How can I have a newline in a string in fish shell?

Question

Is same question as How can I have a newline in a string in sh? but in fish shell.

In bash we have:

$'this is line\nthis is another line'

who produces the expected result, but in fish this doesnt works.

fish has a similar way to do this?

Edit 1:

has the literal method wisely mentioned by the faho:

'this is line this is another line'

But i'm really curious about the existence of a method keeping reference for \n as line break like in shell.

I want to know if I can use this string "this is a line\nthis is another line" making sure that the fish will consider \n as a line break and not a literal.

Amusingly, the fish design doc [describes `$''` as "silly"](https://fishshell.com/docs/current/design.html#ortho) — glenn jackman, Jan 24 '20 at 13:26
Many Thank's Amusingly, now I understand the position of fish shell about this. — Iury Fukuda, Jan 26 '20 at 20:46

score 7 · Answer 1 · answered Jan 23 '20 at 20:53

7

Fish replaces \n outside of quotes with a newline, so you can stop and restart the quotes (note no "$" before the quotes):

'this is line'\n'this is another line'

Fish follows quotes across lines, so you can include a literal newline:

'this is line this is another line'

answered Jan 23 '20 at 20:53

faho

14,470
2
37
47

thanks for your time with this answer. i can use with this way in shell too. have another way to do this keeping '\n' like in shell? – Iury Fukuda Jan 24 '20 at 02:48
No, you can't do it this way in "shell". POSIX-like shells do not interpret `\n` outside of `$''` - `echo 'a'\n'b'` prints `anb`. – faho Jan 24 '20 at 16:27
There is also, in both fish and POSIX shells, `echo -e`, which will interpret backslash-escapes in strings, so `echo -e 'a\nb'` will also print a, a newline and b. I'd recommend just using the first way I gave you, as that's available regardless of what you're passing the argument to. – faho Jan 24 '20 at 16:28

score 3 · Answer 2 · answered Sep 06 '20 at 23:00

You can use echo -e (Enable interpretation of backslash escapes), as pointed out by @faho in his comment:

$ echo -e "## Foo\nBar"
## Foo
Bar

From man echo:

Escape sequences

   If -e is used, the following sequences are recognized:

   o \ backslash

   o \a alert (BEL)

   o \b backspace

   o \c produce no further output

   o \e escape

   o \f form feed

   o \n new line

   o \r carriage return

   o \t horizontal tab

   o \v vertical tab

   o \0NNN byte with octal value NNN (1 to 3 digits)

   o \xHH byte with hexadecimal value HH (1 to 2 digits)

score -2 · Answer 3 · answered Sep 29 '20 at 15:42

Edit your config.fish file.
Example in Ubuntu sudo nano /etc/fish/config.fish
Prompt function is what controls the appearance of the fish terminal. Paste this code:

# Put system-wide fish configuration entries here
# or in .fish files in conf.d/
# Files in conf.d can be overridden by the user
# by files with the same name in $XDG_CONFIG_HOME/fish/conf.d

# This file is run by all fish instances.
# To include configuration only for login shells, use
# if status --is-login
#    ...
# end
# To include configuration only for interactive shells, use
# if status --is-interactive
#   ...
# end
#

function fish_prompt -d "Write out the prompt"
    # change output color
    set -U fish_color_command             '2cff8f' -o

    # Aliases
    alias cls='clear'

    # Prompt
    printf '%s@%s%s%s%s\n@>' (whoami) (hostname | cut -d . -f 1) \
                    (set_color $fish_color_cwd) (prompt_pwd) (set_color normal)
end

I guess the gist is to do `printf 'first line\nsecond line'` — Dorian, Apr 02 '22 at 22:14

How can I have a newline in a string in fish shell?

3 Answers3

Escape sequences