Capturing Screen shots on Android via ADB

Let's use screencap tool on Android to capture a screen shot and save it to a file on Android's internal /sdcard.

adb shell screencap -p /sdcard/myScreenShot.png

Ok, lets capture a series of screen shots - a movie.

adb shell mkdir -p /sdcard/moovie1; 

for i in `seq -w 1 1 155`; do \

  adb shell screencap -p /sdcard/moovie1/cap_$i.png && \

  echo -e "cap_$i.png"; \

done;

Now let's download the images:

for i in `seq -w 1 1 155`; do \

  adb pull /sdcard/moovie1/cap_$i.png && \

  adb shell rm /sdcard/moovie1/cap_$i.png && \

  echo -e "cap_$i.png\n"; \

done;

Ok, now let's make a movie with help of well-known imagemagick tool::
Scale images to 50% size and convert them to GIF format.

for i in `ls`; \
  do convert $i -scale 50% $i.gif; \
done;

convert -delay 100 -loop 0 cap*.gif animated_screen.gif

Also one could use following script to save captured images directly to computer

 adb shell screencap -p | sed 's/\r$//' > screen.png 

or 

adb shell screencap -p | perl -pe 's/\x0D\x0A/\x0A/g' > screen.png

to cat images directly to a file on a computer (src)

(but for series of screen shots that will be a bit slower).

adb shell screencap -h

usage: screencap [-hp] [-d display-id] [FILENAME]

   -h: this message

   -p: save the file as a png.

   -d: specify the display id to capture, default 0.

If FILENAME ends with .png it will be saved as a png.

If FILENAME is not given, the results will be printed to stdout.

A strange way to populate SSH keys from Jenkins to Jenkins Slave node

Using sshpass tool as a workaround for ssh interactive password prompt. :-)

mkdir tmpz

cd tmpz

wget --output-document=sshpass.tgz "http://downloads.sourceforge.net/project/sshpass/sshpass/1.05/sshpass-1.05.tar.gz?r=http%3A%2F%2Fsourceforge.net%2Fprojects%2Fsshpass%2Ffiles%2Fsshpass%2F&ts=1380045506&use_mirror=freefr"

tar -zxvf sshpass.tgz

cd sshpass-1.05

./configure

make

./sshpass -p "hudson"  ssh-copy-id -i ~/.ssh/id_rsa.pub hudson@10.116.65.165

Use perl to edit multiple lines XML

Ok, here is a strange request - to edit some xml file over ssh on Mac OS X.

One needs to change false to true in following

<key>system.privilege.taskport</key> <dict> <key>allow-root</key> <false/>

Luckily, Mac OS X has perl (not sure if it was installed along with XCode). So let's use perl for that:

ssh user@192.168.1.2 "set -x; \
echo 'Password' | sudo -S \
perl -p -0777 -i -e 's@<key>system.privilege.taskport</key>.*?<dict>.*?<key>allow-root</key>.*?<false/>@<key>system.privilege.taskport</key>\n\t\t<dict>\n\t\t\t<key>allow-root</key>\n\t\t\t<true/>@sg' /etc/authorization"

Breaking this down:

• -p tells it to loop through the input and print
• -0777 tells it to use the end of file as the input separator, so that it gets the whole thing in in one slurp
• -e means here comes the stuff I want you to do

And the substitution itself:

• use @ as a delimiter so you don't have to escape /
• use *?, the non-greedy version, to match as little as possible, so we don't go all the way to the last occurrence of </xyz> in the file
• use the s modifier to let . match newlines (to get the multiple-line tag values)
• use the g modifier to match the pattern multiple times

Perl expression was constructed with help of this answer from stackoverflow.

Insert a text at pattern using regexp in VIM

Say one is editing a text file in vim:

blah-blah234qqqqqqqqqq

blah-blah345234qqqqqqqqqq

and would like to insert a space at position after blah-blah345[digits] in each line.

One could use a following search-n-replace expression with help of regexp:

:%s/\(blah-blah\d\+\)/\1  /g

\( \) - for group selection

\1 - for first group selected

\d - for digit

http://vimregex.com/

Find elements by XPath with JavaScript (example)

Get elements from action menu on mail page of yandex.ru:

r = document.evaluate("//*[@class='b-toolbar__block b-toolbar__block_chevron']/a", document, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);

el = r.iterateNext();

while(el) { 
  if (window.getComputedStyle(el).display == "none") {
    continue; 
  } 
  console.log(el.getAttribute('data-action')); 
  el=r.iterateNext();
}

http://www.w3.org/TR/DOM-Level-3-XPath/xpath.html#XPathResult

https://developer.mozilla.org/en-US/docs/Web/API/document.evaluate?redirectlocale=en-US&redirectslug=DOM%2Fdocument.evaluate

Using tar pipe for copying directory excluding files or directories.

A nice use case for tar pipe

Say we have a directory, with tons of subdirectories, each of which is a checked subversion project.

Dir structure looks like this.

RootDir / 

  /dir1/

    .svn

    dirs....

  /dir2/

    .svn

    dirs....

One wants to copy everything but .svn dirs.

Let's use tar pipe for that: 

tar --exclude \.svn -c RootDir | tar -C /path/to/destination/ -xv

Reveal Developer options on OS Android >= 4.2

On devices with OS Android >= 4.2  menu item "Developer options" appears to be hidden.

If you ever want to enable "Developer options" on your device, please do the following:

1. Go to Settings -> About tablet 

2. Perform about 7 taps on item Build number (the last menu item on the list)

Then "{} Developer options" will appear.

Jenkins + Gradle + Proxy

To make Gradle use HTTP Proxy when executing on Jenkins with Gradle plugin installed,

one has to use Environment variable JAVA_OPTS to pass proxy servers to Gradle.

For example:

JAVA_OPTS=-Dhttps.proxyHost=192.168.1.1 -Dhttps.proxyPort=3128 -Dhttp.proxyHost=192.168.1.1 -Dhttp.proxyPort=3128

Also one could use gradle.properties or configure gradle build files to use proxies.

Though JAVA_OPTS is a more universal way as one could have multy node configuration of Jenkins. For example: master does not use proxy, and some slave node is located behind proxy, so setting JAVA_OPTS in node environment will do the job.