I have two long running functions which needs to be executed asynchronously. For simplicity, assume one function sends Mail to client every 10 seconds & other logs text file every two seconds.
I cannot use cron jobs to do this. Everything has to be in one script. Thus I have used infinite loops and sleep with & achieve asynchronous behavior.
Used to trap 'pkill -P $$' SIGINT SIGTERM to end all child processes(to end program) when user hits CTRL+Z (SIGINT) but this doesn't work. It again starts script execution even after pressing CTRL+Z.
How can I give user the ability to end program with keyboard clicks from same terminal?
Note: Those two functions are never ending until user manually stops the program.
echo "Press: CTRL+Z to Close program"
trap 'pkill -P $$' SIGINT SIGTERM
first_fun()
{
while :; do
echo "send Mail every 10 seconds"
sleep 10
done
}
second_fun()
{
while :; do
echo "log text file every 2 seconds"
sleep 2
done
}
first_fun &
second_fun &
Suggesting to use " to let the shell interpret $$. Like this:
trap "pkill -9 -P $$"
Also suggesting to kill all process running from current directory, because process ancestory is not always working (e.g using nohup command):
trap "pkill -9 -f $PWD"
Also suggesting to kill/stop a process with CTRL-C (the standard) and avoid CTRL-Z used for suspending processes.
When problem with your script was that the script exists after runs those two functions. So "$$" is no longer refers to the script. An easy fix is to put a wait at the end of the script. Also change to this might help
trap "pkill -P $$" INT TERM
But, what I would do is to kill those functions rather than killing the script:
echo "Press: CTRL+Z to Close program"
first_fun()
{
while :; do
echo "send Mail every 10 seconds"
sleep 10
done
}
second_fun()
{
while :; do
echo "log text file every 2 seconds"
sleep 2
done
}
_INTERRUPTED
_PID1
_PID2
interrupt()
{
# Do this once.
if [[ -z "$_INTERRUPTED" ]]; then
_INTERRUPTED='true'
kill -KILL "$_PID1"
kill -KILL "$_PID2"
fi
}
trap interrupt INT TERM EXIT
first_fun &
_PID1="$!"
second_fun &
_PID2="$!"
wait
I Have a script foo.sh that launches 5 process of bfoo.sh in background like this :
for i in {1..5}
do
./bfoo.sh &
done
wait
echo ok
and I use it like this :
./foo.sh
In foo.s after the for loop, I want to do something like i.e. for each process bfoo.sh terminated do
echo $PID_Terminated
To achieve this, you need to store the PID of each of the background process of bfoo.sh. The $! contains the process id that was last backgrounded by the shell. We append them one at a time to the array and iterate it over later
Remember this runs your background process one after the other since you have wait on each process id separately.
#!/usr/bin/env bash
pidArray=()
for i in {1..5}; do
./bfoo.sh &
pidArray+=( "$!" )
done
Now wait on each of the processes and in a loop
for pid in "${pidArray[#]}"; do
wait "$pid"
printf 'process-id: %d finished with code %d\n' "$pid" "$?"
done
I have additionally added the exit code of the background process $? when it finishes, so that any abnormal exit can be debugged.
I have two scripts, in which one is calling the other, and needs to kill it after some time. A very basic, working example is given below.
main_script.sh:
#!/bin/bash
cd "${0%/*}" #make current working directory the folder of this script
./record.sh &
PID=$!
# perform some other commands
sleep 5
kill -s SIGINT $PID
#wait $PID
echo "Finished"
record.sh:
#!/bin/bash
cd "${0%/*}" #make current working directory the folder of this script
RECORD_PIDS=1
printf "WallTimeStart: %f\n\n" $(date +%s.%N) >> test.txt
top -b -p $RECORD_PIDS -d 1.00 >> test.txt
printf "WallTimeEnd: %f\n\n" $(date +%s.%N) >> test.txt
Now, if I run main_script.sh, it will not nicely close record.sh on finish: the top command will keep on running in the background (test.txt will grow until you manually kill the top process), even though the main_script is finished and the record script is killed using SIGINT.
If I ctrl+c the main_script.sh, everything shuts down properly. If I run record.sh on its own and ctrl+c it, everything shuts down properly as well.
If I uncomment wait, the script will hang and I will need to ctrl+z it.
