SHELL SCRIPT

 

Use variables in a bash for loop 

One way is using eval:

for i in $( eval echo {0..$length} )
do
       echo "do something right $i"
done

Note what happens when you set length=;ls or length=; rm * (don't try the latter though).

safely, using seq:

for i in $( seq 0 $length )
do
       echo "do something right $i"
done

or you can use the c-style for loop, which is also safe:

for (( i = 0; i <= $length; i++ )) 
do 
       echo "do something right $i"
done

courtesy: https://stackoverflow.com/questions/17181787/how-to-use-variables-in-a-bash-for-loop




Decimal calculations

For decimal calculations, we can use bc command to get the output to a particular number of decimal places. bc (Bash Calculator) is a command line calculator that supports calculation up to a certain number of decimal points.

echo "scale=2;22/7" | bc

Where scale defines the number of decimal places required in the output.

Getting output to 2 decimal places

courtesy:https://www.freecodecamp.org/news/shell-scripting-crash-course-how-to-write-bash-scripts-in-linux/