Full Discussion: [Python] - subprocess issue
Top Forums Programming [Python] - subprocess issue Post 303038959 by jim mcnamara on Wednesday 18th of September 2019 10:23:23 AM
My understanding is the operation of the two are different:

Documentation -
check_call() returns as soon as /bin/sh process exits, it does not wait for child processes to complete

check_output() waits until all output is read. When (and if) check_output inherits the stdin pipe then check_output() will wait until it exits, i.e., until the child process the inherited pipe. In other words it waits for the child process to end.
Try getting get rid of the shlex,
subprocess.check_output( [ "command" "parameter_1" ])

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Tcl_DetachPids(3)					      Tcl Library Procedures						 Tcl_DetachPids(3)


Tcl_DetachPids, Tcl_ReapDetachedProcs, Tcl_WaitPid - manage child processes in background SYNOPSIS
#include <tcl.h> Tcl_DetachPids(numPids, pidPtr) Tcl_ReapDetachedProcs() Tcl_Pid Tcl_WaitPid(pid, statusPtr, options) ARGUMENTS
int numPids (in) Number of process ids contained in the array pointed to by pidPtr. int *pidPtr (in) Address of array containing numPids process ids. Tcl_Pid pid (in) The id of the process (pipe) to wait for. int *statusPtr (out) The result of waiting on a process (pipe). Either 0 or ECHILD. int options (in) The options controlling the wait. WNOHANG specifies not to wait when checking the process. _________________________________________________________________ DESCRIPTION
Tcl_DetachPids and Tcl_ReapDetachedProcs provide a mechanism for managing subprocesses that are running in background. These procedures are needed because the parent of a process must eventually invoke the waitpid kernel call (or one of a few other similar kernel calls) to wait for the child to exit. Until the parent waits for the child, the child's state cannot be completely reclaimed by the system. If a parent continually creates children and doesn't wait on them, the system's process table will eventually overflow, even if all the children have exited. Tcl_DetachPids may be called to ask Tcl to take responsibility for one or more processes whose process ids are contained in the pidPtr array passed as argument. The caller presumably has started these processes running in background and does not want to have to deal with them again. Tcl_ReapDetachedProcs invokes the waitpid kernel call on each of the background processes so that its state can be cleaned up if it has exited. If the process has not exited yet, Tcl_ReapDetachedProcs does not wait for it to exit; it will check again the next time it is invoked. Tcl automatically calls Tcl_ReapDetachedProcs each time the exec command is executed, so in most cases it is not necessary for any code outside of Tcl to invoke Tcl_ReapDetachedProcs. However, if you call Tcl_DetachPids in situations where the exec command may never get executed, you may wish to call Tcl_ReapDetachedProcs from time to time so that background processes can be cleaned up. Tcl_WaitPid is a thin wrapper around the facilities provided by the operating system to wait on the end of a spawned process and to check a whether spawned process is still running. It is used by Tcl_ReapDetachedProcs and the channel system to portably access the operating sys- tem. KEYWORDS
background, child, detach, process, wait Tcl Tcl_DetachPids(3)

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