Import command in linux

команда импорта в Linux с примерами

Команда import в системе Linux используется для захвата скриншота любой активной страницы, которая у нас есть, и выводит ее в виде файла изображения. Вы можете захватить одно окно, если хотите, или вы можете взять весь экран, или вы можете сделать снимок экрана любой прямоугольной части экрана.

Синтаксис:

Команда импорта с опцией справки: она напечатает общий синтаксис команды вместе с различными опциями, которые можно использовать с командой импорта, а также даст краткое описание каждой опции.

Пример:

Параметры:

-adjoin: с помощью этой опции вы сможете объединять изображения в один файл из нескольких изображений.

-border: эта опция используется для включения границы окна в выходное изображение.

-descend: эта опция позволяет получить изображение по убыванию иерархии окон.

-frame: эта опция будет включать фрейм оконного менеджера.

-identify: эта опция используется для определения формата и характеристик изображения.

-quiet: эта опция подавит все предупреждающие сообщения.

-monitor: эта опция будет контролировать прогресс.

-screen: эта опция выберет изображение из корневого окна.

Другие доступные параметры в команде импорта:

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import command in Linux with Examples

import command in Linux system is used for capturing a screenshot for any of the active pages we have and it gives the output as an image file. You can capture a single window if you want or you can take the entire screen or you can take a screenshot of any rectangular portion of the screen.

Syntax:

import command with help option: It will print the general syntax of the command along with the various options that can be used with the import command as well as gives a brief description about each option.

Example:

Options:

-adjoin: With the help of this option you will be able to join images into a single multi-image file.

-border: This option is used to include window border in the output image.

-descend: This option obtain image by descending window hierarchy.

-frame: This option will include window manager frame.

-identify: This option is being used to identify the format and characteristics of the image.

-quiet: This option will suppress all warning messages.

-monitor: This option will monitor the progress.

-screen: This option will select image from root window.

Other available options in the import command are:

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Python Import Command

The import command in Python is used to get access to other modules. Modules are the same as a code library in Java, C, C++, or C#. A module typically involves a set of functions and variables. When we need to include or use these functions of modules in our code, we can simply import the module by using the import command and we can easily invoke the module functions and variables. The import command is the simplest and common way of including modules into your code.

Python comes up with many built-in modules that we can include in our code easily. We can also create our module by just saving the Python code file with the .py extension.

In this article, we will learn that how we can import our own and built-in modules in Python. Spyder3 editor is used to creating and running the Python scripts.

How to use the import command

We use the import keyword to import the modules in Python. While importing the module in our code, we write the module name with import command in this way:

Import Python built-in modules

Python comes up with many built-in modules. Math module is one of the common modules that is used to perform the mathematical functions.

Let’s import the math module by using the import keyword and use its functions to perform mathematical calculations. When we access any function from a module, we write the name of the module and put a dot and write the name of the function like that:

module_name. function_name ( )
# importing the math module
import math
# printing the value of pi constant
print ( «The value of PI is: » , math . pi )

# calculating the factorial of a number using factorial function
print ( «The factorial of number 5 is: » , math . factorial ( 5 ) )

# calculating the log of a number using the log function
print ( «The log of 10 is: » , math . log ( 10 ) )

# printing the value of Euler’s number
print ( «The value of Euler’s number is: » , math . e )

# calculating the radians from degrees
rad = math . radians ( 90 )
print ( «The radians of 90 is: » , rad )

# calculating the sin value
print ( «The sin of 90 is: » , math . sin ( 90 ) )

# calculating the coa value
print ( «The cos of 90 is: » , math . cos ( 90 ) )

# calculating the tan value
print ( «The tan of 90 is: » , math . tan ( 90 ) )

Output

The output is displayed on the Python console.

In some cases, if we want to import only a specific function or a constant from a module, we can do in this way:

For example, only the pi constant from the math module can be imported in this way

Let’s see an example of it.

Output

The output is displayed on the Python console.

