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shellfish

How to capture newlines from command substitution output in fish shell?

In bash, newline characters are preserved through command substitution:

$ TEST="$(echo 'a
  b
  c
  ')" && echo "$TEST"
# →
a
b
c

However, when I try to do the same in fish shell, the newline characters get converted into spaces:

$ set TEST (echo "a
  b
  c
  "); and echo "$TEST"
# →
a b c

How to make fish save the newline characters as newlines?

Solution

  • Conceptually, they are not converted into spaces: you are getting a list!

    > echo -e "1\n2\n3" > foo
> cat foo
1
2
3
> set myFoo (cat foo)
> echo $myFoo
1 2 3
> echo $myFoo[0..2]
1 2

    Therefore we apply the machinery available for lists; for instance, joining with a separator (note the extra backspace to get rid of undesirable spaces):

    > echo {\b$myFoo}\n
1
2
3
 # extra newline here

    This is not ideal; string does it better:

    > string join \n $myFoo
1
2
3