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bashshellquoting

Quoting in sh bash ... ("") ($'') ('')

I hopefully would like to say I understand quotings used in BASH and their difference , " ", ' ', $' '.

I saw many shell scripts containing

IFS=$'\n'

but NO 

IFS="\n"

It looks at least to me that there is no difference. and in my environment both work correctly (for my understanding), What difference is here? Is it just a custom?

Solution

  • They aren't the same.

    IFS=$'\n' sets the value of IFS to a literal newline.

    IFS="\n" sets the value of IFS to the string \n.

    See?

    $ IFS=$'\n'
$ declare -p IFS
declare -- IFS="
"
$ IFS="\n"
$ declare -p IFS
declare -- IFS="\\n"

$ IFS="\n" read a b c <<<$'anbncndn'
$ declare -p a b c
declare -- a="a"
declare -- b="b"
declare -- c="cndn"
$ IFS=$'\n' read a b c <<<$'anbncndn'
$ declare -p a b c
declare -- a="anbncndn"
declare -- b=""
declare -- c=""