$a=`time` real 0m0.000s user 0m0.000s sys 0m0.000s $a bash: a: command not found $a=`ls` $a bash: a: command not found $echo a a $echo $a a.txt b.txt trueangle $echo `a` bash: a: command not found $a=`ls` $b=time $echo $b time $b=`time` real 0m0.000s user 0m0.000s sys 0m0.000s $echo $b $b=`time` real 0m0.000s user 0m0.000s sys 0m0.000s $echo $b $b=date $echo $b date $b=`date` $echo $b Fri Apr 22 22:50:27 IST 2016 $ http://mywiki.wooledge.org/BashFAQ/032