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run command on a group of nodes in parallel
Parallel is from https://savannah.nongnu.org/projects/parallel/ Other examples would be: (echo foss.org.my; echo www.debian.org; echo www.freenetproject.org) | parallel traceroute seq -f %04g 0 9999 | parallel -X rm pict{}.jpg

output length of longest line
If your wc does not have the -L option, you can use awk.

View files opened by a program on startup and shutdown
Run this before you run a command in order to see what the command does as it starts. The -c flag is useful here as the PID is unknown before startup. All config files, libraries, logs, ports, etc used by the command as it starts up, (and shuts down) will be captured at 1s intervals and written to a file. Useful for debugging etc.

List all authors of a particular git project
List everyone who committed to a particular project, listed alphabetically. To list by commits, add -n to the shortlog.

Awk: Perform a rolling average on a column of data
Sometimes jittery data hides trends, performing a rolling average can give a clearer view.

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

List only directory names
This command would be useful when it is desirable to list only the directories. Other options Hidden directory $ ls -d .*/ Other path $ ls -d /path/to/top/directory/.*/ Long format: $ ls -ld */

change user & preserver environment (.bashrc&co)

Alert on high ping to know if it's really laggy while playing
Online games have pretty good lag compensation nowadays, Sometimes though, you really want to get some warning about your latency, e.g. while playing Diablo III in Hardcore mode, so you know when to carefully quit the game b/c your flatmate started downloading all his torrents at once. This is done on Darwin. On Linux/*nix you would need to find another suitable command instead of `say` to spell out your latency. And I used fping because it's a little bit easier to get the latency value needed. Something similar with our regular ping command could look like this: $ while :; do a=$(ping -c1 google.com | grep -o 'time.*' | cut -d\= -f2 | cut -d\ -f1 | cut -b1-4); [[ $a > 40 ]] && say "ping is $a"; sleep 3; done

Change Windows Domain password from Linux
If you use Linux in a Windows domain and there are N days to expiry, this is how you can change it without resorting to a windows machine.


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