Commands by pebkac (4)

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Advanced python tracing
Trace python statement execution and syscalls invoked during that simultaneously

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"

print shared library dependencies
May be used on (embedded) systems lack ldd

Output the content of your Active Directory in a CSV file

Replace spaces in filenames with underscores

Create a directory and go inside it
$_ expands to the last argument of the last command that was executed

Backup with versioning
Apart from an exact copy of your recent contents, also keep all earlier versions of files and folders that were modified or deleted. Inspired by EVACopy http://evacopy.sourceforge.net

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

Enable programmable bash completion in debian lenny
The really awesome bash completion in debian seems to be an extra package now, which has to be installed. After sourcing /etc/bash_completion it completes almost everything (package names in apt... etc) :-) To make this permanent, put something like this in your .bashrc: if [ -f /etc/bash_completion]; then source /etc/bash_completion fi

Display IP : Count of failed login attempts
The lastb command presents you with the history of failed login attempts (stored in /var/log/btmp). The reference file is read/write by root only by default. This can be quite an exhaustive list with lots of bots hammering away at your machine. Sometimes it is more important to see the scale of things, or in this case the volume of failed logins tied to each source IP. The awk statement determines if the 3rd element is an IP address, and if so increments the running count of failed login attempts associated with it. When done it prints the IP and count. The sort statement sorts numerically (-n) by column 3 (-k 3), so you can see the most aggressive sources of login attempts. Note that the ':' character is the 2nd column, and that the -n and -k can be combined to -nk. Please be aware that the btmp file will contain every instance of a failed login unless explicitly rolled over. It should be safe to delete/archive this file after you've processed it.

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