func () {
local arrayOfParams=$#
local CMD="ps aux | grep -v grep"
for item in ${arrayOfParams[#]};
do
local CMD="$CMD | grep -e $item"
done
echo "Current process PID : $$"
echo "`date`: CMD is -> $CMD"
local isProcRunning=`eval ${CMD}`
if [[ 0 -eq `echo "$isProcRunning" | wc -l` ]];
then
echo "`date`: Following process is running: "
echo "$isProcRunning"
echo ""
if [[ "$FORCE_RUN" == true ]];
then
echo "`date`: User forced the run of current process ..."
# we extract the PIDs of proces mathcing our search criteria
PIDS=(`echo $isProcRunning | awk '{print \$2}'`)
for PID in "${PIDS[#]}";
do
# we extract the command running on said PID so that we know what we kill
local PIDCMD=`ps -o cmd -p ${PID} --no-headers`
echo "`date`: Killing PID: $PID with CMD -> $PIDCMD"
kill -9 $PID
done
else
echo "`date`: Current process will exit!!!"
fi
exit 0
fi
}
The above code is meant to check if current process is already running .
I use ps -ef and grep based on some params which should be found under CMD
I remove the line coresponding to the current PID and then I expect the wc -l to return 0, but it's returning 1.
I run that line outside of the script and I get 0 indeed.
Any idea why this is happening ?
I keep getting zero status even after interrupting the script.
The first script
#!/bin/bash
## call the backup script
/usr/local/bin/backup 2>&1 >/dev/null
echo $?
backup
#!/bin/bash
exitscript() {
rm -f $LOCKFILE
echo "Script Status: $1 | tee -a ${LOG}"
echo "> End Date: $(date +'%d.%m.%Y %H:%M:%S')" | tee -a ${LOG}
exit $1
}
######START#######
trap "exitscript 1" 1 2 23 24 25
rsync ${args} ${src} ${dest} | tee -a ${RSYNC_LOG}
retcode=${PIPESTATUS[0]}
if [[ ${retcode} -ne 0 ]]; then
exitcode=1
fi
exitscript ${exitcode:-0}
When the First Script is run, it returns exit status of 0 although i have tried to kill the backup script before it ends (for that i have created a very large size file so that rsync takes time to copy the file and i get the time to kill the script before it ends)
ps -ef | grep -i backup
kill $PID
Another thing is that even after killing the backup script, rsync still runs. I would like for rsync to stop once the script is being killed and my first script to return the status code of zero.
Much appreciation for any suggestions. Thanks!
I assume the missing quote in echo "Script Status: $1 | tee -a ${LOG} is not relevant to the question.
When you want a function to handle the trap, you need to export that function.
And when you want to kill children, you should add these in your trap-function.
I tested these adjustments with a sleep command, it should work for rsync too.
#!/bin/bash
exitscript() {
echo "Script Status: $1"
(( $pleasekill > 0 )) && kill ${pleasekill}
echo "> End Date: $(date +'%d.%m.%Y %H:%M:%S')"
exit $1
}
# Export the function exitscript
export exitscript
######START#######
pleasekill=0
trap "exitscript 1" 1 2 23 24 25
# Start I/O-friendly rsync function
sleep 30 &
pleasekill=$!
wait
exitscript 2
When you test this with the first script, use ^C or kill -1 pid_of_backup.
I am newbie to shell. I am trying to run 3 jobs sequentially. But I am not sure where I am going wrong. The jobs are not running in sequence. Please help on this.
Job 1
Job 2
Job 3
Here is the script to run the jobs:
#!/bin/bash
{
sync;
echo 3 > /proc/sys/vm/drop_caches
/data/Job1.sh
if [ `ps -ef | egrep 'awk' | egrep -v egrep | wc -l` -gt 1 ]]
/data/Job2.sh
if [[ `ps -ef | egrep 'awk' | egrep -v egrep | wc -l` -gt 1 ]];
/data/Job3.sh
fi
}
UPDATE:
#!/bin/sh
if [ $1 ]; then
NUM_PROC=$1
else
NUM_PROC=10
fi
for i in `seq 0 $((NUM_PROC-1))`; do
awk 'BEGIN {for(i=0;i<10000;i++)for(j=0;j<10000;j++);}' &
done
echo "PIDS: `pidof awk`"
**Shell script running: **scripts/job.sh 5****
You can make use of wait if you want to use it as a child process. Otherwise, remove the & after $job and the entire line wait $! as commented in the example.