I have already tried all kinds of things, including using 'trap' to launch some cleanup script when receiving a SIGINT, EXIT, and/or SIGTERM, but nothing worked. I also tried bring record.sh back to the foreground using fg, but that did not help too. I have been searching for nearly a day now already, with now luck unfortunately. I have made an ugly workaround which uses pidof to find the top process and kill it manually (from main_script.sh), and then I have to write the "WallTimeEnd" statement manually to it as well from the main_script.sh. Not very satisfactory to me...
Looking forward to any tips!
Cheers,
Koen
Your issue is that the SIGINT is delivered to bash rather than to top. One option would be to use a new session and send the signal to the process group instead, like:
#!/bin/bash
cd "${0%/*}" #make current working directory the folder of this script
setsid ./record.sh &
PID=$!
# perform some other commands
sleep 5
kill -s SIGINT -$PID
wait $PID
echo "Finished"
This starts the sub-script in a new process group and the -pid tells kill to signal every process in that group, which will include top.
I am trying to write a bash script to run one process after another approximately 1024 times with different command line options. However one of the processes include an infinite loop and I am trying to kill that process before another iteration of the loop begins.
So here is what I tried so far (prog1 includes the infinite loop and I want to kill it when papi finishes running) :
#!/bin/bash
for (( i=0; i<32780; i+=32))
do
./prog1 $i &
pid=$!;
sleep 5s
./papi
kill -s 2 $pid
done
However it does not kill any prog1 instances, and of course it continues to create them at the beginning of each iteration. What am I doing wrong?
It kills a process before finishing:
pkill $!
for example:
telnet 192.168.1.1 1>/dev/null 2>&1 &
pkill $!
I have a bash script that launches a child process that crashes (actually, hangs) from time to time and with no apparent reason (closed source, so there isn't much I can do about it). As a result, I would like to be able to launch this process for a given amount of time, and kill it if it did not return successfully after a given amount of time.
Is there a simple and robust way to achieve that using bash?
P.S.: tell me if this question is better suited to serverfault or superuser.
(As seen in:
BASH FAQ entry #68: "How do I run a command, and have it abort (timeout) after N seconds?")
If you don't mind downloading something, use timeout (sudo apt-get install timeout) and use it like: (most Systems have it already installed otherwise use sudo apt-get install coreutils)
timeout 10 ping www.goooooogle.com
If you don't want to download something, do what timeout does internally:
( cmdpid=$BASHPID; (sleep 10; kill $cmdpid) & exec ping www.goooooogle.com )
In case that you want to do a timeout for longer bash code, use the second option as such:
( cmdpid=$BASHPID;
(sleep 10; kill $cmdpid) \
& while ! ping -w 1 www.goooooogle.com
do
echo crap;
done )
# Spawn a child process:
(dosmth) & pid=$!
# in the background, sleep for 10 secs then kill that process
(sleep 10 && kill -9 $pid) &
or to get the exit codes as well:
# Spawn a child process:
(dosmth) & pid=$!
# in the background, sleep for 10 secs then kill that process
(sleep 10 && kill -9 $pid) & waiter=$!
# wait on our worker process and return the exitcode
exitcode=$(wait $pid && echo $?)
# kill the waiter subshell, if it still runs
kill -9 $waiter 2>/dev/null
# 0 if we killed the waiter, cause that means the process finished before the waiter
finished_gracefully=$?
sleep 999&
t=$!
sleep 10
kill $t
I also had this question and found two more things very useful:
The SECONDS variable in bash.
The command "pgrep".
So I use something like this on the command line (OSX 10.9):
ping www.goooooogle.com & PING_PID=$(pgrep 'ping'); SECONDS=0; while pgrep -q 'ping'; do sleep 0.2; if [ $SECONDS = 10 ]; then kill $PING_PID; fi; done
As this is a loop I included a "sleep 0.2" to keep the CPU cool. ;-)
(BTW: ping is a bad example anyway, you just would use the built-in "-t" (timeout) option.)
Assuming you have (or can easily make) a pid file for tracking the child's pid, you could then create a script that checks the modtime of the pid file and kills/respawns the process as needed. Then just put the script in crontab to run at approximately the period you need.
Let me know if you need more details. If that doesn't sound like it'd suit your needs, what about upstart?
One way is to run the program in a subshell, and communicate with the subshell through a named pipe with the read command. This way you can check the exit status of the process being run and communicate this back through the pipe.
