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One person does `mkfifo foo; script -f foo' and another can supervise real-time what is being done using `cat foo'.
It takes over 5 seconds to scan a single port on a single host using nmap
$ time (nmap -p 80 192.168.1.1 &> /dev/null)
real 0m5.109s
user 0m0.102s
sys 0m0.004s
It took netcat about 2.5 minutes to scan port 80 on the class C
$ time (for NUM in {1..255} ; do nc -w 1 -z -v 192.168.1.${NUM} 80 ; done &> /dev/null)
real 2m28.651s
user 0m0.136s
sys 0m0.341s
Using parallel, I am able to scan port 80 on the entire class C in under 2 seconds
$ time (seq 1 255 | parallel -j255 'nc -w 1 -z -v 192.168.1.{} 80' &> /dev/null)
real 0m1.957s
user 0m0.457s
sys 0m0.994s
Even faster without the need for cut... :)
list the top 15 folders by decreasing size in MB
works best in a shell script run at startup. It will ping localhost once and output to null, after it does that, acpi is called for temperature in fahrenheit and piped through to another loop that feeds notify-send for a tooltip. After waiting five minutes, it will start over.
Say you just typed a long command like this:
$ rsync -navupogz --delete /long/path/to/dir_a /very/long/path/to/dir_b
but you really want to sync dir_b to dir_a. Instead of rewriting all the command line, just type followed by , and your command line will read
$ rsync -navupogz --delete /very/long/path/to/dir_b /long/path/to/dir_a
This lets you replace a file or directory and quickly revert if something goes wrong. For example, the current version of a website's files are in public_html. Put a new version of the site in public_html~ and execute the command. The names are swapped. If anything goes wrong, execute it again (up arrow or !!).
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