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small CPU benchmark with PI, bc and time.
$ # 4 cores with 2500 pi digits $ CPUBENCH 4 2500 $. $ every core will use 100% cpu and you can see how fast they calculate it. $ if you do 50000 digitits and more it can take hours or days

Remove comments from files
Use sed to remove comments from a file. In this example the comments begin with #. The command '/^#/d' remove line starting with #. The command 's/#.*$//' remove comments at end of lines.

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Print lines in a text file with numbers in first column higher or equal than a value
A text file contains thousands of numbers. This command prints lines were the number is greater or equal than a specified value (134000000).

a function to find the fastest DNS server
http://public-dns.info gives a list of online dns servers. you need to change the country in url (br in this url) with your country code. this command need some time to ping all IP in list.

Selecting a random file/folder of a folder
Also looks in subfolders

strip config files of comments
some configuration files, particularly those installed by default as part of a package, have tons of comment lines, to help you know what's possible to configure, and what it means. That's nice, but sometimes you just want to see what specifically what _has_ been configured. That's when I use the above snippet, which I save as a bash alias 'nocom' (for 'no comments'). Apache default config files are perfect examples of when/why this script is handy.

Check every URL redirect (HTTP status codes 301/302) with curl
curl -sLkIv --stderr - https://t.co/2rQjHfptZ8 -s: silences the output when piped to a different command -L: follow every redirect -k: ignores certificate errors -I: just request the headers -v: be verbose --stderr - : redirect stderr to stdout https://t.co/2rQjHfptZ8: URL to check for redirects piped to grep -i location: -i: grep target text ignoring case location: : greps every string containing "location:" piped to awk {'print $3'} prints the third column in every string piped to sed '/^$/d' removes blank lines

Create a backdoor on a machine to allow remote connection to bash
My netcat (nc-1.84-10.fc6) doesn't have the -e option, so I have to do it like this. Of course, instead of bash, you can use any executable, including scripts.


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