CODEWITHSUNDEEP
arraysbashunixsh
Mathews Jose
Mathews Jose

Reputation: 409

Bash : Can Here Strings <<< work with multiple variables as input?

I am trying to initialize an array with multiple variables as below .

StringOne="This is a Test String"
StringTwo="This is a New String"
read -r -a Values <<< "$StringOne" "$StringTwo"

But It seems like array is getting values from only the first variable .ie StringOne

 $ echo ${Values[0]}
 This
 $ echo ${Values[1]}
 is
 $ echo ${Values[2]}
 a
 $ echo ${Values[3]}
 Test
 ${Values[4]}
 String
 $ echo ${Values[5]}

 $ echo ${Values[6]}

 $

What is wrong with this way of passing variable value for array initialization ? Cant we pass multiple variables with <<< operator ?

Upvotes: 1

Views: 785

Answers (2)

user2350426
user2350426

Reputation:

Use:

read -r -a Values <<< "$StringOne"" ""$StringTwo"

Or:

read -r -a Values <<< "$StringOne"' '"$StringTwo"

Or:

out="$StringOne $StringTwo"
read -r -a Values <<< "$out"

Or some other variation on this theme.

This works because the string sent via <<< is the result of the expansion of what in on the right of it. We can make both variables act as one long string by concatenating them.

Upvotes: 0

John Bollinger
John Bollinger

Reputation: 180286

What is wrong with this way of passing variable value for array initialization ? Cant we pass multiple variables with <<< operator ?

Yes and no. The <<< operator takes one shell word as its operand, as is presented pretty clearly in its documentation. But you can combine the values of multiple variables in a single shell word by appropriate use of quoting:

StringOne="This is a Test String"
StringTwo="This is a New String"
read -r -a Values <<< "$StringOne $StringTwo"
echo "${Values[@]}"

Output:

This is a Test String This is a New String

Upvotes: 2

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