Clear terminal in Python [duplicate]

Answer 1

For Windows, Mac and Linux, you can use the following code:

import subprocess, platform

if platform.system()=="Windows":
    subprocess.Popen("cls", shell=True).communicate() #I like to use this instead of subprocess.call since for multi-word commands you can just type it out, granted this is just cls and subprocess.call should work fine 
else: #Linux and Mac
    print("\033c", end="")

jamesnotjim tested print("\033c", end="") for Mac, and I tested it on Linux and Windows (it doesn't work for Windows, hence the other code that calls cls). I don't remember who it was I first saw use print("\033c") and/or the printf version: subprocess.Popen("printf '\033c'", shell=True).communicate().

rolika pointed out that end="" will prevent it from printing a new line afterward.

Answer 2

This function works in gnome-terminal because, by default, it recognizes ANSI escape sequences. It gives you a CLEAN PROMPT rows_max distance from the bottom of the terminal, but also precisely from where it was called. Gives you complete control over how much to clear.

def clear(rows=-1, rows_max=None, *, calling_line=True, absolute=None,
          store_max=[]):
    """clear(rows=-1, rows_max=None)
clear(0, -1) # Restore auto-determining rows_max
clear(calling_line=False) # Don't clear calling line
clear(absolute=5) # Absolutely clear out to 5 rows up"""
    from os import linesep
    if rows_max and rows_max != -1:
        store_max[:] = [rows_max, False]
    elif not store_max or store_max[1] or rows_max == -1 or absolute:
        try:
            from shutil import get_terminal_size
            columns_max, rows_max = get_terminal_size()
        except ImportError:
            columns_max, rows_max = 80, 24
        if absolute is None:
            store_max[:] = [rows_max, True]
    if store_max:
        if rows == -1:
            rows = store_max[0]
        elif isinstance(rows, float):
            rows = round(store_max[0] * rows)
        if rows > store_max[0] - 2:
            rows = store_max[0] - 2
    if absolute is None:
        s = ('\033[1A' + ' ' * 30 if calling_line else '') + linesep * rows
    else:
        s = '\033[{}A'.format(absolute + 2) + linesep
        if absolute > rows_max - 2:
            absolute = rows_max - 2
        s += (' ' * columns_max + linesep) * absolute + ' ' * columns_max
        rows = absolute
    print(s + '\033[{}A'.format(rows + 1))

Implementation:

clear() # Clear all, TRIES to automatically get terminal height
clear(800, 24) # Clear all, set 24 as terminal (max) height
clear(12) # Clear half of terminal below if 24 is its height
clear(1000) # Clear to terminal height - 2 (24 - 2)
clear(0.5) # float factor 0.0 - 1.0 of terminal height (0.5 * 24 = 12)
clear() # Clear to rows_max - 2 of user given rows_max (24 - 2)
clear(0, 14) # Clear line, reset rows_max to half of 24 (14-2)
clear(0) # Just clear the line
clear(0, -1) # Clear line, restore auto-determining rows_max
clear(calling_line=False) # Clear all, don't clear calling line
clear(absolute=5) # Absolutely clear out to 5 rows up

Parameters: rows is the number of clear text rows to add between prompt and bottom of terminal, pushing everything up. rows_max is the height of the terminal (or max clearing height) in text rows, and only needs to be set once, but can be reset at any time. *, in the third parameter position means all following parameters are keyword only (e.g., clear(absolute=5)). calling_line=True (default) works better in Interactive mode. calling_line=False works better for text-based, terminal applications. absolute was added to try to fix glitchy gap problems in Interactive mode after reducing size of terminal, but can also be used for terminal applications. store_max is just for secret, "persistent" storage of rows_max value; don't explicitly use this parameter. (When an argument is not passed for store_max, changing the list contents of store_max changes this parameter's default value. Hence, persistent storage.)

Portability: Sorry, this doesn't work in IDLE, but it works >> VERY COOL << in Interactive mode in a terminal (console) that recognizes ANSI escape sequences. I only tested this in Ubuntu 13.10 using Python 3.3 in gnome-terminal. So I can only assume portability is dependant upon Python 3.3 (for the shutil.get_terminal_size() function for BEST results) and ANSI recognition. The print(...) function is Python 3. I also tested this with a simple, text-based, terminal Tic Tac Toe game (application).

For use in Interactive mode: First copy and paste the copy(...) function in Interactive mode and see if it works for you. If so, then put the above function into a file named clear.py . In the terminal start python, with 'python3'. Enter:

>>> import sys
>>> sys.path
['', '/usr/lib/python3.3', ...

