Tutorial by Examples: r

Usually, you have to use git add or git rm to add changes to the index before you can git commit them. Pass the -a or --all option to automatically add every change (to tracked files) to the index, including removals: git commit -a If you would like to also add a commit message you would do: g...

Perl tries to do what you mean: print "Hello World\n"; The two tricky bits are the semicolon at the end of the line and the \n, which adds a newline (line feed). If you have a relatively new version of perl, you can use say instead of print to have the carriage return added automatical...

An unordered list can be created with the <ul> tag and each list item can be created with the <li> tag as shown by the example below: <ul> <li>Item</li> <li>Another Item</li> <li>Yet Another Item</li> </ul> This will produce a...

An ordered list can be created with the <ol> tag and each list item can be created with the <li> tag as in the example below: <ol> <li>Item</li> <li>Another Item</li> <li>Yet Another Item</li> </ol> This will produce a numbere...

One common pitfall when using dictionaries is to access a non-existent key. This typically results in a KeyError exception mydict = {} mydict['not there'] Traceback (most recent call last): File "<stdin>", line 1, in <module> KeyError: 'not there' One way to avoid...

Right after you install Git, the first thing you should do is set your username and email address. From a shell, type: git config --global user.name "Mr. Bean" git config --global user.email [email protected] git config is the command to get or set options --global means that the ...

To see the log in a prettier graph-like structure use: git log --decorate --oneline --graph sample output : * e0c1cea (HEAD -> maint, tag: v2.9.3, origin/maint) Git 2.9.3 * 9b601ea Merge branch 'jk/difftool-in-subdir' into maint |\ | * 32b8c58 difftool: use Git::* functions instead of...

$ tail -f /var/log/syslog > log.txt [1]+ Stopped tail -f /var/log/syslog > log.txt $ sleep 10 & $ jobs [1]+ Stopped tail -f /var/log/syslog > log.txt [2]- Running sleep 10 &

The function rand() can be used to generate a pseudo-random integer value between 0 and RAND_MAX (0 and RAND_MAX included). srand(int) is used to seed the pseudo-random number generator. Each time rand() is seeded wih the same seed, it must produce the same sequence of values. It should only be see...

Here's a standalone random number generator that doesn't rely on rand() or similar library functions. Why would you want such a thing? Maybe you don't trust your platform's builtin random number generator, or maybe you want a reproducible source of randomness independent of any particular library ...

> redirect the standard output (aka STDOUT) of the current command into a file or another descriptor. These examples write the output of the ls command into the file file.txt ls >file.txt > file.txt ls The target file is created if it doesn't exists, otherwise this file is truncated. ...

< reads from its right argument and writes to its left argument. To write a file into STDIN we should read /tmp/a_file and write into STDIN i.e 0</tmp/a_file Note: Internal file descriptor defaults to 0 (STDIN) for < $ echo "b" > /tmp/list.txt $ echo "a" >> ...

File descriptors like 0 and 1 are pointers. We change what file descriptors point to with redirection. >/dev/null means 1 points to /dev/null. First we point 1 (STDOUT) to /dev/null then point 2 (STDERR) to whatever 1 points to. # STDERR is redirect to STDOUT: redirected to /dev/null, # effect...

2 is STDERR. $ echo_to_stderr 2>/dev/null # echos nothing Definitions: echo_to_stderr is a command that writes "stderr" to STDERR echo_to_stderr () { echo stderr >&2 } $ echo_to_stderr stderr

Truncate > Create specified file if it does not exist. Truncate (remove file's content) Write to file $ echo "first line" > /tmp/lines $ echo "second line" > /tmp/lines $ cat /tmp/lines second line Append >> Create specified file if it does not e...

The type of the literal Without any extensions, the type of a string literal – i.e., something between double quotes – is just a string, aka list of characters: Prelude> :t "foo" "foo" :: [Char] However, when the OverloadedStrings extension is enabled, string literals be...

Defines an <initially-hidden> custom element which hides its contents until a specified number of seconds have elapsed. const InitiallyHiddenElement = document.registerElement('initially-hidden', class extends HTMLElement { createdCallback() { this.revealTimeoutId = null; } at...

6 Exceptions are to synchronous code what rejections are to promise-based asynchronous code. If an exception is thrown in a promise handler, its error will be automatically caught and used to reject the promise instead. Promise.resolve(5) .then(result => { throw new Error("I ...

Runtime errors in JavaScript are instances of the Error object. The Error object can also be used as-is, or as the base for user-defined exceptions. It's possible to throw any type of value - for example, strings - but you're strongly encouraged to use Error or one of it's derivatives to ensure that...

Browse to File > New > Solution to bring you up the new project dialog Select Single View App and press Next Configure your app by setting your app name and organization ID, and press Next: Set your Project name and Solution name, or leave as the default name. Click Create to create...