How to get all the elements to show in a for loop in bash-CodePudding

The problem is that when I execute this command

#!/bin/bash
for i in "${@:2}";
do 
uniqueletters=$(echo $i | awk -v RS= '{$1=$1}1' | sed 's/ //g')
done
echo $uniqueletters

On this

7216859340 FRENCH ARABIC CHINESE

I only get CHINESE and both of these commands don't seem to execute

awk -v RS= '{$1=$1}1' | sed 's/ //g'

But my desired output is this please

FRENCHARABICCHINESE

CodePudding user response：

Putting awk (or sed) inside a shell loop is inefficient and considered an anti-pattern in most cases. You can accomplish what you're trying to do in a much simpler and more efficient way without using a loop and an external command:

#!/bin/bash

printf -v uniqueletters '%s' "${@:2}"
echo "$uniqueletters"

This uses printf's implicit loop and the -v option, which causes the output to be assigned to the variable uniqueletters rather than being printed to the standard output.
Note: the variable name uniqueletters doesn't make sense to me.

CodePudding user response：

Seems like you are always overwriting the value of the variable uniqueletters in the loop. What this means is that, uniqueletters will only contain the last letter after coming out of the loop.

The following is a simple fix for your code

    #!/bin/bash
    uniqueletters=""
    for i in "${@:2}"; do
        uniqueletters =$(echo $i | awk -v RS= '{$1=$1}1')
    done
    echo $uniqueletters