Initial

cheat-sheet.md

+# GIT
+## Password issues
+To avoid entering username and password everytime you pull/push to a git repository, there are two known ways.
+* Add your SSH public key to the remote end (this is possible with either github, gitlab or a private remote server)
+* Setup your `~/.gitconfig` like:
+  ```
+  # This is Git's per-user configuration file.
+  [user]
+        name = vihari
+        email = viharipiratla@gmail.com
+  [credential]
+        helper = osxkeychain
+  ```
+  The `osxkeychain` works only on Mac and I use `/usr/share/doc/git/contrib/credential/gnome-keyring/git-credential-gnome-keyring` on Linux.
+  For more: [refer](http://blog.iqandreas.com/git/storing-https-authentication-in-ubuntu-and-arch-linux/)
+
+## Pulling and Pushing
+Every git repository contains a folder called `.git` and `config` file in it which defines the url of the remote bare repository.
+One can configure the file to add any other remote servers not listed on modify the existing one. 
+
+Assuming that you have the repository configured, you can use `git pull origin master` for pulling any changes on master branch of origin repo. 
+Similarly, `git push origin master` to push any changes on the local machine to remote server
+
+## Branch creation and merging
+Branches can fork the development and lets one work on a feature for a short duration without worrying about breaking the system.
+### Creation
+
+```
+# list all the branches in this repo.
+# the current branch is prefixed with '*' and is colored green
+git branch
+# create a branch
+git branch <branch name>
+# switch to a branch
+git checkout <branch name>
+# push the changes in a branch
+git push origin <branch name>
+```
+
+### Merging
+The following commands will merge the changes of master into a branch called `feature`.
+
+`git chekout feature; git merge master`  
+or  
+`git merge master feature`
+
+There are certain problems using git merge, whenever a branch is merged the log history is no more linear and makes it hard to understand it through git log.
+
+Another way of merging two branches is through `git-rebase`. 
+**The golden rule of git rebase is to never use it on public branches.**
+
+`git checkout feature; git rebase master`  
+
+Use the command above to also merge the changes but for a linear commit history. 
+The changes will look as though feature is developed on the tip of master;
+Refer [Tutorial](https://www.atlassian.com/git/tutorials/merging-vs-rebasing/summary)
+
+## Revert/Reset
+If you want to revert a commit or just want to reset the code base, the use: `git reset --hard <commit-id>`.
+`commit-id` is the commit id of the commit that you want to reset to.
+This command should be used with caution, since it nullifies all the changes in the working directory.
+
+Use `--soft` instead of `--hard` is you want to keep the changes to the files, but want to remove some commits in the history.
+
+## Misc
+`git log` shows the log messages and `git log -p` displays the files changed and the changes with each commit.
+
+## View the files changed
+
+`git diff --name-only --diff-filter=U`  
+will list all the modified files, if you wish to also see the change summary along with the files then use
+`git diff --diff-filter=U`  
+http://stackoverflow.com/questions/3065650/whats-the-simplest-way-to-git-a-list-of-conflicted-files
+
+`git diff --cached`  
+To view all the changes staged for commit.
+
+## Submodules (Advanced)
+Through submodules, we can add dependency from the current project to any other git project.
+
+`git submodule sync`  
+When the path to a gitmodue is changed in `.gitmodule` then use this command for the changes to be reflected in the .git/conf file.  
+`git submodule update --recursive --remote`  
+Updates the submodules -- http://stackoverflow.com/questions/1030169/easy-way-pull-latest-of-all-submodules
+
+# Emacs [Domesticating the wild beast] 
+
+**Moving to the next line: ** `ALT+[f/b]` http://stackoverflow.com/questions/2078855/about-the-forward-and-backward-a-word-behaviour-in-emacs
+**Moving to a column: ** `ALT+x` and `move-to-colum #column` which is bound to `M-g TAB`.
+
+## Org Mode [The feature that makes Emacs irresistable]
+You can make presentations, tables, ToDo lists and export them to html, pdf, jkyll etc. with this.
+
+# PERL [You never cease to amaze me]
+
+# MISC [Linux Man! Linux]
+
+`sort|uniq` is equivalent to `sort -u`
+
+use cut(1) as `cut -d $D -f @F` instead of `perl -ane '@fs=split('$D');map {print $fs[$_]} @F'`
+
+`[command] -- ` -- `rm -- -*`  
+If you want to pass a parameter with - in it and not allow it to be treated as command line argument then just put -- at the arg list and any subsequent words will be treated as params.
+In the example above, to remove all files in the dir that start with '-' use it like shown.
+
+Set the command line history off with `set +o history` and on with: `set -o history`.  
+Alternatively, if you want to completely disable history then: `unset HISTFILE`.
+
+## cURL
+
+Send form data using cURL with `curl -d 'param1=value1' -d 'param2=value2' URL`.  
+A handy command: `curl -d "uname=P16495" -d "passwd=<pwd>" https://internet.iitb.ac.in/index.php` to login into internet at IITB. [do not bother about special chars like '@' in the password]
+
+Use `-L` to handle redirects.
+
+# JAVA
+
+To write UTF-8 content into files use:  
+`
+Writer out = new BufferedWriter(new OutputStreamWriter(
+    new FileOutputStream("outfilename"), "UTF-8"));
+try {
+    out.write(aString);
+} finally {
+    out.close();
+}
+`  
+