bash script run to send process to background - linux

Question

Hi Im making a script to do some rsync process, for the rsync process, Sys admin has created the script, when it run it is asking select options, so i want to create a script to pass that argument from script and run it from cron.
list of directories to rsync take from file.
filelist=$(cat filelist.txt)
for i in filelist;do
echo -e "3\nY" | ./rsync.sh $i
#This will create a rsync log file
so i check the some value of log file and if it is empty i moving to the second file. if the file is not empty, i have to start rsync process as below that will take more that 2 hours.
if [ a != 0 ];then
echo -e "3\nN" | ./rsync.sh $i
above rsync process need to send to the background and take next file to loop. i check with the screen command, but screen is not working with server. also i need to get the duration that take to run process and passing to the log, when i use the time command i am unable to pass the echo variable. Also need to send this to background and take next file. appreciate any suggestions to success this task.
Question
1. How to send argument with Time command
echo -e "3\nY" | time ./rsync.sh $i
above one not working
how to send this to background and take next file to rsync while running previous rsync process.
Full Code
#!/bin/bash
filelist=$(cat filelist.txt)
Lpath=/opt/sas/sas_control/scripts/Logs/rsync_logs
date=$(date +"%m-%d-%Y")
timelog="time_result/rsync_time.log-$date"
for i in $filelist;do
#echo $i
b_i=$(basename $i)
echo $b_i
echo -e "3\nY" | ./rsync.sh $i
f=$(cat $Lpath/$(ls -tr $Lpath| grep rsync-dry-run-$b_i | tail -1) | grep 'transferred:' | cut -d':' -f2)
echo $f
if [ $f != 0 ]; then
#date=$(date +"%D : %r")
start_time=`date +%s`
echo "$b_i-start:$start_time" >> $timelog
#time ./rsync.sh $i < echo -e "3\nY" 2> "./time_result/$b_i-$date" &
time { echo -e "3\nY" | ./rsync.sh $i; } 2> "./time_result/$b_i-$date"
end_time=`date +%s`
s_time=$(cat $timelog|grep "$b_i-start" |cut -d ':' -f2)
duration=$(($end_time-$s_time))
echo "$b_i duration:$duration" >> $timelog
fi
done

Answer 1

Your question is not very clear, but I'll try:
(1) If I understand you correctly, you want to time the rsync.
My first attempt would be to use echo xxxx | time rsycnc. On my bash, this was however broken (or not supposed to work?). I'm normally using Zsh instead of bash, and on zsht, this indeed runs fine.
If it is important for you to use bash, an alternative (since the time for the echo can likely be neglected) would be to time the whole pipe, i.e. time (echo xxxx | time rsync), or even simpler time rsync <(echo xxxx)
(2) To send a process to the background, add an & to the line. However, the time command produces of course output (that's it purpose), and you don't want to receive output from a program in background. The solution is to redirect the output:
(time rsync <(echo xxxx) >output.txt 2>error.txt) &

Answer 2

If you want to time something, you can use:
time sleep 3
If you want to time two things, you can do a compound statement like this (note semicolon after second sleep):
time { sleep 3; sleep 4; }
So, you can do this to time your echo (which will take no time at all) and your rsync:
time { echo "something" | rsync something ; }
If you want to do that in the background:
time { echo "something" | rsync something ; } &
Full Code
#!/bin/bash
filelist=$(cat filelist.txt)
Lpath=/opt/sas/sas_control/scripts/Logs/rsync_logs
date=$(date +"%m-%d-%Y")
timelog="time_result/rsync_time.log-$date"
for i in $filelist;do
#echo $i
b_i=$(basename $i)
echo $b_i
echo -e "3\nY" | ./rsync.sh $i
f=$(cat $Lpath/$(ls -tr $Lpath| grep rsync-dry-run-$b_i | tail -1) | grep 'transferred:' | cut -d':' -f2)
echo $f
if [ $f != 0 ]; then
#date=$(date +"%D : %r")
start_time=`date +%s`
echo "$b_i-start:$start_time" >> $timelog
#time ./rsync.sh $i < echo -e "3\nY" 2> "./time_result/$b_i-$date" &
time { echo -e "3\nY" | ./rsync.sh $i; } 2> "./time_result/$b_i-$date"
end_time=`date +%s`
s_time=$(cat $timelog|grep "$b_i-start" |cut -d ':' -f2)
duration=$(($end_time-$s_time))
echo "$b_i duration:$duration" >> $timelog
fi
done