script is as below

v_process_run=5
typeset -i p_cnt=0
pdata=/home/proc_data.log

while [ $p_cnt -le $v_process_run ]
do
# execute script in background

dummy_test.sh "a1" "a2" &
p_cnt=$p_cnt+1

echo "data : $p_cnt : Y" >> $pdata

done



file created with following data in /home/proc_data.log
data : 1 : Y
data : 2 : Y
data : 3 : Y
data : 4 : Y
data : 5 : Y

now when each background process is completed
want to delete the line for matching pattern from log file without redirecting to new file ( below command is not working , please suggest)

for example :
grep "data : 3 : Y" /home/proc_data.log | sed "/data : 3 : Y/d"

or

now when each background process is completed
want to update the line for that process from log file
without redirecting to new file ( please suggest);

search for : data : 3 : Y
and relace with : data : 3 : N

hence output in the file should be

data : 1 : Y
data : 2 : Y
data : 3 : N
data : 4 : Y
data : 5 : Y

One way is to use ed(1). Here is a sample script to replace line 3 of your sample file with "hello there"
Invoke script as follows