This will create a new git repo in the folder named learngit.
We are ready now to use git within our local system.
When we say git init , it creates a directory named .git inside the folder.
This contains the stuff needed by git to work.
If you want to copy existing code base in git to your local system , you have another way.
git clone url_name
Create a new file named readme.txt
Add some content to it
git add readme.txt
This command it telling that i want this file to be considered for saving it git.
When we say this , git stores that to index.
Commit the file
git commit --message "Adding a new file"
This command saves the file which we added to index into the git.
Git log shows the history about what work has been done and by whom
We can use this command to find difference the two commits
git diff master~1 master
Another similar syntax is
This will show changes to all the files onto master on current version from previous commit
git diff master~1 master --filename.txt
If you want to see diff only for specific file you can use above command.
without an argument views the differences between the current
working directory and the index staging area.
git diff master
views the differences between the current working directory and the last commit on the
default master branch
While working with word documents you might want to use the
This shows diff at the word level rather then lines
git diff --word-diff master~1 master --filename.txt
Another format of diff is
This command shows the summary in terms of line changes + and - , rather than details about changes.
To see what is the sha for given reference (branch or master)
use the following example
git rev-parse master
Maven has set of lifecycles
Goals ( Tasks in Ant)
Maven has following lifecycles
default ( build and deployment )
clean ( used to clean )
site ( used for documentation )
Each phase can have number of goals
Phases are executed in sequence
All previous phases ( and goals ) are executed if you call some phase
You can assign goals to phases via plugins goals
e.g Maven syntax
SBT is better for
Ease of making new tasks
Test and development features for incremental builds
Sbt just has tasks
Tasks can have dependency with each other.
Tasks with no dependency are executed in parallel
Tasks output can be passed on to next output
Settings are values ( e.g ) Project name
If something is reusable tasks which is done again and again in different projects , we can abstract it as plugin.
This plugin can be used in different projects and can be sourced by build file of projects.
Download and add sbt to your path
Every project using sbt should have two files:
build.properties tell which version of sbt to use
build.sbt tells which all settings are applicable for this project , including the library dependencies
start sbt by typing sbt at command prompt
After sbt starts , you can see the help by typing
This will show all of the help topics
help Displays this help message or prints detailed help on requested commands (run 'help <command>').
about Displays basic information about sbt and the build.
tasks Lists the tasks defined for the current project.
settings Lists the settings defined for the current project.
reload (Re)loads the project in the current directory
projects Lists the names of available projects or temporarily adds/removes extra builds to the session.
project Displays the current project or changes to the provided `project`.
set [every] <setting> Evaluates a Setting and applies it to the current project.
session Manipulates session settings. For details, run 'help session'.
inspect [uses|tree|definitions] <key> Prints the value for 'key', the defining scope, delegates, related definitions, and dependencies.
<log-level> Sets the logging level to 'log-level'. Valid levels: debug, info, warn, error
; <command> (; <command>)* Runs the provided semicolon-separated commands.
~ <command> Executes the specified command whenever source files change.
last Displays output from a previous command or the output from a specific task.
last-grep Shows lines from the last output for 'key' that match 'pattern'.
export <tasks>+ Executes tasks and displays the equivalent command lines.
exit Terminates the build.
--<command> Schedules a command to run before other commands on startup.
show <key> Displays the result of evaluating the setting or task associated with 'key'.
This will show which all tasks are defined for this project
This will show which all settings are applicable for this project
For example which is sScalaversion etc
This is a list of settings defined for the current project.
It does not list the scopes the settings are defined in; use the 'inspect' command for that.
autoCompilerPlugins If true, enables automatically generating -Xplugin arguments to the compiler based on the classpath for the plugin configuration.
autoScalaLibrary Adds a dependency on scala-library if true.
baseDirectory The base directory. Depending on the scope, this is the base directory for the build, project, configuration, or task.
classDirectory Directory for compiled classes and copied resources.
crossPaths If true, enables cross paths, which distinguish output directories for cross-building.
fork If true, forks a new JVM when running. If false, runs in the same JVM as the build.
initialCommands Initial commands to execute when starting up the Scala interpreter.
javaHome Selects the Java installation used for compiling and forking. If None, uses the Java installation running the build.
javaSource Default Java source directory.
libraryDependencies Declares managed dependencies.
managedResourceDirectories List of managed resource directories.
maxErrors The maximum number of errors, such as compile errors, to list.
name Project name.
offline Configures sbt to work without a network connection where possible.
organization Organization/group ID.
publishArtifact Enables (true) or disables (false) publishing an artifact.
publishTo The resolver to publish to.
resourceDirectory Default unmanaged resource directory, used for user-defined resources.
scalaHome If Some, defines the local Scala installation to use for compilation, running, and testing.
scalaSource Default Scala source directory.
scalaVersion The version of Scala used for building.
sourceDirectories List of all source directories, both managed and unmanaged.
sourceDirectory Default directory containing sources.
target Main directory for files generated by the build.
unmanagedBase The default directory for manually managed libraries.
unmanagedResourceDirectories Unmanaged resource directories, containing resources manually created by the user.
unmanagedSourceDirectories Unmanaged source directories, which contain manually created sources.
version The version/revision of the current module.
More settings may be viewed by increasing verbosity. See 'help settings'.
> settings name
More settings may be searched by increasing verbosity. See 'help settings'.
> settings scalaVersion
The version of Scala used for building.
More settings may be searched by increasing verbosity. See 'help settings'.
This will show set of possible options with tasks similar to test
To run only particular test in sbt
> testOnly <TESTNAME>
When sbt reads your project description,
it reads the .sbt files in the root directory,
the .sbt files in /project and
.scala files in /project.
It compiles everything that it finds and this gives you your build definition. sbt then runs this build and creates your artifact, your jar or whatever.
Difference between dependency and plugin
A plugin is simply a jar which contains settings or tasks. The jar contains a definition
file which sbt reads to work out what settings and tasks are available.
At my work i login to server via an intermediary server.
So to go to machine i have to first
Laptop > Inter > WorkMachine
Lets abbrevate the as
L > I > W
So to directly login via ssh from my L to W i setup multi hop ssh
First we need to generate some key on L
Now login to machine Inter (I)
Add the details of newly created ssh key
Save it and exit
Just try to ssh from Laptop to Inter
This should allow you to directly ssh from laptop to inter without password.
Now login to WorkMachine and add the key to its authorized keys also following above steps
In your laptop local ssh config add the following
Paste the content below
ProxyCommand ssh -q inter nc %h 22
To login from laptop directly to WorkMachine