c0d3 :: j0rg3

A collection of tips, tricks and snips. A proud Blosxom weblog. All code. No cruft.

Sat, 25 Jan 2014

Network-aware Synergy client

My primary machines are *nix or BSD variants, though I certainly have some Windows-based rigs also. Today we’re going to share some love with Windows 7 and PowerShell.

One of my favorite utilities is Synergy. If you’re not already familiar it allows to you seamlessly move from the desktop of one computer to another with the same keyboard and mouse. It even supports the clipboard so you might copy text from a GNU/Linux box and paste it in a Windows’ window. Possibly, they have finished adding drag and drop to the newer versions. I am not sure because I run a relatively old version that is supported by all of the machines that I use regularly.

What’s the problem, then? The problem was that I was starting my Synergy client by hand. Even more disturbing, I was manually typing the IP address at work and at home, twice or more per weekday. This behavior became automated by my brain and continued for months unnoticed. But this is no kind of life for a geek such as myself, what with all this superfluous clicking and tapping!

Today, we set things right!

In my situation, the networks that I use happen to assign IP addresses from different subnets. If you’ve not the convenience of that situation then you might need to add something to the script. Parsing an ipconfig/ifconfig command, you could possibly use something like the Default Gateway or the Connection-specific DNS Suffix. Alternatively, you could check for the presence of some network share, a file on server or anything that would allow you to uniquely identify the surroundings.

As I imagined it, I wanted the script to accomplish the following things

  • see if Synergy is running (possibly from the last location), if so ask if we need to kill it and restart so we can identify a new server
  • attempt to locate where we are and connect to the correct Synergy server
  • if the location is not identified, ask whether to start the Synergy client

This is how I accomplished that task:

# [void] simply supresses the noise made loading 'System.Reflection.Assembly'
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")

# Define Synergy server IP addresses
$synergyServerWork = "192.168.111.11"
$synergyServerHome = "192.168.222.22"

# Define partial IP addresses that will indicate which server to use
$synergyWorkSubnets = "192.168.111", "192.168.115"
$synergyHomeSubnets = "192.168.222", "192.168.225"

# Path to Synergy Client (synergyc)
$synergyClientProgram = "C:\Program Files\Synergy\synergyc.exe"

# Path to Syngery launcher, for when we cannot identify the network
$synergyLauncherProgram = "C:\Program Files\Synergy\launcher.exe"

# Remove path and file extension to give us the process name
$processName = $synergyClientProgram.Substring( ($synergyClientProgram.lastindexof("\") + 1), ($synergyClientProgram.length - ($synergyClientProgram.lastindexof("\") + 5) ))

# Grab current IP address
$currentIPaddress = ((ipconfig | findstr [0-9].\.)[0]).Split()[-1]

# Find the subnet of current IP address
$location = $currentIPaddress.Substring(0,$currentIPaddress.lastindexof("."))


function BalloonTip ($message)
{
# Pop-up message from System Tray
$objNotifyIcon = New-Object System.Windows.Forms.NotifyIcon
$objNotifyIcon.Icon = [System.Drawing.Icon]::ExtractAssociatedIcon($synergyClientProgram)
$objNotifyIcon.BalloonTipText = $message
$objNotifyIcon.Visible = $True
$objNotifyIcon.ShowBalloonTip(15000)
}


#main

# If Synergy client is already running, do we need to restart it?
$running = Get-Process $processName -ErrorAction SilentlyContinue
if ($running) {
$answer = [System.Windows.Forms.MessageBox]::Show("Synergy is running.`nClose and start again?", "OHNOES", 4)
if ($answer -eq "YES") {
Stop-Process -name $processName
}
Else {
exit
}
}

# Do we recognize the current network?
if ($synergyWorkSubnets -contains $location) {
BalloonTip "IP: $($currentIPaddress)`nServer: $($synergyServerWork)`nConnecting to Synergy server at work."
& $synergyClientProgram $synergyServerWork
exit
}
ElseIf ($synergyHomeSubnets -contains $location) {
BalloonTip "IP: $($currentIPaddress)`nServer: $($synergyServerHome)`nConnecting to Synergy server at home."
& $synergyClientProgram $synergyServerHome
exit
}
Else {
$answer = [System.Windows.Forms.MessageBox]::Show("Network not recognized by IP address: {0}`n`nLaunch Synergy?" -f $unrecognized, "OHNOES", 4)
if ($answer -eq "YES") {
& $synergyLauncherProgram
}
}

Then I saved the script in "C:\Program Files\SynergyStart\", created a shortcut and used the Change Icon button to make the same as Synergy’s and made the Target:
C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -WindowStyle Hidden & 'C:\Program Files\SynergyStart\synergy.ps1'

Lastly, I copied the shortcut into the directory of things that run when the system starts up:
%APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup

Now, Synergy connects to the needed server at home and work. If it can’t figure out where it is, it asks if it should run it at all.

