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ls -qahlSr # list all files in size order - largest last
I find it useful, when cleaning up deleting unwanted files to make more space, to list in size order so I can delete the largest first. Note that using "q" shows files with non-printing characters in name. In this sample output (above), I found two copies of the same iso file both of which are immediate "delete candidates" for me.

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"

Copy a directory recursively without data/files

List your MACs address

Find the package that installed a command

Insert a colon between every two digits
I sometimes have large files of MAC addresses stored in a file, some databases need the information stored with the semicolon (makes for easier programming a device) others don't. I have a barcode to text file scanner which usually butchers MAC addresses so this was the fix> I initially did this in awk ;) awk '{for(i=10;i>=2;i-=2)$0=substr($0,1,i)":"substr($0,i+1);print}' mac_address_list

Displays the current time using HTTP
This command will show the current GMT time using HTTP. This might be useful if you just want to know what's the current human-readable and accurate-enough time, without changing the system time, using a simple command that would work regardless of the availability of NTP. Note: To get a quicker and more accurate response, replace google.com with your local NTP server. Also can be used as an alternative to the "htpdate" program: http://www.commandlinefu.com/commands/view/668/set-your-computers-clock-using-http-and-htp-http-time-protocol-when-ntpsntp-is-not-available

Deal with dot files safely

open path with your default GNOME program
Another step to bring cli and gui closer together: gnome-open It opens a path with the default (gui) application for its mime type. I would recommend a shorter alias like alias o=gnome-open More examples: $ gnome-open . [opens the current folder in nautilus / your default file browser] $ gnome-open some.pdf [opens some.pdf in evince / your default pdf viewer] $ gnome-open trash:// [opens the trash with nautilus] $ gnome-open http://www.commandlinefu.com [opens commandlinefu in your default webbrowser]

Remove a line in a text file. Useful to fix
In this case it's better do to use the dedicated tool


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