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Downmix first audio stream from 7.1 to 5.1 keeping all other streams
Useful for Roku which does not support 7.1. Useful resources: - https://trac.ffmpeg.org/wiki/Map - https://trac.ffmpeg.org/wiki/Encode/HighQualityAudio - https://superuser.com/questions/852400/properly-downmix-5-1-to-stereo-using-ffmpeg

Get absolut path to your bash-script
Another way of doing it that's a bit clearer. I'm a fan of readable code.

Setting global redirection of STDERR to STDOUT in a script
You have a script where =ALL= STDERR should be redirected to STDIN and you don't want to add "2>&1" at the end of each command... E.G.: $ ls -al /foo/bar 2>&1 Than just add this piece of code at the beginning of your script! I hope this can help someone. :)

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"

direct a single stream of input (ls) to multiple readers (grep & wc) without using temporary files

Beep siren
Infinitely plays beeps with sinusoidally changing sound frequency. Ideal for alarm on an event.

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"

Compare a remote file with a local file

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

'hpc' in the shell - starts a maximum of n compute commands modulo n controlled in parallel, using make
this oneliner uses make and it's jobserver for parallel execution of your script. The '-j' flag for make defines number of subprocesses to launch, '-f' tells make use stdin instead of Makefile. Also make have neat flag '-l', which "Specifies that no new jobs (commands) should be started if there are others jobs running and the load is at least load (a floating-point number)." Also you can use plain Makefile, for better readability: targets = $(subst .png,.jpg,$(wildcard *.png)) $(targets): echo convert $(subst .jpg,.png,$@) $@ all : $(targets)


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