Lazy Linux: 10 essential tricks for admins

The best systems administrators are set apart by their efficiency. And if an efficient systems administrator can do a task in 10 minutes that would take another mortal two hours to complete, then the efficient systems administrator should be rewarded (paid more) because the company is saving time, and time is money, right?
The trick is to prove your efficiency to management. While I won't attempt to cover that trick in this article, I will give you 10 essential gems from the lazy admin's bag of tricks. These tips will save you time—and even if you don't get paid more money to be more efficient, you'll at least have more time to play Halo.

Trick 1: Unmounting the unresponsive DVD drive
The newbie states that when he pushes the Eject button on the DVD drive of a server running a certain Redmond-based operating system, it will eject immediately. He then complains that, in most enterprise Linux servers, if a process is running in that directory, then the ejection won't happen. For too long as a Linux administrator, I would reboot the machine and get my disk on the bounce if I couldn't figure out what was running and why it wouldn't release the DVD drive. But this is ineffective.

Here's how you find the process that holds your DVD drive and eject it to your heart's content: First, simulate it. Stick a disk in your DVD drive, open up a terminal, and mount the DVD drive:

# mount /media/cdrom
# cd /media/cdrom
# while [ 1 ]; do echo "All your drives are belong to us!"; sleep 30; done

Now open up a second terminal and try to eject the DVD drive:

# eject

You'll get a message like:

umount: /media/cdrom: device is busy

Before you free it, let's find out who is using it.

# fuser /media/cdrom

You see the process was running and, indeed, it is our fault we can not eject the disk.

Now, if you are root, you can exercise your godlike powers and kill processes:

# fuser -k /media/cdrom

Boom! Just like that, freedom. Now solemnly unmount the drive:

# eject

fuser is good.

Trick 2: Getting your screen back when it's hosed

Try this:

# cat /bin/cat

Behold! Your terminal looks like garbage. Everything you type looks like you're looking into the Matrix. What do you do?
You type reset. But wait you say, typing reset is too close to typing reboot or shutdown. Your palms start to sweat—especially if you are doing this on a production machine.
Rest assured: You can do it with the confidence that no machine will be rebooted. Go ahead, do it:

# reset

Now your screen is back to normal. This is much better than closing the window and then logging in again, especially if you just went through five machines to SSH to this machine.

Trick 3: Collaboration with screen
David, the high-maintenance user from product engineering, calls: "I need you to help me understand why I can't compile supercode.c on these new machines you deployed."
"Fine," you say. "What machine are you on?"
David responds: " Posh." (Yes, this fictional company has named its five production servers in honor of the Spice Girls.) OK, you say. You exercise your godlike root powers and on another machine become David:

# su - david

Then you go over to posh:

# ssh posh

Once you are there, you run:

# screen -S foo

Then you holler at David:
"Hey David, run the following command on your terminal: # screen -x foo."
This will cause your and David's sessions to be joined together in the holy Linux shell. You can type or he can type, but you'll both see what the other is doing. This saves you from walking to the other floor and lets you both have equal control. The benefit is that David can watch your troubleshooting skills and see exactly how you solve problems.
At last you both see what the problem is: David's compile script hard-coded an old directory that does not exist on this new server. You mount it, recompile, solve the problem, and David goes back to work. You then go back to whatever lazy activity you were doing before.
The one caveat to this trick is that you both need to be logged in as the same user. Other cool things you can do with the screen command include having multiple windows and split screens. Read the man pages for more on that.
But I'll give you one last tip while you're in your screen session. To detach from it and leave it open, type: Ctrl-A D . (I mean, hold down the Ctrl key and strike the A key. Then push the D key.)
You can then reattach by running the screen -x foo command again.

Trick 4: Getting back the root password

Read more: IBM

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