Execute a program or call a system command in Python

In this Python tutorial, we will see how to execute an external program or call a system command in Python.

Table Of Contents

Let’s dive into our tutorial.

What is a System command

A System command in Python is used to run executable binaries to do a particular task.

Examples of System commands

1.  dir: The dir command is a System Command used to display all files and subfolders present in directory
2.  ipconfig : The ipconfig command is used to display all network information.
3.  mkdir : The mkdir command is used to create new directory or folder in the filesystem.

There are the multiple ways to execute a program or call a system command using Python. Let’s discuss them one by one.

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Run system command using call() function of subprocess module

The subprocess module has a call() function. It is used to run the system commands in Python. The call() method runs a command, waits for the command to complete, then returns the return code.

Syntax:

subprocess.run(command, shell)
  • Parameters:
    • command = system command.
    • shell = boolean value, to specify use shell or not.
  • Returns:
    • Returns return code.

Approach

  1. Import subprocess library.
  2. Pass the system command to call() method and set shell=True.
  3. The output will be printed

Example:

import subprocess

# Passing the command to call() method
subprocess.call("dir", shell=True)

Output:

 Volume in drive C is OS
 Volume Serial Number is 5CA3-488D

 Directory of C:\Users\shiresha\Desktop\geeks_dir

21-05-2022  20:31    <DIR>          .
21-05-2022  20:31    <DIR>          ..
05-03-2022  14:30    <DIR>          question1
17-03-2022  21:53    <DIR>          question10
22-03-2022  15:24    <DIR>          question11
25-03-2022  13:49    <DIR>          question12
22-03-2022  17:59    <DIR>          question13
25-03-2022  13:52    <DIR>          question14
07-04-2022  21:51    <DIR>          question15
20-04-2022  08:59    <DIR>          question16
04-05-2022  09:24    <DIR>          question17
29-04-2022  17:28    <DIR>          question18
04-05-2022  09:24    <DIR>          question19
24-02-2022  20:23    <DIR>          question2
02-05-2022  07:18    <DIR>          question20
08-05-2022  13:23    <DIR>          question21
07-05-2022  20:47    <DIR>          question22
08-05-2022  14:30    <DIR>          question23
12-05-2022  20:31    <DIR>          question24
21-05-2022  19:51    <DIR>          question25
23-02-2022  22:42    <DIR>          question3
05-03-2022  15:36    <DIR>          question4
07-03-2022  09:51    <DIR>          question5
07-03-2022  14:38    <DIR>          QUESTION6
12-03-2022  10:18    <DIR>          question7
12-03-2022  11:18    <DIR>          question8
13-03-2022  14:24    <DIR>          question9
09-05-2022  08:59    <DIR>          temp
               1 File(s)            355 bytes
              28 Dir(s)  41,057,894,400 bytes free

Run system command using run() function of subprocess module

The subprocess module has a run() function. It is used to run the system commands in python. The run() method runs a command, waits for the command to complete, then returns the return code.

Syntax:

subprocess.run()(command, shell)
  • Parameters:
    • command = system command.
    • shell = boolean value, to specify use shell or not.
  • Returns:
    • Returns return code.

Approach

  1. Import subprocess library.
  2. Pass the system command to run() method and set shell=True.
  3. The output will be printed

Example:

import subprocess

# Pass the command to run() method
subprocess.run("dir", shell=True)

Output:

 Volume in drive C is OS
 Volume Serial Number is 5CA3-488D

 Directory of C:\Users\shiresha\Desktop\geeks_dir

21-05-2022  20:31    <DIR>          .
21-05-2022  20:31    <DIR>          ..
05-03-2022  14:30    <DIR>          question1
17-03-2022  21:53    <DIR>          question10
22-03-2022  15:24    <DIR>          question11
25-03-2022  13:49    <DIR>          question12
22-03-2022  17:59    <DIR>          question13
25-03-2022  13:52    <DIR>          question14
07-04-2022  21:51    <DIR>          question15
20-04-2022  08:59    <DIR>          question16
04-05-2022  09:24    <DIR>          question17
29-04-2022  17:28    <DIR>          question18
04-05-2022  09:24    <DIR>          question19
24-02-2022  20:23    <DIR>          question2
02-05-2022  07:18    <DIR>          question20
08-05-2022  13:23    <DIR>          question21
07-05-2022  20:47    <DIR>          question22
08-05-2022  14:30    <DIR>          question23
12-05-2022  20:31    <DIR>          question24
21-05-2022  19:51    <DIR>          question25
23-02-2022  22:42    <DIR>          question3
05-03-2022  15:36    <DIR>          question4
07-03-2022  09:51    <DIR>          question5
07-03-2022  14:38    <DIR>          QUESTION6
12-03-2022  10:18    <DIR>          question7
12-03-2022  11:18    <DIR>          question8
13-03-2022  14:24    <DIR>          question9
09-05-2022  08:59    <DIR>          temp
               1 File(s)            355 bytes
              28 Dir(s)  41,057,894,400 bytes free

Run system command using system() function of os module

The os module has a system() function. It is used to run the system commands in python.

