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I am trying to use a newline in bash. I found that I need ANSI C quoting for that (i.e. $'\n'), but this often does not work for me. So I am wondering what I am doing wrong.

# This works
>> echo $'a\nb\nc'
a
b
c

# This doesn't 
>> A=$'a\nb\nc'
>> echo $A
a b c 

# Also, this does not work
>> A="a b c"
>> echo ${A// /$'\n'}
a b c 

If I use tab instead of newline, I have the same problems. Other ANSI C quoting work like \', or \", or even \b.

GNU Bash; version: 4.3.11(1)

1

Because you've not quoted the variable in:

echo $A

it is subject to splitting and globbing. The first step is the expansion of the variable's contents:

echo a $'\n' b $'\n' c -- where the $'\n' bits represent actual newlines.

Then, the various pieces are split on $IFS, resulting in:

echo a b c

Then, since there are no wildcards to generate additional filenames, the strings are passed on to echo.

When you quote the variable, with echo "$A", you inhibit splitting and globbing.

See the change yourself if you modify IFS:

oIFS=$IFS
IFS=
echo $A
IFS=$oIFS

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