Centralized BASH history with timestamps

For every Unix user, there comes a point where shell history suddenly becomes very relevant. You learn to consult it, then start recovering the last command, then switch to searching past commands history to save precious time normaly taken typing.
Shortly after such a point in your life, you'll probably want to enhance your shell history in two very common ways:
  1. Make sure every terminal window can update AND access your centralized shell history. So you run a command or two in one window, then type "history" anywhere else and see them two commands right there.
  2. Provide meanigful timeline, this is done with timestamps. Very simple and powerful change helps you see exactly when each command occured.

Here's how you achieve both of these massive improvents to your history in BASH. Just add this to /etc/bashrc on your Linux system:

export HISTTIMEFORMAT="%d.%m.%y %T "
export HISTCONTROL=ignoredups:erasedupsshopt -s histappend
export PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND$'\n'}history -a; history -c; history -r;"
export HISTCONTROL=ignoreboth

Using Dropbox with Unix

Although last week saw some pretty exciting developments in the cloud storage (Google Drive announcement and SkyDrive free 25Gb space), the truth is that Dropbox is still the king of the cloud storage hill – it's hands down the easiest to use and integrate.

I've been a Dropbox user for a few years now, but have started using it actively only in the last 12 months or so. It's been an invaluable tool for me thanks to its integration with 1Password, the password tool of my choice. Dropbox also helps with lots of day-to-day tasks and thats why I decided it's time to share some of the tips.

Having used Dropbox extensively on Windows systems (XP on laptop and Win7 on desktops), I've recently moved on to using Dropbox with my Mac OSX desktop and Linux hosting.

So here are the top tips for using Dropbox with Unix – each one does wonders for me and so I hope you like them as well.

Important: If you're not a Dropbox user yet, please use this link to sign up – it means I'll get a small bonus (extra 500MB to my free account) for referring you.

[Read more…]

Passwordless SSH with encrypted homedir in Ubuntu

Quite recently I came across a very interesting issue: while configuring passwordless SSH (it's public key based, so depending on you have it configured it may not be completely passwordless) access to some of my VPS servers, I found that the same keypair just wouldn't work on one of the servers.

Not only that, but the behaviour was quite bizzare: upon my first attempt to connect the public key would get rejected and a regular password would be requested by the ssh session. But once I successfully logged in with my password, any subsequent ssh connections would happily authenticate by my public key and would let me in without a problem.

Those of you using home dir encrypiton in Ubuntu are probably smiling right now! 🙂 But becase I have never consciously configured or used this feature, it took me a good few hours to troubleshoot the issue and come up with the fix.

[Read more…]

Use /proc/version to identify your Linux release

Hi everyone, I'm finally back from my holidays, and simply cannot wait to share some more Unix tips with all of you!

Today I'll talk a bit more about yet another way of learning version information about your Linux OS: the /proc/version file. I mentioned it briefly in one of the previous posts, but would like to finish the explanations.

What you can learn from /proc/version

This file will not show you the name of the actual OS release, but will instead give you specifics about the version of Linux kernel used in your distribution, and confirm the version of a GCC compiler used to build it.

[Read more…]

How To Monitor Linux Memory Usage with Watch Command

Hi all, today I'm going to teach you not one, but two really cool things in one post! First, I'll introduce you to advanced memory usage stats available on Linux systems through /proc/meminfo file, and then I'll explain the basics of using the watch command.

Memory usage with /proc/meminfo

As you know, quite a few Unix-like systems use the so-called pseudo file systems like /proc. It's not a real filesystem, but just a convenient representation of processes managed by your Unix OS. In Linux systems, this directory also contains quite a few files allowing you to access various information about your system. /proc/meminfo is one of such files, it gives you access to most of the memory usage stats.

[Read more…]