Ubuntu 12.04 - create a simple daemon (service) for your application

Creating a daemon in Linux is as simple as creating a BASH/SH script in /etc/init.d. BASH is NOT part of this short tutorial so I won't go into the details of the script itself.

To create a daemon create a script in /etc/init.d. To simplify the creation you can copy the skeleton script in /etc/init.d/skeleton. Your script need to handle the following daemon commands:
start
stop
restart/reload
force-reload
status

cp /etc/init.d/skeleton /etc/init.d/daemonName
sudo chmod 775 /etc/init.d/daemonName

To enable the daemon to start at boot:
update-rc.d daemonName defaults 97 03

http://manpages.ubuntu.com/manpages/hardy/man8/update-rc.d.8.html


To disable the daemon from starting at boot:

update-rc.d -f daemonName remove

Git - tips for console users

Get the tree-like view of commits in terminal

git log --graph --oneline --all

Get current branch name

git branch

Pull and rebase local changes

git pull --rebase



Revert all local changes in a GIT managed project

git reset --hard HEAD

or

git checkout .
git reset
git revert ...

and

git clean -df & git checkout -- .
(and press enter)



Check whether there are any uncommited branches

git log --branches --not --remotes

Extract three topmost commits from the current branch 

git format-patch -3


Check if there are any conflicts before applying the patch

git apply --check patch_name.patch

Apply a patch file to the local work-space

git apply patch_name.patch

Archlinux setting up VPN - couldn't open the /dev/ppp device: No such device or address

While configuring VPN on archlinux I followed the guide on:
https://wiki.archlinux.org/index.php/PPTP_VPN_client_setup_with_pptpclient


archlinux couldn't open the /dev/ppp device: No such device or address


SOLUTION:
add a new file:

nano /etc/modprobe.d/modules.conf

with the line:

alias char-major-108 ppp_generic

Linux - simple rar archive operations - checksum and rar archive test

1. Check checksums of files listed in ’files.sfv’: 

cksfv -f files.sfv 

2. Create checksums for a bunch of files: 

cksfv *.rar > files.sfv

3. Test rar achive
unrar t archive_name.rar

Spring REST - access HTTP header data on the server side

This is an example of a simple REST call on the server side;

The call looks like the following:

[GET] http://localhost:8080/rest/user/getUser/userNameABC
Accept: application/json
Authorization: 123456


@RequestMapping(value="/getUser/{login}", method = RequestMethod.GET, produces="application/json", headers="Accept=application/json")
@ResponseBody
public User getUser(
   @RequestHeader(value = "Authorization", required = true) String authorization,
   @PathVariable String login) {
   
     if (login.isEmpty())
        return null;

     [....]
}

The @RequestHeader accesses for us data in the header. We can also get the Accept parameter by adding:

@RequestHeader(value = "Accept") String acceptString

Android - Find main activity name of the running application

Run as Android superuser:
adb shell dumpsys activity

This gives you the dump of all running activities. I wanted to find the activity name of the sftp server that was running in the background.

The line of interest was:

Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10104000 pkg=com.icecoldapps.httpsftpsserver cmp=com.icecoldapps.httpsftpsserver/.viewStart bnds=[145,610][345,787] }
      Hist #2: ActivityRecord{42d5cb18 com.icecoldapps.httpsftpsserver/.viewStart}
        Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10104000 pkg=com.icecoldapps.httpsftpsserver cmp=com.icecoldapps.httpsftpsserver/.viewStart bnds=[145,610][345,787] }
        ProcessRecord{42c29950 15592:com.icecoldapps.httpsftpsserver/u0a6} 

So the main activity name is:
.viewStart


I was able to remotely start the application by firing up the command:
adb shell su -c "am start -n "com.icecoldapps.httpsftpsserver/.viewStart""
( I needed superuser priviledges)

To start this Android application as a regular user enter:
adb shell am start -n "com.icecoldapps.httpsftpsserver/.viewStart"

To kill the application:
adb shell am force-stop com.icecoldapps.httpsftpsserver

To uninstall the application:
adb shell pm uninstall com.icecoldapps.httpsftpsserver

IntelliJ Android application - Android SDK is not specified

Are you getting a compile error:
Android Source Generator: [] Android SDK is not specified
?

These screens show how to properly configure IntelliJ to compile an Android application.