My understanding is the operation of the two are different:
Documentation -
Quote:
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.
Hi,
I am having a trivial doubt. Please see the below pipeline code sequence.
command1 | (command 2; commend 3)
I am aware that the command that follows pipe will run in the sub shell by the Unix kernel. But how about here? Since these set of commands are grouped under "parantheses", will... (6 Replies)
I have a cron on a Linux server that isn't executing properly.
CRON (with specific info replaced):
MAILTO=emailaddress@server.com
*/2 * * * * python /data/site/cron.py
OUTPUT:
python: can't open file '/data/site/cron.py
': No such file or directoryAdditional info
- The python path is... (3 Replies)
Hi Guys,
Just a question about subprocesses.. Lately one of our servers has started to throw out the following error:
SYSTEM ERROR: Too many subprocesses, cannot fork. Errno=12
We've already increased the threshold twice. Its now up to 8000 and the swap space has also been increased. We... (6 Replies)
Hi,
I am trying to run a shell script using subprocess in python.
I can run simple script with arguments using subprocess.But I am not able to embed xterm in subrocess command.
#!/usr/bin/python
import subprocess
subprocess.call()
Above code gives me error.
Please help me in... (2 Replies)
Hi guys,
I'm learning python and perl and i was trying to run from python a perl script using the subprocess module.
I have an issue that i don't understand regarding this.
I run this code:
#!/usr/bin/python
import subprocess
p2 = subprocess.Popen(,stdout=subprocess.PIPE)
output2 =... (2 Replies)
Greetings!
I set up a basic threading specimen which does the job:#!/usr/bin/python
import threading
class a(threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
def run(self):
print("thread a finished")
class b(threading.Thread):
... (0 Replies)
Hi Experts,
Good morning.
I am trying to convert my hello.py to hello .exe file.
I followed the steps as mentioned in the documentation but getting errors in the end. Please help.
What I did as below--
Created hello.py file
print ("Hello world!")
raw_input('')
Then... (0 Replies)
I have a string like below
Note: I have have a single to any number of comma "," seperated string assigned to jdbc_trgt variable.
I need to split jdbc_trgt using comma(,) as the delimiter.
I tried the below but it fails as i dont know how can i read each split string iterately.
for... (4 Replies)
Discussion started by: mohtashims
4 Replies
LEARN ABOUT OSX
tcl_waitpid
Tcl_DetachPids(3) Tcl Library Procedures Tcl_DetachPids(3)__________________________________________________________________________________________________________________________________________________NAME
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
TclTcl_DetachPids(3)