mjhjmtu

update attempt to clarify more, using an example, does the following shell commands:

SHELLVARIABLE="1st line,
2nd line,
3rd line,
" 
printf '%s' "$SHELLVARIABLE"

generate this output:

1st line,<newline>2nd line,<newline>3rd line,<newline>

<newline> being the character 0x0a / n?

Original question formulation

What is the correct (POSIX-confirm) way to store a newline character 0x0a (aka known by its commen c style escap n) into a shell variable.

I want to make sure that doing the following:

SHELLVARIABLE="
"

is, not merely working by chance but instead is indeed the correct way.

Since POSIX's printf is perfectly capable of producing a newline character (i.e. printf 'n', or printf '%b' '012') I first attempted a more explicit (? or correct?) form:

SHELLVARIABLE="$(printf 'n')"

though a tempting approach, does not work. As the according to the standard, command substitution (i.e. via $() and ` `) shall remove

sequences of one or more newlines at the end of the substitution.

Note: Asking to store a single trailing newline into a shell variable is only to abstract the more general use case (i indeed seek answer to) that is how to store a string into POSIX shell variable which ends with the newline character.

Using a hard newline in a quoted string is fine.

Though personally, I'd avoid it if you just want the newline: I find it looks odd and there's a slight risk of accidentally hitting extra spaces at the end of the first line (so you'd get e.g. <space><newline>). But that's just me.

Command substitution indeed strips trailing newlines, but only those. The workaround is to make sure that the final character is something other than a newline and then strip that character off.

Both of these should give you a newline:

nl1='
'

nl2="$(printf 'nx')"
nl2="$nl2%x"