#! /bin/bash
JOB_ARRAY=("/data/Job1.sh" "/data/Job2.sh" "/data/Job3.sh")
for job in "${JOB_ARRAY[#]}"; do
sync;
echo 3 > /proc/sys/vm/drop_caches;
echo "Starting job $job"
$job & # remove `&`
echo "Started job with pid $!"
wait $! # remove entire line
echo "Job finished, exit code is $?"
done
exit 0
EDIT:
In the JobX.sh scripts you'll have to wait until the child processes are finished. Append the following code to each JobX.sh script:
NUM_PROC=$1
[ ! -z "${NUM_PROC}" ] || NUM_PROC=10
for i in `seq 0 $((NUM_PROC-1))`; do
awk 'BEGIN {for(i=0;i<10000;i++)for(j=0;j<10000;j++);}' &
done
echo "PIDS: `pidof awk`"
# Wait for every child process to finish
wait
exit $?
p.s. you should always end your scripts with exit. Always enclose variables with "" if you use it in if, while, fir (etc) statements. And try to make functions instead of separate scripts:
#! /bin/bash
function _test_echo {
local message=$1
echo $message
}
_test_echo "Hello world!"
exit 0
Good luck scripting!
I have a process I start on my shell that prints out data and I have a python script that calculates it and should return that to the process. How can I do that?
I know using pipe or > could help me with one side, but how can I achieve a two-way redirection?
Is something like: my_process | my_script | my_process legal?
What I want to happen:
start process from shell
process sends data to my script (instead of printing it to STDOUT)
my script returns an answer to process (instead of printing it to
STDOUT)
return to step 2
It's emulatable with FIFOs (or if you're using python, you can create your own pipes with the pipe system call and redirect them according to your arrangement).
Some example code:
#!/bin/sh
#note: the resource management and error handling here is not very clean or robust
mkfifo fifo0 fifo1
exec 3<>fifo0
exec 4<>fifo1
rm -f fifo0 fifo1
many()
{
i=0
while [ $i -lt $1 ]; do
echo -n x
i=$((i+1))
done
echo
}
proc1()
{
ulimit_p=$(ulimit -p)
while :; do
echo proc1_msg
echo >&2 proc1_written=proc1_msg
read var
echo >&2 proc1_read=$var
sleep 1
done
}
proc2()
{
while :; do
read var
echo >&2 proc2_read=$var
echo proc2_msg
echo >&2 proc2_written=proc2_msg
done
}
pid=0
trap 'echo kill $pid; kill $pid; exit 130' INT
proc1 <&3 >&4 & pid=$!
proc2 <&4 >&3
I am a shell scripting newbie trying to understand some code, but there are some lines that are too complexe for me. The piece of code I'm talking about can be found here: https://gist.github.com/447191
It's purpose is to start, stop and restart a server. That's pretty standard stuff, so it's worth taking some time to understand it. I commented those lines where I am unsure about the meaning or that I completely don't understand, hoping that somone could give me some explanation.
#!/bin/bash
#
BASE=/tmp
PID=$BASE/app.pid
LOG=$BASE/app.log
ERROR=$BASE/app-error.log
PORT=11211
LISTEN_IP='0.0.0.0'
MEM_SIZE=4
CMD='memcached'
# Does this mean, that the COMMAND variable can adopt different values, depending on
# what is entered as parameter? "memcached" is chosen by default, port, ip address and
# memory size are options, but what is -v?
COMMAND="$CMD -p $PORT -l $LISTEN_IP -m $MEM_SIZE -v"
USR=user
status() {
echo
echo "==== Status"
if [ -f $PID ]
then
echo
echo "Pid file: $( cat $PID ) [$PID]"
echo
# ps -ef: Display uid, pid, parent pid, recent CPU usage, process start time,
# controling tty, elapsed CPU usage, and the associated command of all other processes
# that are owned by other users.
# The rest of this line I don't understand, especially grep -v grep
ps -ef | grep -v grep | grep $( cat $PID )
else
echo
echo "No Pid file"
fi
}
start() {
if [ -f $PID ]
then
echo
echo "Already started. PID: [$( cat $PID )]"
else
echo "==== Start"
# Lock file that indicates that no 2nd instance should be started
touch $PID
# COMMAND is called as background process and ignores SIGHUP signal, writes it's
# output to the LOG file.
if nohup $COMMAND >>$LOG 2>&1 &
# The pid of the last background is saved in the PID file
then echo $! >$PID
echo "Done."
