how to end a loop when a command ends-CodePudding

I have this bash script:

#!/bin/bash

if [ "$#" -eq 4 ]
then
    rep_origine="$1"
    rep_dest="$2"
    temps_exec="$3"
    temps_refr="$4"
else 
    echo "Usage : $0 [files directory] [destination directory] [execution time$
    exit 2
fi


cp -R "$rep_origine" "$rep_dest" &
cp_process="$!"

while [ "$cp_process" -eq "$!" ]
do
    cp_process="$!"
    sleep "$temps_exec"; kill -STOP "$cp_process"
    sleep "$temps_refr"; kill -CONT "$cp_process"
done

I would like my loop to end when the cp command ends. Therefore, I put that when the last PID was not the same as the PID of cp, the loop should end but it does not work.

I don't see how to indicate that the loop should end when the cp command ends.

CodePudding user response：

I would use kill with the non-harming signal 0 to check if the process is still alive:

while kill -0 $cp_process 2>/dev/null
do
    # work indicator:
    echo -n '.'
    sleep 1
done

If the purpose is to temporarilly stop the process in the loop:

while kill -STOP $cp_process 2>/dev/null
do
    # do work while the process is stopped here

    kill -CONT $cp_process
    # give the process execution time:
    sleep $temps_exec
done

CodePudding user response：

Not asked for, but the brackets in your usage message symbolize optional parameters, while you check for strictly 4 arguments.

Linux has a timeout program, to stop a process, which does not finish in a given time - maybe that's something for you.

#!/bin/bash

if [ "$#" -eq 4 ]
then
    rep_origine="$1"
    rep_dest="$2"
    temps_exec="$3"
    temps_refr="$4"
else 
    echo "Usage : $0 source_dir destination_dir execution_time temps_refr
    exit 2
fi

timeout temps_exec cp -R "$rep_origine" "$rep_dest"

See man timeout for further details.

CodePudding user response：

You can simply use ps and grep in this scenario to check if the process is running or not,

Ex:

#!/bin/bash

if [ "$#" -eq 4 ]
then
    rep_origine="$1"
    rep_dest="$2"
    temps_exec="$3"
    temps_refr="$4"
else 
    echo "Usage : $0 [files directory] [destination directory] [execution time$ "
    exit 2
fi
cp -R "$rep_origine" "$rep_dest" &
cp_process="$!"

# check if the process is still running or not
while true; do
check=$(ps -ef | grep -w $cp_process | grep -v grep | wc -l)
  if [ $check -ge "1" ]; then
      echo "process $cp_process is still running"
  else
      echo "Process $cp_process has been completed"
      break
  fi
  sleep 1
done