All the functions and constants can be imported in this way:

In the case of the math module it would be like this:

# importing only pi value from the math module
from math import *
# Now we don’t need to specify math with the constant and function
# printing the value of pi constant
print ( «The value of PI is: » , pi )

# calculating the value of sin 90
print ( «The value of sin 90 is:» , sin ( 90 ) )

# calculating the factorial of 8
print ( «The factorial of 8 is: » , factorial ( 8 ) )

Output

The output is displayed on the Python console.

The import command searches for the module name if the module is not found, then it shows an error. Let’s try to import the module “Tokenizer”.

Output

In the output, you can see that it throws an error “ModuleNotFoundError”.

Create your module

To create your module, create a python file, write the code, and save it with .py extension.

Let’s see an example of it.

Example

We have created a new module named “calculate.py”. It has a function, which takes two numbers as an argument and returns it sum.

Now let’s create another Python file (test.py) and call the “calculator” module in that file.

Output

The output is displayed on the Python console.

Now let’s modify the calculator module file and create two variables here.

Let’s try to access the variables of calculator module in test.py

Output

The output is displayed on the Python console.

We can also create an alias while importing a module by using the “as” keyword and it will work fine.

Output

In the output, you can see that it works fine and does not show any type of error.

We can use the Python built-in dir() function to list down all the available functions and variables of a module.

Output

The output shows all the available variables and functions of the “calculator” module.

Conclusion

This article explains the Python import command in detail with the help of simple examples. The import command is used to call the built-in and user-defined modules in Python files.

About the author

Kamran Sattar Awaisi

I am a software engineer and a research scholar. I like to write article and make tutorial on various IT topics including Python, Cloud Computing, Fog Computing and Deep Learning. I love to use Linux based operating systems.

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Equivalent of import libraries in Linux

In Windows C++ when you want to link against a DLL you must supply an import library. But in GNU build system when you want to link against .so files which are the equivalent of dll you don’t. Why is this? Is there an equivalent of Windows import libraries.

Note: I don’t speak about the case where you use GNU C++ in Windows where you have to use import libraries as well. The splitting line is between Windows C++ and Linux C++.

2 Answers 2

The linking model is different in Windows and in Linux. Read Levine’s book Linkers and loaders (on Linux, every public symbol of a library is exported, unless you play visibility tricks; on Windows, that is not the case, and exported symbols need to be explicited).

The C++11 standard (read n3337) don’t mention dynamic linking. It is an implementation detail.

The future C++20 could have modules.

There is no «import libraries» in Linux.

On Linux, plugins are loaded (and handled differently than on Windows) by the dynamic loader. See ld-linux(8), dlopen(3), dlsym(3), elf(5)

See also C++ dlopen mini howto. Read also about the Visibility function attribute. See also this question.

.so files which are the equivalent of dll

A Linux shared object (ELF .so file) is not exactly equivalent to a Windows DLL. Read the references given above.

I also recommend reading Operating Systems: Three Easy Pieces and the old Advanced Linux Programming (both are freely downloadable). Later read syscalls(2) and the pages referenced from there.

Be also aware that Linux is free software, so you can download and study the source code of most of its components.

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How can I import a database using command line?

I am using Ubuntu 14.04. I want to import my database which is located on the server /var/www/backup.zip . Also I’ve SSH access using Putty. Noted that MySQL and phpMyadmin are installed on the server.

When I run this command

nothing happens. A newline shows which starts with -> .

What should I do now?

2 Answers 2

I believe the format is:

From within mysql:

The main problem is that you’re trying to run a bash command from within mysql. If you run that command at the regular terminal prompt the format of the command is correct.

The second issue is that you have a zip file and not a SQL file so you need to unzip it first.

How do I load a sql.gz file to my database? (on Server Fault) explains most of what you need. My answer there should work here too with a slight modification:

unzip -p unzips to a pipe, so that you can pipe that into your database command. Make sure the zip file only contains one sql file.

mysql -u root -p mydb is going to prompt you for a password (the -p without a value) and then attempt to pipe in the file data to mydb — change the mydb to your own database. You shouldn’t specify the password in the command line as it then remains in your command history.

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