Bash Printf Argument $1 vs "$1"

Asked Aug 21 '20 at 23:04

Active Aug 21 '20 at 23:15

Viewed 19 times

I have a shell script that prints the first argument passed to it in the command line. I was experimenting with $1 and "$1". Interestingly to me, when I pass "John Doe" I get different outputs.

hw Version1

#!/bin/bash
printf "Hello %s\n" $1

Result is the following. Seems like it loops through strings separated by space:

$ hw "John Doe"
Hello John
Hello Doe

hw Version2

#!/bin/bash
printf "Hello %s\n" "$1"

Result is:

$ hw "John Doe"
Hello John Doe

what is the difference between $1 and "$1" when the argument in the command line is something like "string1 string2 ... stringn"?

edited Aug 21 '20 at 23:15

asked Aug 21 '20 at 23:04

shashashamti2008

1

Related: When is double-quoting necessary? – steeldriver Aug 21 '20 at 23:15
1

It's a duplicate all right but the question is well framed and formatted. IMO doesn't deserve a downvote – iruvar Aug 21 '20 at 23:24
Thank you. I was surprised when it was downvoted. – shashashamti2008 Aug 22 '20 at 00:38
1

What is not covered elsewhere is why Hello appears twice in Version 1. This is a specific action by the printf built-in: "The format is reused as necessary to consume all of the arguments." – Paul_Pedant Aug 22 '20 at 10:39

Bash Printf Argument $1 vs "$1"

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