Here's an example of timing out the yes command after 3 seconds. It gets the PID of the process using pgrep (possibly only works on Linux). There is also some problem with using a pipe in that a process opening a pipe for read will hang until it is also opened for write, and vice versa. So to prevent the read command hanging, I've "wedged" open the pipe for read with a background subshell. (Another way to prevent a freeze to open the pipe read-write, i.e. read -t 5 <>finished.pipe - however, that also may not work except with Linux.)
rm -f finished.pipe
mkfifo finished.pipe
{ yes >/dev/null; echo finished >finished.pipe ; } &
SUBSHELL=$!
# Get command PID
while : ; do
PID=$( pgrep -P $SUBSHELL yes )
test "$PID" = "" || break
sleep 1
done
# Open pipe for writing
{ exec 4>finished.pipe ; while : ; do sleep 1000; done } &
read -t 3 FINISHED <finished.pipe
if [ "$FINISHED" = finished ] ; then
echo 'Subprocess finished'
else
echo 'Subprocess timed out'
kill $PID
fi
rm finished.pipe
Here's an attempt which tries to avoid killing a process after it has already exited, which reduces the chance of killing another process with the same process ID (although it's probably impossible to avoid this kind of error completely).
run_with_timeout ()
{
t=$1
shift
echo "running \"$*\" with timeout $t"
(
# first, run process in background
(exec sh -c "$*") &
pid=$!
echo $pid
# the timeout shell
(sleep $t ; echo timeout) &
waiter=$!
echo $waiter
# finally, allow process to end naturally
wait $pid
echo $?
) \
| (read pid
read waiter
if test $waiter != timeout ; then
read status
else
status=timeout
fi
# if we timed out, kill the process
if test $status = timeout ; then
kill $pid
exit 99
else
# if the program exited normally, kill the waiting shell
kill $waiter
exit $status
fi
)
}
Use like run_with_timeout 3 sleep 10000, which runs sleep 10000 but ends it after 3 seconds.
This is like other answers which use a background timeout process to kill the child process after a delay. I think this is almost the same as Dan's extended answer (https://stackoverflow.com/a/5161274/1351983), except the timeout shell will not be killed if it has already ended.
After this program has ended, there will still be a few lingering "sleep" processes running, but they should be harmless.
This may be a better solution than my other answer because it does not use the non-portable shell feature read -t and does not use pgrep.
Here's the third answer I've submitted here. This one handles signal interrupts and cleans up background processes when SIGINT is received. It uses the $BASHPID and exec trick used in the top answer to get the PID of a process (in this case $$ in a sh invocation). It uses a FIFO to communicate with a subshell that is responsible for killing and cleanup. (This is like the pipe in my second answer, but having a named pipe means that the signal handler can write into it too.)
run_with_timeout ()
{
t=$1 ; shift
trap cleanup 2
F=$$.fifo ; rm -f $F ; mkfifo $F
# first, run main process in background
"$#" & pid=$!
# sleeper process to time out
( sh -c "echo \$\$ >$F ; exec sleep $t" ; echo timeout >$F ) &
read sleeper <$F
# control shell. read from fifo.
# final input is "finished". after that
# we clean up. we can get a timeout or a
# signal first.
( exec 0<$F
while : ; do
read input
case $input in
finished)
test $sleeper != 0 && kill $sleeper
rm -f $F
exit 0
;;
timeout)
test $pid != 0 && kill $pid
sleeper=0
;;
signal)
test $pid != 0 && kill $pid
;;
esac
done
) &
# wait for process to end
wait $pid
status=$?
echo finished >$F
return $status
}
cleanup ()
{
echo signal >$$.fifo
}
I've tried to avoid race conditions as far as I can. However, one source of error I couldn't remove is when the process ends near the same time as the timeout. For example, run_with_timeout 2 sleep 2 or run_with_timeout 0 sleep 0. For me, the latter gives an error:
timeout.sh: line 250: kill: (23248) - No such process
as it is trying to kill a process that has already exited by itself.
#Kill command after 10 seconds
timeout 10 command
#If you don't have timeout installed, this is almost the same:
sh -c '(sleep 10; kill "$$") & command'
#The same as above, with muted duplicate messages:
sh -c '(sleep 10; kill "$$" 2>/dev/null) & command'