total amount of hours of your music collection
First the find command finds all files in your current directory (.). This is piped to xargs to be able to run the next shell pipeline in parallel. The xargs -P argument specifies how many processes you want to run in parallel, you can set this higher than your core count as the duration reading is mainly IO bound. The -print0 and -0 arguments of find and xargs respectively are used to easily handle files with spaces or other special characters. A subshell is executed by xargs to have a shell pipeline for each file that is found by find. This pipeline extracts the duration and converts it to a format easily parsed by awk. ffmpeg reads the file and prints a lot of information about it, grep extracts the duration line. cut and sed cut out the time information, and tr converts the last . to a : to make it easier to split by awk. awk is a specialized programming language for use in shell scripts. Here we use it to split the time elements in 4 variables and add them up.

list block devices
Shows all block devices in a tree with descruptions of what they are.

Stop Flash from tracking everything you do.
Brute force way to block all LSO cookies on a Linux system with the non-free Flash browser plugin. Works just fine for my needs. Enjoy.

Copy ssh keys to user@host to enable password-less ssh logins.
Alternative for machines without ssh-copy-id

Select and Edit a File in the Current Directory
This command displays a simple menu of file names in the current directory. After the user made a choice, the command invokes the default editor to edit that file. * Without the break statement, the select command will loop forever * Setting the PS3 prompt is optional * If the user types an invalid choice (such as the letter q), then the variable $f will become an empty string. * For more information, look up the bash's select command

Convert all old SVN repositories in one directory to new format

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"

list all file extensions in a directory
A shorter version

Fulltext search in multiple OCR'd pdfs

Insert a line at the top of a text file without sed or awk or bash loops
Just use '-' to use STDIN as an additional input to 'cat'


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