New line in variable

Question

I want to create a config file with a .sh file. I can't figure out how i insert new lines.

The code i already have:

domainconf='<VirtualHost *:80>\n ServerName '$fulldomain'\n DocumentRoot '$fullpath'\n </VirtualHost>'
echo $domainconf > /etc/apache2/sites-available/"$fulldomain".conf

Hugely important to quote your variables. Please read https://unix.stackexchange.com/q/171346/4667 — glenn jackman, Jul 05 '16 at 15:51

Kusalananda · Answer 1 · 2016-07-05T15:15:50.237

5

If all you need to do is to write the configuration to a file, then the following would be more readable, and it does away with the need for a variable:

cat >/etc/apache2/sites-available/"$fulldomain".conf <<END_CONFIG
<VirtualHost *:80>
ServerName '$fulldomain'
DocumentRoot '$fullpath'
</VirtualHost>
END_CONFIG

If you absolutely need the thing in a variable:

conf=$(cat <<END_CONFIG
<VirtualHost *:80>
ServerName '$fulldomain'
DocumentRoot '$fullpath'
</VirtualHost>
END_CONFIG
)

echo "$conf" >/etc/apache2/sites-available/"$fulldomain".conf

edited Jul 05 '16 at 15:15

answered Jul 05 '16 at 14:31

Kusalananda

333,661

Does command substitution need double quoting? – Kevin Jul 05 '16 at 19:36
@Kevin You may quote the command substitution if you wish, but it's not necessary here (because here-document). The important bit is the quoting of $conf in echo "$conf". – Kusalananda Jul 06 '16 at 06:02
1

@Kevin I'm actually unsure about it, but since I can't seem to get it to fail without quoting (for various odd here-doc contents), I believe it's safe. Please feel free to prove me wrong. – Kusalananda Jul 06 '16 at 06:04
2

@Kevin not when it is the value in an assignment, although otherwise it usually does. Kusalananda: Try echo $( cat <<STR eol lines eol STR eol ) to see the failure case. – dave_thompson_085 Jul 06 '16 at 06:14
@dave_thompson_085 Much appreciated, thanks! – Kusalananda Jul 06 '16 at 06:30

score 2 · Answer 2 · edited Jul 05 '16 at 15:13

2

Just echo with '-e' flag

domainconf='<VirtualHost *:80>\n ServerName '$fulldomain'\n DocumentRoot '$fullpath'\n </VirtualHost>'
echo -e "$domainconf" > /etc/apache2/sites-available/"$fulldomain".conf

edited Jul 05 '16 at 15:13

terdon

242,166

answered Jul 05 '16 at 14:10

Tejas Patel

41

1

Welcome to Unix & Linux @Patrick! If this answer solved your issue, please take a moment and accept it by clicking on the check mark to the left. That will mark the question as answered and is the way thanks are expressed on the Stack Exchange sites. – terdon Jul 05 '16 at 15:12

score 2 · Answer 3 · answered Jul 05 '16 at 14:31

2

Another option is to embed literal newlines in the script:

% cat newl  
blah='x
y
z'

echo "$blah"
% sh newl 
x
y
z
%

Do note the quotes on $blah!

answered Jul 05 '16 at 14:31

thrig

34,938

Quentin Morrier · Answer 4 · 2016-07-05T14:50:11.987

1

Try to replace echo by printf

domainconf='<VirtualHost *:80>\n ServerName '$fulldomain'\n DocumentRoot '$fullpath'\n </VirtualHost>'
printf "$domainconf" > /etc/apache2/sites-available/"$fulldomain".conf

edited Jul 05 '16 at 14:50

answered Jul 05 '16 at 14:42

Quentin Morrier

167

printf is a pretty good solution, but not the way you've used it (which is no better than echo). Try domfmt='<VirtualHost *:80>\n ServerName %s\n DocumentRoot %s\n </VirtualHost>' followed by printf "$domfmt" "$fulldomain" "$fullpath" > "/etc/apache2/sites-available/$fulldomain.conf" – cas Jul 06 '16 at 01:04

New line in variable

4 Answers4