Commands by paulochf (4)

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Get an IP address out of fail2ban jail
Removes an iptables rule created by fail2ban. This example shows how to remove a rule for an IP from the fail2ban-SSH chain. Can be used for any service monitored by fail2ban. For more on fail2ban, see http://www.fail2ban.org/wiki/index.php/Main_Page

Gives you what's between first string and second string included.
If the file content is : - Blah blah blah ABC hello blah blah blah bloh bloh bloh DEF Bah bah bah - You'll get: - ABC hello blah blah blah bloh bloh bloh DEF

Find out how old a web page is
I used to use the Firefox "View page info" feature a lot to determine how stale the web page I was looking at was. Now that I use mostly Chrome I miss that feature, so here is a command line alternative using wget. The -S says to display the server response, the --spider says to not download any files/pages, just fetch the header. The output goes to stderr, so to grep it you use 2>&1 to combine the stderr stream with stdout, the pipe that to grep for Last-Modified. You can use curl instead if you have it installed, like this: $ curl --head -s http://osswin.sourceforge.net | grep Mod

Recursively chmod all dirs to 755 and all files to 644

Get the full path to a file
Useful in scripts when the file is passed in as an argument. Eg. $ filepath=$(realpath $1)

Get Shellcode from ARM Binaries
Getting shellcode from ARM binaries - @OsandaMalith

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"

Find and display most recent files using find and perl
This pipeline will find, sort and display all files based on mtime. This could be done with find | xargs, but the find | xargs pipeline will not produce correct results if the results of find are greater than xargs command line buffer. If the xargs buffer fills, xargs processes the find results in more than one batch which is not compatible with sorting. Note the "-print0" on find and "-0" switch for perl. This is the equivalent of using xargs. Don't you love perl? Note that this pipeline can be easily modified to any data produced by perl's stat operator. eg, you could sort on size, hard links, creation time, etc. Look at stat and just change the '9' to what you want. Changing the '9' to a '7' for example will sort by file size. A '3' sorts by number of links.... Use head and tail at the end of the pipeline to get oldest files or most recent. Use awk or perl -wnla for further processing. Since there is a tab between the two fields, it is very easy to process.

Show drive names next to their full serial number (and disk info)
As of this writing, this requires a fairly recent version of util-linux, but is much simpler than the previous alternatives. Basically, lsblk gives a nice, human readable interface to all the blkid stuff. (Of course, I wouldn't recommend this if you're going to be parsing the output.) This command takes all the fun out of the previous nifty pipelines, but I felt I ought to at least mention it as an alternative since it is the most practical.

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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