CODEWITHSUNDEEP
arraysstringbashshell
makansij
makansij

Reputation: 9885

Difference between arrays with " " and () in bash script?

I have two examples of a bash script. All I do is just use sed to replace some strings in a file. The file is specified when the script is run. So, you would run it like ./replace_file.sh input_file.

hug="g h 7"

for elm in $hug
do
  echo "replacing $elm"
  sed -i'_backup' "s/$elm/BOO/g" $1
done

and 

hug=('g' 'h' '7')

for elm in $hug
do
  echo "replacing $elm"
  sed -i'_backup' "s/$elm/BOO/g" $1
done

The first script above, echos the following:

replacing g
replacing h
replacing 7

But, the second one stops after replace g. It is unclear to me why. Can someone please shed some light?

Thank you.

Upvotes: 0

Views: 98

Answers (1)

David C. Rankin
David C. Rankin

Reputation: 84642

As set forth in the comment, when you attempt to iterate over the elements in the array by calling for elm in $hug, you are simply referencing the first element in the array. To iterate over the elements in the array, you use the array syntax, e.g. ${array[@]} to access each element sequentially (and you can quote the array to preserve whitespace in the elements.) In your case you need only:

#!/bin/bash

hug=('g' 'h' '7')

for elm in ${hug[@]}
do
echo "replacing $elm"
# sed -i'_backup' "s/$elm/BOO/g" $1
done

Output

$ bash arrayiter.sh
replacing g
replacing h
replacing 7

Upvotes: 2

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