Share a console in linux with multiple users using screen

Sometimes you need to see or share some actions that you or somebody is doing in a remote server terminal (lx, mac..).
You can share your screen (join.me is a good solution) but the real way of doing it is to share you terminal / console.

The best way of doing this is using screen  multiuser option.
The procedure es staightforward:

1. open a screen session (-S give a session name):

screen -S screen-multi

2. activate multiuser mode

CTRL-A

 :multiuser on

3. the other user (connected to the same server) has to:

screen -x screen-multi

And thats it, both will see the same session and can write at the same time on it.

More detail about this procedure: http://ubuntuforums.org/showthread.php?t=299286

Show ping summary in MacOS terminal

ping can be used for a lot of things. I do use it a lot to test reachability and how my internet access is behaving.

Usually you just execute ping in your terminal and then hit Ctrl+C to see the summary as follows:

Hitting Ctrl+C will send an interrupt signal (SIGINT) to the process, making it to terminate and show ing the summary.

Once in a while you need to check a long ping run but don't want to stop it (because of the final stats). The way of doing it, is to send a SIGINFO signal hitting Ctrl+T while the process runs.

Check line 9 and 10 in the previous example:
and ping continues running!!!

References: Ping OS X Manual.

Mac OS X could not be installed on your computer

Today I upgraded my MacBook Pro operating system to OS X Lion, and was not so "cool". I get this error in the first attempt:

Install Failed

Mac OS X could not be installed on your computer

Mac OS X can't be installed on the disk Macintosh HD, because a
recovery system can't be created. 
Visit www.apple.com/support/no-recovery to learn more.

Going to www.apple.com/support/no-recovery is useless, will not help you at all (WTF Apple!!!)

To solve this issue you just have to:

1. Open Disk Utility in Application -> Utilities -> Disk Utility
2. Select your disk, in my case its: Machintosh HD
3. Click in "Repair Disk Permissions" and wait till it finishes
4. Start the upgrade again

Hope it helps!