Python popen command Wait until the command is finished

Question

I have a script where I launch with popen a shell command  The problem is that the script doesn t wait until that popen command is finished and go continues right away   om points   os popen command   w           How can I tell to my Python script to wait until the shell command has finished

User · Answer

I think process communicate   would be suitable for output having small size  For larger output it would not be the best approach

User · Answer

You can you use subprocess to achieve this   import subprocess   This command could have multiple commands separated by a new line  n some command    export PATH  PATH   server sample mo app bin  n customupload abc txt   p   subprocess Popen some command  stdout subprocess PIPE  shell True    output  err    p communicate       This makes the wait possible p status   p wait     This will give you the output of the command being executed print  Command output      output

User · Answer

wait   works fine for me  The subprocesses p1  p2 and p3 are executed at the same  Therefore  all processes are done after 3 seconds      import subprocess  processes       p1   subprocess Popen  sleep 3   stdout subprocess PIPE  shell True  p2   subprocess Popen  sleep 3   stdout subprocess PIPE  shell True  p3   subprocess Popen  sleep 3   stdout subprocess PIPE  shell True   processes append p1  processes append p2  processes append p3   for p in processes      if p wait      0          print  There was an error    print  all processed finished

User · Answer

Force popen to not continue until all output is read by doing   os popen command  read

User · Answer

Let the command you are trying to pass be   os system  x     then you covert it to a statement  t   os system  x     now the python will be waiting for the output from the commandline so that it could be assigned to the variable t

User · Answer

What you are looking for is the wait method

User · Answer

Depending on how you want to work your script you have two options  If you want the commands to block and not do anything while it is executing  you can just use subprocess call    start and block until done subprocess call  data  om points      gt    diz  d     points xml      If you want to do things while it is executing or feed things into stdin  you can use communicate after the popen call    start and process things  then wait p   subprocess Popen  data  om points      gt    diz  d     points xml    print  Happens while running  p communicate    now wait plus that you can send commands to process   As stated in the documentation  wait can deadlock  so communicate is advisable

[python] Python popen command. Wait until the command is finished

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