As they say, a millisecond saved is a millisecond earned.

This post was very nearly published without a Linux equivalent. Nearly.

Same trick for bash/zsh: #!/bin/zsh

# Define Synergy server IP addresses
synergyServerWork="192.168.111.11"
synergyServerHome="192.168.222.22"

# Define partial IP addresses that will indicate which server to use
synergyWorkSubnets=("192.168.111" "192.168.115")
synergyHomeSubnets=("192.168.222" "192.168.225")

# Path to Synergy Client (synergyc)
synergyClientProgram="/usr/bin/synergyc"

# Path to QuickSyngery, for when we cannot identify the network
synergyLauncherProgram="/usr/bin/quicksynergy"

# Remove path and file extension to give us the process name
processName=`basename $synergyClientProgram`

# Grab current IP address, assumes '192' is in use. (e.g., 192.168.1.1)
currentIPaddress=`ip addr show | grep 192 | awk "{print $2}" | sed 's/inet //;s/\/.*//;s/ //g'`

# Find the subnet of current IP address
location=`echo $currentIPaddress | cut -d '.' -f 1,2,3`

for i in "${synergyWorkSubnets[@]}"
do
if [ "${i}" = "${location}" ]
then
break
fi
done

#main

# If Synergy client is already running, do we need to restart it?
running=`ps ax | grep -v grep | grep $processName`
if [ $running ]
then
if `zenity --question --ok-label="Yes" --cancel-label="No" --text="Synergy is running.\nClose and start again?"`
then
pkill $processName
else
exit
fi
fi

# Do we recognize the current network?
for i in "${synergyWorkSubnets[@]}"
do
if [ "${i}" = "${location}" ]
then
notify-send "IP:$currentIPaddress Server:$synergyServerWork [WORK]"
$synergyClientProgram $synergyServerWork
exit
fi
done

for i in "${synergyHomeSubnets[@]}"
do
if [ "${i}" = "${location}" ]
then
notify-send "IP:$currentIPaddress Server:$synergyServerWork [HOME]"
$synergyClientProgram $synergyServerHome
exit
fi
done

if `zenity --question --ok-label="Yes" --cancel-label="No" --text="Network not recognized by IP address: $currentIPaddress\nLaunch Synergy?"`
then
$synergyLauncherProgram
fi

To get it to run automatically, you might choose to call the script from /etc/init.d/rc.local.

Download here:
  PowerShell:
    synergy.ps1
  GNU/Linux:
    synergy.sh


Tags: , ,
Permalink: 20140125.network_aware_synergy_client

Thu, 06 Jun 2013

Managing to use man pages through simple CLI tips

Recently, an author I admire and time-honored spinner of the Interwebs, Tony Lawrence emphasized the value of using man pagesmanual pagesDocumentation available from the command line.
> man ls
as a sanity check before getting carried away with powerful commands. I didn’t know about this one but he has written about a situation in which killall could produce some shocking, and potentially quite unpleasant, results.

Personally, I often quickly check man pages to be certain that I am using the correct flags or, as in the above case, anticipating results that bear some resemblance to what is actually likely to happen. Yet, it seems many people flock toward SERPSearch Engine Results Page A tasteful replacement for mentioning any particular search-engine by name.
Also useful as a verb:
I dunno. You’ll have to SERP it.
s for this information.

Perhaps the most compelling reason to head for the web is leaving the cursor amid the line you’re working on, without disturbing the command. SERPing the command however, could easily lead you to information about a variant that is more common than the one available to you. More importantly, the information retrieved from the search engine is almost certainly written by someone who did read the man page — and may even come with the admonishment that you RTFMRead The F#!$!*#’n Manual as a testament to the importance of developing this habit.

This can be made easier with just a few CLI shortcuts.

<CTRL+u> to cut what you have typed so far and <CTRL+y> to paste it back.

That is, you press <CTRL+u> and the line will be cleared, so you can then type man {command} and read the documentation. Don’t hesitate to jot quick notes of which flags you intend to use, if needed. Then exit the man page, press <CTRL+y> and finish typing right where you left off.

This is another good use for screen or tmux but let’s face it. There are times when you don’t want the overhead of opening another window for a quick look-up and even instances when these tools aren’t available.

A few other tips to make life easier when building complex commands:

Use the command fc to open up an editor in which you can build your complex command and, optionally, even save it as a shell script for future reuse.

Repeat the last word from the previous command (often a filename) with <ALT+.> or use an item from the last command by position, in reverse order:
> ls -lahtr *archive*
<ALT+1+.> : *archive*
<ALT+2+.> : -lahtr
<ALT+3+.> : ls

You can also use Word Designators to use items from history, such as adding sudo to the last command typed by:
sudo !!

