Why does "echo" operate like "echo -e" in my bash?

Question

I stumbled upon a weird problem with echo on GNU bash, version 5.1.12(1)-release (x86_64-pc-solaris2.11):

bash-5.1$ builtin echo -e 'a\tb'
a       b

bash-5.1$ builtin echo 'a\tb'
a       b

bash-5.1$ builtin echo +e 'a\tb'
+e a    b

While it won't affect my scripts because I mostly use printf, how do you turn echo -e off in bash?

" The xpg_echo shell option may be used to dynamically determine whether or not echo expands these escape characters by default." . So run `shopt` and see if it's enabled. — nos, Apr 18 '23 at 19:33
Even tho the prompt says bash, are you sure you're not using a shell like `zsh` where `-e` is enabled by default? — 0stone0, Apr 18 '23 at 19:35
@0stone0 nope, my prompt turned out like this after typing `bash` — Fravadona, Apr 18 '23 at 19:36
@nos you can post `shopt -u xpg_echo` as an answer, I'll accept it — Fravadona, Apr 18 '23 at 19:37
xpg_echo is on by default on solaris since long before bash 5.1 — oguz ismail, Apr 18 '23 at 19:57
@oguzismail That's indeed true. I didn't notice it with the bash 4.x of Solaris 11.3/11.4... — Fravadona, Apr 18 '23 at 20:01
yeah. if I recall correctly it's the same on macos, aix, hp-ux, and z/os too. that's why printf is preferred — oguz ismail, Apr 18 '23 at 20:02
this is one of the reasons people recommend using `printf` instead of `echo`. — pynexj, Apr 19 '23 at 06:52

score 4 · Accepted Answer · answered Apr 18 '23 at 19:37

4

You have the xpg_echo shell option enabled.

List the options by running shopt

Disable it with shopt -u xpg_echo

To figure this out, read the echo section of man builtins (assuming that gives you the bash builtin commands, otherwise look at https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html)

The relevant part is

The xpg_echo shell option may be used to dynamically determine whether or not echo expands these escape characters by default.

answered Apr 18 '23 at 19:37

nos

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It's true that it is an old option (bash 3.2 have it), but it's my first time getting it turned on by default... – Fravadona Apr 18 '23 at 19:40
1

@Fravadona There might be a .bashrc/.bash_profile for your user or globally on that particular machine that turns it on – nos Apr 19 '23 at 09:21

score 2 · Answer 2 · answered May 05 '23 at 11:50

Since there are many possible ways for the xpg_echo option to get turned on, the safest option when you want to ensure that echo will not interpret backslash escapes may be to always use the -E option. However, code like

echo -E "$var"

still doesn't work in general because "$var" might expand to an echo option. I find it best to use echo only for simple literal strings, if at all. Also see the accepted, and excellent, answer to Why is printf better than echo?.

Why does "echo" operate like "echo -e" in my bash?

2 Answers2