echo "$(date '+%Y-%m-%d %X'): START" >>$LOG
else echo "Error... "
/bin/rm $PID
fi
fi
}
# I don't understand this function :-(
kill_cmd() {
SIGNAL=""; MSG="Killing "
while true
do
LIST=`ps -ef | grep -v grep | grep $CMD | grep -w $USR | awk '{print $2}'`
if [ "$LIST" ]
then
echo; echo "$MSG $LIST" ; echo
echo $LIST | xargs kill $SIGNAL
# Why this sleep command?
sleep 2
SIGNAL="-9" ; MSG="Killing $SIGNAL"
if [ -f $PID ]
then
/bin/rm $PID
fi
else
echo; echo "All killed..." ; echo
break
fi
done
}
stop() {
echo "==== Stop"
if [ -f $PID ]
then
if kill $( cat $PID )
then echo "Done."
echo "$(date '+%Y-%m-%d %X'): STOP" >>$LOG
fi
/bin/rm $PID
kill_cmd
else
echo "No pid file. Already stopped?"
fi
}
case "$1" in
'start')
start
;;
'stop')
stop
;;
'restart')
stop ; echo "Sleeping..."; sleep 1 ;
start
;;
'status')
status
;;
*)
echo
echo "Usage: $0 { start | stop | restart | status }"
echo
exit 1
;;
esac
exit 0
1)
COMMAND="$CMD -p $PORT -l $LISTEN_IP -m $MEM_SIZE -v" — -v in Unix tradition very often is a shortcut for --verbose. All those dollar signs are variable expansion (their text values are inserted into the string assigned to new variable COMMAND).
2)
ps -ef | grep -v grep | grep $( cat $PID ) - it's a pipe: ps redirects its output to grep which outputs to another grep and the end result is printed to the standard output.
grep -v grep means "take all lines that do not contain 'grep'" (grep itself is a process, so you need to exclude it from output of ps). $( $command ) is a way to run command and insert its standard output into this place of script (in this case: cat $PID will show contents of file with name $PID).
3) kill_cmd.
This function is an endless loop trying to kill the LIST of 'memcached' processes' PIDs. First, it tries to send TERM signal (politely asking each process in $LIST to quit, saving its work and shutting down correctly), gives them 2 seconds (sleep 2) to do their shutdown job and then tries to make sure that all processes are killed using signal KILL (-9), which slays the process immediately using OS facilities: if a process has not done its shutdown work in 2 seconds, it's considered hung). If slaying with kill -9 was successful, it removes the PID file and quits the loop.
ps -ef | grep -v grep | grep $CMD | grep -w $USR | awk '{print $2}' prints all PIDs of processes with name $CMD ('memcached') and user $USR ('user'). -w option of grep means 'the Whole word only' (this excludes situations where the sought name is a part of another process name, like 'fakememcached'). awk is a little interpreter most often used to take a word number N from every line of input (you can consider it a selector for a column of a text table). In this case, it prints every second word in ps output lines, that means every PID.
If you have any other questions, I'll add answers below.
Here is an explanation of the pieces of code you do not understand:
1.
# Does this mean, that the COMMAND variable can adopt different values, depending on
# what is entered as parameter? "memcached" is chosen by default, port, ip address and
# memory size are options, but what is -v?
COMMAND="$CMD -p $PORT -l $LISTEN_IP -m $MEM_SIZE -v"
In the man, near -v:
$ man memcached
...
-v Be verbose during the event loop; print out errors and warnings.
...
2.
# ps -ef: Display uid, pid, parent pid, recent CPU usage, process start time,
# controling tty, elapsed CPU usage, and the associated command of all other processes
# that are owned by other users.
# The rest of this line I don't understand, especially grep -v grep
ps -ef | grep -v grep | grep $( cat $PID )
Print all processes details (ps -ef), exclude the line with grep (grep -v grep) (since you are running grep it will display itself in the process list) and filter by the text found in the file named $PID (/tmp/app.pid) (grep $( cat $PID )).
3.
# I don't understand this function :-(
kill_cmd() {
SIGNAL=""; MSG="Killing "
while true
do
## create a list with all the pid numbers filtered by command (memcached) and user ($USR)
LIST=`ps -ef | grep -v grep | grep $CMD | grep -w $USR | awk '{print $2}'`
## if $LIST is not empty... proceed
if [ "$LIST" ]
then
echo; echo "$MSG $LIST" ; echo
## kill all the processes in the $LIST (xargs will get the list from the pipe and put it at the end of the kill command; something like this < kill $SIGNAL $LIST > )
echo $LIST | xargs kill $SIGNAL
# Why this sleep command?
## some processes might take one or two seconds to perish
sleep 2
SIGNAL="-9" ; MSG="Killing $SIGNAL"
## if the file $PID still exists, delete it
if [ -f $PID ]
then
/bin/rm $PID
fi
## if list is empty
else
echo; echo "All killed..." ; echo
## get out of the while loop
break
fi
done
}
This function will kill all the processes related to memcached slowly and painfully (actually quite the opposite).
Above are the explanations.