I am trying to take output of an command into array and for this tried following:
#!/bin/sh
cmd=($(date +%s;sleep 5; date +%s))
start_time=$cmd[0]
end_time=$cmd[1]
echo $start_time
#EOF
I was expection echo $start_time to give me start time but it print the following:
1572443382 1572443386[0]
Can't switch to bash shell and have only access to sh
Plain sh has no arrays. You have to cope without arrays. In your case that's easy:
start=$(date +%s)
sleep 5
end=$(date +%s)
echo "start=$start end=$end"
If you really, really want to have everything in one subshell then you have to store the output as a plain string and parse that string to retrieve the individual values. You can think of that one string as an "array" where each line is an array entry. Individual lines can be retrieved using sed (which uses indices starting from 1 instead of 0).
times=$(date +%s; sleep 5; date +%s)
echo "start=$(echo "$times" | sed -n 1p) end=$(echo "$times" | sed -n 2p)"
To store individual lines in variables use subshells:
times=$(date +%s; sleep 5; date +%s)
start=$(echo "$times" | sed -n 1p)
end=$(echo "$times" | sed -n 2p)
echo "start=$start end=$end"
However, if you just want to compute how long sleep 5 took you might as well use time sleep 5 which already does that for you.
The positional parameters are the closest thing sh has to an array:
sh-3.2$ set -- "$(date +%s)"; sleep 5; set -- "$@" "$(date +%s)"
sh-3.2$ start=$1 end=$2; echo "$start -> $end"
1572448562 -> 1572448567
set -- $(date +%s; sleep 5; date +%s); echo "$1 -> $2". Your solution can even be used without mangling the original positional parameters: set -- $(...) "$@"; ...; shift 2 # everything is back to normal.You need to use ${array[index]} syntax to access array elements. So, change your start_time and end_time to as follows.
start_time=${cmd[0]}
end_time=${cmd[1]}
Also change
#!/bin/sh
to
#!/bin/bash