Now drop the clear.py file into one of the path directories listed so that Python can find it (don't overwrite any existing files). To easily use from now on:

>>> from clear import clear
>>> clear()
>>> print(clear.__doc__)
clear(rows=-1, rows_max=None)
clear(0, -1) # Restore auto-determining rows_max
clear(calling_line=False) # Don't clear calling line
clear(absolute=5) # Absolutely clear out to 5 rows up

For use in a terminal application: Put the copy(...) function into a file named clear.py in the same folder with your main.py file. Here is a working abstract (skeleton) example from a Tic Tac Toe game application (run from terminal prompt: python3 tictactoe.py):

from os import linesep

class TicTacToe:    
    def __init__(self):
        # Clear screen, but not calling line
        try:
            from clear import clear
            self.clear = clear
            self.clear(calling_line=False)
        except ImportError:
            self.clear = False
        self.rows = 0    # Track printed lines to clear

        # ...
        self.moves = [' '] * 9

    def do_print(self, *text, end=linesep):
        text = list(text)
        for i, v in enumerate(text[:]):
            text[i] = str(v)
        text = ' '.join(text)
        print(text, end=end)
        self.rows += text.count(linesep) + 1

    def show_board(self):
        if self.clear and self.rows:
            self.clear(absolute=self.rows)
        self.rows = 0
        self.do_print('Tic Tac Toe')
        self.do_print('''   |   |
 {6} | {7} | {8}
   |   |
-----------
   |   |
 {3} | {4} | {5}
   |   |
-----------
   |   |
 {0} | {1} | {2}
   |   |'''.format(*self.moves))

    def start(self):
        self.show_board()
        ok = input("Press <Enter> to continue...")
        self.moves = ['O', 'X'] * 4 + ['O']
        self.show_board()
        ok = input("Press <Enter> to close.")

if __name__ == "__main__":
    TicTacToe().start()

Explanation: do_print(...) on line 19 is a version of print(...) needed to keep track of how many new lines have been printed (self.rows). Otherwise, you would have to self.rows += 1 all over the place where print(...) is called throughout the entire program. So each time the board is redrawn by calling show_board() the previous board is cleared out and the new board is printed exactly where it should be. Notice self.clear(calling_line=False) on line 9 basically pushes everything up RELATIVE to the bottom of the terminal, but does not clear the original calling line. In contrast, self.clear(absolute=self.rows) on line 29 absolutely clears out everything self.rows distance upward, rather than just pushing everything upward relative to the bottom of the terminal.

Ubuntu users with Python 3.3: Put #!/usr/bin/env python3 on the very first line of the tictactoe.py file. Right click on the tictactoe.py file => Properties => Permissions tab => Check Execute: Allow executing file as program. Double click on the file => Click Run in Terminal button. If an open terminal's current directory is that of the tictactoe.py file, you can also start the file with ./tictactoe.py.

Answer 3

The accepted answer is a good solution. The problem with it is that so far it only works on Windows 10, Linux and Mac. Yes Windows (known for it lack of ANSI support)! This new feature was implemented on Windows 10 (and above) which includes ANSI support, although you have to enable it. This will clear the screen in a cross platform manner:

import os

print ('Hello World')
os.system('') 
print ("\x1B[2J")

On anything below Windows 10 however it returns this:

[2J

This is due to the lack of ANSI support on previous Windows builds. This can however, be solved using the colorama module. This adds support for ANSI characters on Windows:

ANSI escape character sequences have long been used to produce colored terminal text and cursor positioning on Unix and Macs. Colorama makes this work on Windows, too, by wrapping stdout, stripping ANSI sequences it finds (which would appear as gobbledygook in the output), and converting them into the appropriate win32 calls to modify the state of the terminal. On other platforms, Colorama does nothing.

So here is a cross platform method:

import sys

if sys.platform == 'win32':
    from colorama import init
    init()

print('Hello World')

print("\x1B[2J")

Or print(chr(27) + "[2J") used instead of print("\x1B[2J").

---

@poke answer is very insecure on Windows, yes it works but it is really a hack. A file named cls.bat or cls.exe in the same dictionary as the script will conflict with the command and execute the file instead of the command, creating a huge security hazard.

One method to minimise the risk could be to change the location of where the cls command is called:

import os
os.system('cd C:\\Windows|cls' if os.name == 'nt' else 'clear')

This will change the Currant Dictionary to C:\Window (backslash is important here) then execute. C:\Windows is always present and needs administration permissions to write there making it a good for executing this command with minimal risk. Another solution is to run the command through PowerShell instead of Command Prompt since it has been secured against such vulnerabilities.

There are also other methods mentioned in this question: Clear screen in shell which may also be of use.

Answer 4

By default, os.system("clear")/os.system("cls") will return an int type as 0. We can completely clear the screen by assigning it to a variable and deleting that.

def clear():
    if (os.name == 'nt'):    
        c = os.system('cls')
    else:
        c = os.system('clear')
    del c  # can also omit c totally

#clear()

Answer 5

If you are on a Linux/UNIX system then printing the ANSI escape sequence to clear the screen should do the job. You will also want to move cursor to the top of the screen. This will work on any terminal that supports ANSI.

import sys
sys.stderr.write("\x1b[2J\x1b[H")

This will not work on Windows unless ANSI support has been enabled. There may be an equivalent control sequence for Windows, but I do not know.

Answer 6

If all you need is to clear the screen, this is probably good enough. The problem is there's not even a 100% cross platform way of doing this across linux versions. The problem is the implementations of the terminal all support slightly different things. I'm fairly sure that "clear" will work everywhere. But the more "complete" answer is to use the xterm control characters to move the cursor, but that requires xterm in and of itself.

Without knowing more of your problem, your solution seems good enough.