loop over output of command and print both index and value

Question

I have checked Looping over arrays, printing both index and value. The issue is I want to loop over output of command and not an array.

The code i came up with is:

array=($(seq 1 10))

for i in "${!array[@]}"; do
  printf "%s\t%s\n" "$i" "${array[$i]}"
done

or,

ITER=0
for I in $(seq 1 10)
do  
    echo ${I} ${ITER}
    ITER=$(expr $ITER + 1)
done

What i want to know is, is it possible to do it within the loop only (without array or ITER) outside the loop?

What i am looking for is something like:

for index,value in $(seq 1 10); do
  echo $index $value
done

If you need a running index, you have to calculate it manually. Also, it is unclear what exactly you mean by _loop over output_. From the code snippets you posted, I infer that you mean to _loop over the individual words which a command writes to standard output_, but it's better to state this precisely when asking such a question. — user1934428, Aug 19 '22 at 06:08
This is what you already said. But the words "loop over output" does not have a real meaning. Should each iteration of the loop consume one character of the output, or one word of the output, or whatever? In your example, you are looping over the words in stdout of the command, and if this is really what you want to achieve in the general case, you better state this explicitly. — user1934428, Aug 19 '22 at 06:22
Neither the code you posted nor the text in your question says this. Furthermore, if you google for this problem, you will find many suggestions, so it's not clear to me at which point you are stuck. — user1934428, Aug 19 '22 at 06:48

score 0 · Accepted Answer · answered Aug 19 '22 at 07:20

0

Let us know your actual requirement:

01)
#!/bin/bash
index=0
for filename in $(ls -atr)
do
        indx=$(($indx+1))
        echo "Index: $indx $filename"
done

output:

$  ./73412398.sh
Index: 1 ..
Index: 2 73412398.sh
Index: 3 .

One more try:

for index in $(ls -atr | grep -n $)
do
 echo $index | sed "s/\([0-9]*\):/\1 /;"
done

output:

1 ..
2 73412398.sh
3 .

answered Aug 19 '22 at 07:20

murugesan openssl

After fixing your first answer it worked. There are many typos in the first one. Probably you pasted the wrong thing. The second one is what i needed. – Ahmad Ismail Aug 19 '22 at 07:24
I posted a response after taking hint from your answer. – Ahmad Ismail Aug 19 '22 at 07:40

score 0 · Answer 2 · answered Aug 19 '22 at 07:39

0

after modifying murugesan openssl's answer, the solution for me is:

for indexval in $(ls -atr | grep -n $)
do
 echo index is "${indexval%%:*}"
 echo value is "${indexval#*:}"
done

answered Aug 19 '22 at 07:39

Ahmad Ismail

2 Answers2