This allows for tricks like replacing bits of a previous command:
!:s/misspelled/corrected/

Lastly, if you need a command that was typed earlier, you can search history by pressing <CTRL+r> and start typing an identifying portion of the command.

(Note: I have used these in Zsh and Bash, specifically. They can, however, be missing or overwritten — if a feature you want isn’t working, you can bind keys in a configuration file. Don’t just write it off, once you’ve solved the problem it will never again be an intimidating one.)

Happy hacking!


Tags: , , , , , , , ,
Permalink: 20130606.managing.to.use.man.pages

Mon, 13 May 2013

Zsh and hash

Documentation for this one seems a bit hard to come by but it is one of the things I love about Zsh.

I’ve seen many .bashrc files that have things like:
alias www='cd /var/www'
alias music='cd /home/j0rg3/music'

And that’s a perfectly sensible way to make life a little easier, especially if the paths are very long.

In Zsh, however, we can use the hash command and the shortcut we get from it works fully as the path. Other words, using the version above, if we want to edit ‘index.html’ in the ‘www’ directory, we would have to issue the shortcut to get there and then edit the file, in two steps:
> www
> vim index.html

The improved version in .zshrc would look like:
hash www=/var/www
hash -d www=/var/www

Then, at any time, you can use tilde (~) and your shortcut in place of path.
> vim ~www/index.html

Even better, it integrates with Zsh’s robust completions so you can, for example, type cd ~www/ and then use the tab key to cycle through subdirectories and files.

On this system, I’m using something like this:
(.zshrc)
hash posts=/home/j0rg3/weblog/posts
hash -d posts=/home/j0rg3/weblog/posts

Then we can make a function to create a new post, to paste into .zshrc. Since we want to be able to edit and save, without partial posts becoming visible, while we are working, we’ll use an extra .tmp extension at the end:
post() { vim ~posts/`date +%Y-%m`/`date +%Y%m%d`.$1.txt.tmp }

[ In-line date command unfamiliar? See earlier explanation ]

But, surely there is going to be a point when we need to save a post and finish it later. For now, let’s assume that only a single post will be in limbo at any time. We definitely don’t want to have to remember the exact name of the post — and we don’t want to have hunt it down every time.

We can make those things easier like this:
alias resume="vim `find ~posts/ -name '*.txt.tmp'`"

Now, we can just enter resume and the system will go find the post we were working on and open it up for us to finish. The file will need the extension renamed from .txt.tmp to only .txt to publish the post but, for the sake of brevity, we’ll think about that (and having multiple posts in editing) on another day.


Tags: , , , ,
Permalink: 20130513.zsh.and.hash

Tue, 07 May 2013

Welcome, traveler.

Thanks for visiting my little spot on the web. This is a Blosxom ‘blog which, for those who don’t know, is a CGI written in Perl using the file-system (rather than a database).

To the CLI-addicted, this is an awesome little product. Accepting, of course, that you’re going to get under the hood if you’re going to make it the product you want. After some modules and hacking, I’m pleased with the result.

My posts are just text files, meaning I start a new one like: vim ~posts/`date +%Y%m%d`.brief.subject.txt

Note: the back-ticks (`) tell the system that you want to execute the command between ticks, and dynamically insert its output into the command. In this case, the command date with these parameters:
  1. (+) we’re going to specify a format
  2. (%Y) four-digit year
  3. (%m) two-digit month
  4. (%d) two-digit day
That means the command above will use Vim to edit a text file named ‘20130507.brief.subject.txt’ in the directory I have assigned to the hash of ‘posts’. (using hash this way is a function of Zsh that I’ll cover in another post)

In my CLI-oriented ‘blog, I can sprinkle in my own HTML or use common notation like wrapping a word in underscores to have it underlined, forward-slashes for italics and asterisks for bold.

Toss in a line that identifies tags and, since Perl is the beast of Regex, we pick up the tags and make them links, meta-tags, etc.

Things here are likely to change a lot at first, while I twiddle with CSS and hack away at making a Blosxom that perfectly fits my tastes — so don’t be too alarmed if you visit and things look a tad wonky. It just means that I’m tinkering.

Once the saw-horses have been tucked away, I’m going to take the various notes I’ve made during my years in IT and write them out, in a very simple breakdown, aimed at sharing these with people who know little about how to negotiate the command line. The assumption here is that you have an interest in *nix/BSD. If you’ve that and the CLI is not a major part of your computing experience, it probably will be at some point. If you’re working on systems remotely, graphical interfaces often just impede you.

Once you’ve started working on remote machines, the rest is inevitable. You can either remember how to do everything two ways, through a graphical interface and CLI — or just start using the CLI for everything.

So let’s take a little journey through the kinds of things that make me love the CLI.


Tags: , , , , , , , , ,
Permalink: 20130507.greetings