Add seconds to current time in Bash [duplicate] - bash

Question

This question already has answers here:
Bash script/command to print out date 5 min before/after
(4 answers)
Closed 5 years ago.
I want to add 10 seconds 10 times. But I don't know well how to add times to the value.
This is my code.
./time.sh
time=$(date)
counter=1
while [ $counter -le 10 ]
do
echo "$time"
time=$('$time + 10 seconds') //error occurred.
((counter++))
done
echo All done

Answer 1

Using GNU Date
Assuming GNU date, replace:
time=$('$time + 10 seconds')
with:
time=$(date -d "$time + 10 seconds")
Putting it all together, try:
$ cat a.sh
t=$(date)
counter=1
while [ "$counter" -le 10 ]
do
echo "$t"
t=$(date -d "$t + 10 seconds")
((counter++))
done
echo All done
(I renamed time to t because time is also a bash built-in command and it is best to avoid potential confusion.)
When run, the output looks like:
$ bash a.sh
Tue Jan 16 19:19:44 PST 2018
Tue Jan 16 19:19:54 PST 2018
Tue Jan 16 19:20:04 PST 2018
Tue Jan 16 19:20:14 PST 2018
Tue Jan 16 19:20:24 PST 2018
Tue Jan 16 19:20:34 PST 2018
Tue Jan 16 19:20:44 PST 2018
Tue Jan 16 19:20:54 PST 2018
Tue Jan 16 19:21:04 PST 2018
Tue Jan 16 19:21:14 PST 2018
All done
Using Bash (>4.2)
Recent versions of bash support date calculations without external utilities. Try:
$ cat b.sh
#!/bin/bash
printf -v t '%(%s)T' -1
counter=1
while [ "$counter" -le 10 ]
do
((t=t+10))
printf '%(%c)T\n' "$t"
((counter++))
done
echo All done
Here, t is time since epoch in seconds.
When run, the output looks like:
$ bash b.sh
Tue 16 Jan 2018 07:31:44 PM PST
Tue 16 Jan 2018 07:31:54 PM PST
Tue 16 Jan 2018 07:32:04 PM PST
Tue 16 Jan 2018 07:32:14 PM PST
Tue 16 Jan 2018 07:32:24 PM PST
Tue 16 Jan 2018 07:32:34 PM PST
Tue 16 Jan 2018 07:32:44 PM PST
Tue 16 Jan 2018 07:32:54 PM PST
Tue 16 Jan 2018 07:33:04 PM PST
Tue 16 Jan 2018 07:33:14 PM PST
All done