Shell Programming and Scripting

In File A I have 1st col as numbers. Using these numbers, I need to find out
the rows at this numbered index in other file.

I know loose commands.
To get the 1st col from file A :
awk '{print $1}' fileA

To get the row at the index, say 100 - from file B :
sed '100p' fileB

After executing 1st command, I get all values in one go, & I cannot use these values
one by one. Can anyone guide on this, regarding how to solve this?

Assume that the files are named fileA and fileB. You can write the commands as:

Code:

awk '{print $1}' fileA | while read indx; do
sed '${indx}p' fileB
done

Just try if this works. I am just a bit doubtful about the ${indx} inside the sed command.

Hope this helps!

Cheers!

Code:

awk '{print $1}' fileA | while read indx; do
sed "\${indx}p" fileB
done

Either sed '${indx}p' or sed '/${indx}p'

is not working as expected. Can anyone please suggest how we can assign variable with this command?

Try:
sed "${indx}p" fileB

Note the double quotes. Double quote is the character above single quote on your keyboard.

read more closely the suggestion.

Notice the backslash in front of the dollar sign which is quoting the dollar sign and preventing the indx variable from being referenced.