What is the return value of os system in Python

Question

I came across this    gt  gt  gt  import os  gt  gt  gt  os system  ls   file txt README 0   What is return value of os system     Why I get 0

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Based on the answer of  AlokThakur  thanks    def run system command command       return value   os system command        Calculate the return value code     return value   int bin return value  replace  quot 0b quot    quot  quot   rjust 16   0    8   2      if return value    0          raise RuntimeError f The system command n command  nexited with return code  return value

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The return value of os system is OS-dependant   On Unix  the return value is a 16-bit number that contains two different pieces of information  From the documentation      a 16-bit number  whose low byte is the signal number that killed the process  and whose high byte is the exit status  if the signal number is zero    So if the signal number  low byte  is 0  it would  in theory  be safe to shift the result by 8 bits  result  gt  gt  8  to get the error code  The function os WEXITSTATUS does exactly this  If the error code is 0  that usually means that the process exited without errors   On Windows  the documentation specifies that the return value of os system is shell-dependant  If the shell is cmd exe  the default one   the value is the return code of the process  Again  0 would mean that there weren t errors   For others error codes    on Linux on Windows

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os system   returns some unix output  not the command output  So  if there is no error then exit code written as 0

User · Answer

You might want to use return value   os popen  ls   read    instead  os system only returns the error value  The os popen is a neater wrapper for subprocess Popen function as is seen within the python source code

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os system  command   returns a 16 bit number  which first 8 bits from left lsb  talks about signal used by os to close the command  Next 8 bits talks about return code of command    00000000    00000000 exit code   signal num   Example 1 - command exit with code 1  os system  command    it returns 256 256 in 16 bits -  00000001 00000000 Exit code is 00000001 which means 1   Example 2 - command exit with code 3  os system  command     it returns 768 768 in 16 bits  - 00000011 00000000 Exit code is 00000011 which means 3   Now try with signal -  Example 3 - Write a program which sleep for long time use it as command in os system   and then kill it by kill -15 or kill -9  os system  command    it returns signal num by which it is killed 15 in bits - 00000000 00001111 Signal num is 00001111 which means 15   You can have a python program as command    python command py   import sys sys exit n     here n would be exit code   In case of c or c   program you can use return from main   or exit n  from any function     Note - This is applicable on unix     On Unix  the return value is the exit status of the process encoded in   the format specified for wait    Note that POSIX does not specify the   meaning of the return value of the C system   function  so the return   value of the Python function is system-dependent       os wait        Wait for completion of a child process  and return a tuple containing its pid and exit status indication  a 16-bit number  whose   low byte is the signal number that killed the process  and whose high   byte is the exit status  if the signal number is zero   the high bit   of the low byte is set if a core file was produced   Availability  Unix

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On Unix  the return value is the exit   status of the process encoded in the   format specified for wait    Note that   POSIX does not specify the meaning of   the return value of the C system     function  so the return value of the   Python function is system-dependent     http   docs python org library os html os system  There is no error  so the exit code is zero

[python] What is the return value of os.system() in Python?

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