Echo new line and string beginning \t

Question

Sure, echo -e can be used so that \n is understood as a new line. The problem is when I want to echo something beginning with \t e.g. "\test".

So let's say I want to perform echo -e "test\n\\test". I expect this to output:

test
\test

But instead outputs:

test
  est

The \\t is being interpreted as a tab instead of a literal \t. Is there a clean workaround for this issue?

Answer 1

echo -e "\\t"

passes \t to echo because backslash is special inside double-quotes in bash. It serves as an escaping (quoting) operator. In \\, it escapes itself.

You can either do:

echo -e "\\\\t"

for echo to be passed \\t (echo -e "\\\t" would also do), or you could use single quotes within which \ is not special:

echo -e '\t'

Now, echo is a very unportable command. Even in bash, its behaviour can depend on the environment. I'd would advise to avoid it and use printf instead, with which you can do:

printf 'test\n\\test\n'

Or even decide which parts undergo those escape sequence expansions:

printf 'test\n%s\n' '\test'

Or:

printf '%b%s\n' 'test\n' '\test'

%b understands the same escape sequences as echo (some echos), while the first argument to printf, the format, also understands sequences, but in a slightly different way than echo (more like what is done in other languages). In any case \n is understood by both.

Answer 2

This is not in accordance with manual for the command, but man itself states point 1:

1. Echo depends on your shell (and there are other reasons sometimes to avoid it, like piping).
2. Stéphane's comment is not a bad way to go: printf it.
3. echo solution echo -e "a\na\ta" (double quotes, read up on what they do though if you want to expand that code for something more) and tests:

`

➜  ~ echo -e a \n a \ta
a n a ta
➜  ~ echo -e "a \n a \ta"
a 
 a  a
➜  ~ echo -e "a\na\ta"   
a
a   a
➜  ~ bash                
T420s:~$ echo -e "a\na\ta"
a
a   a
T420s:~$ echo -e a\na\ta
anata
T420s:~$ echo a\na\ta
anata
T420s:~$ echo "a\na\ta"
a\na\ta
T420s:~$ 

First shell is ZSH.

Answer 3

The shell snippet "test\n\\test" expands to the string test\n\test, because a backslash inside double quotes causes the next character to be interpreted literally if the next character is one of "$\` and otherwise the backslash itself is interpreted literally. Then echo -e replaces \n with a newline and \t with a tab.

Avoid double quotes to quote literal text. Use single quotes instead: they have simpler rules — everything inside single quotes is interpreted literally is a single quote. If you choose to use double quotes, don't use backslashes that are not followed by a character that it would quote — if you want a backslash inside double quotes, use \\.

echo -e 'test\n\\test'
echo -e "test\\n\\\\test"