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programming:python:run_system_command [2024/02/10 09:47] – niziakprogramming:python:run_system_command [2024/02/23 08:46] (current) – niziak
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 +====== system / popen / exec ======
  
 +In general: run system commands.
 +
 +Current recommended way is to use [[https://docs.python.org/3/library/subprocess.html|subprocess]] module. This module intends to **replace several older** modules and functions:
 +<code python>
 +os.system
 +os.spawn*
 +</code>
 +
 +[[https://docs.python.org/3/library/subprocess.html#replacing-older-functions-with-the-subprocess-module|Replacing Older Functions with the subprocess Module]]
 +
 +[[https://docs.python.org/3/library/subprocess.html#replacing-os-system|Replacing os.system()]]
 +
 +Features:
 +  * possible to execute in shell:
 +    * all command and params can be specified as string not list
 +    * multiple commands can be executed at once; shell pipes usage possible
 +  * configurable check for return codes or output
 +
 +Parameters:
 +  * [[https://docs.python.org/3.10/library/io.html#io-text-encoding|io-text-encoding]]
 +  * 
 +
 +Examples:
  
 <code python> <code python>
Line 14: Line 38:
 data = meta_data.decode('utf-8', errors ="backslashreplace") data = meta_data.decode('utf-8', errors ="backslashreplace")
 </code> </code>
 +
 +<code python>
 +return subprocess.check_output(
 +                [self.FW_PRINTENV, '-n', var],
 +                stderr=subprocess.STDOUT, encoding='ascii').strip()
 +...                
 +return subprocess.check_call([self.FW_SETENV, var, value])                
 +</code>
 +