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tail: watch a filelog
-f file(s) to be monitorized -n number of last line to be printed on the screen in this example, the content of two files are displayed

Temporarily ignore known SSH hosts
you may create an alias also, which I did ;-) alias sshu="ssh -o UserKnownHostsFile=/dev/null "

Monitor changed files into a log file, with day rotation, using fswatch (MacOS)
This command monitors changes in the current folder structure (subfolders included) and files, and log it into a hidden file in the same folder, called `.file_changes_YYMMDD.log`. Modify the `--exclude` parameters to define what should be skipped.

static compilation

Determine MAC address of remote host when you know its IP address
arping sends ARP requests to a neighboring host. This won't work if there is an ARP subnet gateway in the middle. If there is, you'll just get the gateway's MAC address not the host's address you are really trying to get to.

Virtualbox: setup hardware
where - memory 256 assign 256 Mb RAM - acpi on enable ACPI (mandatory if you use Winfog 2000 - ioapic off disable the IO APIC. Not useful if you use one CPU (on virtual machine or a 32 bit operative system). As ACPI, this switch is mandatory for Winbug 2000 - pae on enable the Phisical Address Extension how to use more than 4Gb of RAM on x86 CPU - hwvirtex on enables hardware virtualization extensions for microprocessors that have this feature (which should be also enabled in the BIOS of the motherboard) - nestedpaging on allows part of the processes of memory management hardware are made directly

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

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"

Adding Prefix to File name
Good old bracket expansion :-) For large numbers of files, "rename" will spare you the for-loop, or the find/exec...

Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.


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