on 22-May-2018 (Tue)

YAML (YAML Ain't Markup Language) is a human-readable data serialization language.

iterable

An object capable of returning its members one at a time. Examples of iterables include all sequence types (such as list , str , and tuple ) and some non-sequence types like dict , file objects , and objects of any classes you define with an __iter__() method or with a __getitem__() method that implements Sequence semantics.

Iterables can be used in a for loop and in many other places where a sequence is needed ( zip() , map() , …). When an iterable object is passed as an argument to the built-in function iter() , it returns an iterator for the object. This iterator is good for one pass over the set of values. When using iterables, it is usually not necessary to call iter() or deal with iterator objects yourself. The for statement does that automatically for you, creating a temporary unnamed variable to hold the iterator for the duration of the loop. See also iterator , sequence , and generator .

Iterables can be used in a for loop and in many other places where a sequence is needed ( zip() , map() , …).

When an iterable object is passed as an argument to the built-in function iter() , it returns an iterator for the object.

This should mean great things for Australia, a country so rich in solar potential that some have dubbed it the Saudi Arabia of solar.

Scientists have argued that oxybenzone and octinoxate accelerate coral bleaching and prevent reefs from regenerating, making them less resilient to climate change. According to the bill, HI SB2571, scientific studies show that the chemicals also threaten fish populations.

In southeastern Venezuela, huge sandstone towers tower thousands of feet above the forest. The tepuis, as they are known, are the remnants of an enormous plateau. The flat formations are covered with bizarre rock formations. The primeval landscape served as inspiration for Sir Arthur Conan Doyle’s dinosaur-infested “The Lost World

Many species on the tepui summits are found nowhere else. How did those species get there?

when creating directory, mkdir -p mydir Create intermediate directories as required.

• Make allows us to specify what depends on what and how to update things that are out of date.

Use # for comments in Makefiles.

Write rules as target: dependencies.

Specify update actions in a tab-indented block under the rule.

• Use .PHONY to mark targets that don’t correspond to files.

Use $@ to refer to the target of the current rule.

Target names should use hyphened lowercase.

Variables not special to make or the environment should be in underscored lowercase.

Use $^ to refer to the dependencies of the current rule.

• Use $< to refer to the first dependency of the current rule.

Include scripts in dependency list to make results depend on processing scripts as well as data files.

• Dependencies are transitive: if A depends on B and B depends on C, a change to C will indirectly trigger an update to A.

Use the wildcard % as a placeholder in targets and dependencies.

• Use the special variable $* to refer to matching sets of files in actions.

Define variables by assigning values to names.

• Reference variables using $(...).

Make is actually a small programming language with many built-in functions.

Use wildcard function to get lists of files matching a pattern.

• Use patsubst function to rewrite file names.

• Document Makefiles by adding specially-formatted comments and a target to extract and format them.

Makefiles save time by automating repetitive work, and save thinking by documenting how to reproduce results.

To use a Makefile with a different name, use the -f flag

To build a specific target, provide it as an argument

To see the actions Make will run when building a target, without running the actions, use the --dry-run flag

: separates the target and the dependencies.

• Actions are indented using the TAB character, not 8 spaces.

If any dependency does not exist then Make will look for a rule to build it.

The order of rebuilding dependencies is arbitrary.

Dependencies must form a directed acyclic graph.

Backslash,\, the line continuation character, allows you to split up a list of dependencies or an action over multiple lines, to make them easier to read.

Phony targets are a short-hand for sequences of actions.

Prefix an action by @ to instruct Make not to print that action.

In Make 3.81, the default target can be explicitly set using the special variable .DEFAULT_GOAL

automatic variableA variable whose value is automatically redefined for each rule. Make’s automatic variables include $@, which holds the rule’s target, $^, which holds its dependencies, and, $<, which holds the first of its dependencies, and $*, which holds the stem with which the pattern was matched. Automatic variables are typically used in pattern rules.

incremental buildThe feature of a build manager by which it only rebuilds files that, either directory or indirectly, depend on a file that was changed.

pattern rule is a rule that specifies a general way to build or update an entire class of files in the same way.

A directory’s timestamp is not automatically updated when files are copied into it.

sed (stream editor) is a Unix utility that parses and transforms text, using a simple, compact programming language.

grep < pattern > < filenames > # looks for the string in the files

grep -r < pattern > < dir > # search recursively for pattern in directory