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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"

Update a tarball
This will update the tarball, adding files that have changed since the last update. This assumes that the tarball is in the same directory as the files being archived. N.B. This command can't be used on compressed tarballs. N.B. This will add the updated files to the tarball, so that the tarball will have two versions of each file. This will make the tarball larger, but doesn't have any other significant effect.

copies 20 most recently downloaded mp3 files (such as from Miro) into a directory
Change ~/tmp to the destination directory, such as your mounted media. Change -n20 to whatever number of files to copy. It should quit when media is full. I use this to put my most recently downloaded podcasts onto my phone.

Bash scripts encryption and passphrase-protection
This function will encrypt a bash script and will only execute it after providing the passphrase. Requires mcrypt to be installed on the system.

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.

Get the full path of a bash script's Git repository head.
Rather than complicated and fragile paths relative to a script like "../../other", this command will retrieve the full path of the file's repository head. Safe with spaces in directory names. Works within a symlinked directory. Broken down: $cd "$(dirname "${BASH_SOURCE[0]}")" temporarily changes directories within this expansion. Double quoted "$(dirname" and ")" with unquoted ${BASH_SOURCE[0]} allows spaces in the path. $git rev-parse --show-toplevel gets the full path of the repository head of the current working directory, which was temporarily changed by the "cd".

Massive change of file extension (bash)
Change the file extension in batch. Useful to create output file names with same input name but distinct extension by including logic inside the loop

Stop Flash from tracking everything you do.
Brute force way to block all LSO cookies on a Linux system with the non-free Flash browser plugin. Works just fine for my needs. Enjoy.

Convert images (jpg, png, ...) into a PDF
Converts images (maybe from scans) into a PDF

Convert PNG to GIF
(relies on 'imagemagick') Convert all .png files to .gif. This can also go the other way if you reverse the file extensions in the command, e.g.: $ for file in *.gif; do convert "$file" "$(basename $file .gif).png"; done If the file is named 'example1.png' it will be named 'example1.gif' when it is complete.


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