Syntax:

os.system(command)
  • Parameters:
    • command = system command to be executed
  • Returns:
    • Returns value returned by the system shell after running command.

Approach

  1. Import os library.
  2. Pass the system command to system() method.
  3. The system method() return the value returned by the system shell after running command.

Example:

import os

# Pass the system command to system method
os.system("dir")

Output:

 Volume in drive C is OS
 Volume Serial Number is 5CA3-488D

 Directory of C:\Users\shiresha\Desktop\geeks_dir

21-05-2022  20:31    <DIR>          .
21-05-2022  20:31    <DIR>          ..
05-03-2022  14:30    <DIR>          question1
17-03-2022  21:53    <DIR>          question10
22-03-2022  15:24    <DIR>          question11
25-03-2022  13:49    <DIR>          question12
22-03-2022  17:59    <DIR>          question13
25-03-2022  13:52    <DIR>          question14
07-04-2022  21:51    <DIR>          question15
20-04-2022  08:59    <DIR>          question16
04-05-2022  09:24    <DIR>          question17
29-04-2022  17:28    <DIR>          question18
04-05-2022  09:24    <DIR>          question19
24-02-2022  20:23    <DIR>          question2
02-05-2022  07:18    <DIR>          question20
08-05-2022  13:23    <DIR>          question21
07-05-2022  20:47    <DIR>          question22
08-05-2022  14:30    <DIR>          question23
12-05-2022  20:31    <DIR>          question24
21-05-2022  19:51    <DIR>          question25
23-02-2022  22:42    <DIR>          question3
05-03-2022  15:36    <DIR>          question4
07-03-2022  09:51    <DIR>          question5
07-03-2022  14:38    <DIR>          QUESTION6
12-03-2022  10:18    <DIR>          question7
12-03-2022  11:18    <DIR>          question8
13-03-2022  14:24    <DIR>          question9
09-05-2022  08:59    <DIR>          temp
               1 File(s)            355 bytes
              28 Dir(s)  41,057,894,400 bytes free

Run system command using popen() function of os module

The os module has a popen() function. It is used to run the system commands in python.

Syntax:

os.popen(command)
  • Parameters:
    • command = system command to be executed
  • Returns:
    • Returns a file object connected to the pipe.

Approach

  1. Import os library.
  2. Pass the system command to popen() method.
  3. The popen method will return a file object and read it using the read() method.

Example:

import os

# Pass the system command to popen method
print(os.popen("dir").read())

Output:

 Volume in drive C is OS
 Volume Serial Number is 5CA3-488D

 Directory of C:\Users\shiresha\Desktop\geeks_dir

21-05-2022  20:31    <DIR>          .
21-05-2022  20:31    <DIR>          ..
05-03-2022  14:30    <DIR>          question1
17-03-2022  21:53    <DIR>          question10
22-03-2022  15:24    <DIR>          question11
25-03-2022  13:49    <DIR>          question12
22-03-2022  17:59    <DIR>          question13
25-03-2022  13:52    <DIR>          question14
07-04-2022  21:51    <DIR>          question15
20-04-2022  08:59    <DIR>          question16
04-05-2022  09:24    <DIR>          question17
29-04-2022  17:28    <DIR>          question18
04-05-2022  09:24    <DIR>          question19
24-02-2022  20:23    <DIR>          question2
02-05-2022  07:18    <DIR>          question20
08-05-2022  13:23    <DIR>          question21
07-05-2022  20:47    <DIR>          question22
08-05-2022  14:30    <DIR>          question23
12-05-2022  20:31    <DIR>          question24
21-05-2022  19:51    <DIR>          question25
23-02-2022  22:42    <DIR>          question3
05-03-2022  15:36    <DIR>          question4
07-03-2022  09:51    <DIR>          question5
07-03-2022  14:38    <DIR>          QUESTION6
12-03-2022  10:18    <DIR>          question7
12-03-2022  11:18    <DIR>          question8
13-03-2022  14:24    <DIR>          question9
09-05-2022  08:59    <DIR>          temp
               1 File(s)            355 bytes
              28 Dir(s)  41,057,894,400 bytes free

Summary

We learned about four different ways to run a external program or a system command in Python. Happy Coding.

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