Can't get "echo" to work in a script!

[foobster]

Hello,

I'm trying to use echo in a script and it isn't working according to the man page. My demo script is as follows:

#! /bin/sh

echo -e -n "hello\nworld\n"
echo -n -e "hello\nworld\n"
echo -n  "hello\nworld\n"
echo -e  "hello\nworld\n"

And it outputs:

-e -n hello
world

-e hello
world
hello
world
-e hello
world

According to the manpage, I would expect -e to be a valid option and to be turned off by default (both of these things seem to be false here). Furthermore if I do the same in an interactive shell I get:

$ echo -e -n "hello\nworld\n"
hello
world
$ echo -n -e "hello\nworld\n"
hello
world
$ echo -n  "hello\nworld\n"
hello\nworld\n$ echo -e  "hello\nworld\n"
hello
world

just as I would expect. Piping the commands into bash also works as I would expect.

The command "which echo" returns "/bin/echo" from the script and from the interactive shell. I'm sure that I'm missing something here, but I can't for the life of me figure it out. Does anybody have any input? Thanks!

[cdtech]

What do you get running it in this manor?

echo -ne "hello\nworld\n"

[mikewu]

Change the #! /bin/sh to #!/bin/bash

I then get

hello
world
hello
world
hello\nworld\nhello
world

Not exactly sure why sh and bash are interpreting it differently, but it does fix it.

[foobster]

In the interactive shell I get what I would expect (-ne = -en = -e -n = -n -e). From the script I get:

-en hello
world

-ne hello
world

It doesn't like that e for some reason.

[foobster]

Thanks for the reply, I'm glad to have it working now. I'm still a little confused as to why it's like this. Also odd is that "echo --help" and "echo --version" don't work even though the man page says they should.

[foobster]

If anyone finds this post, here is a relevant link: https://bugs.launchpad.net/ubuntu/+s...ash/+bug/78116.

Here is another: https://bugs.launchpad.net/ubuntu/+s...ash/+bug/61463

The problem is just that most people are used to /bin/sh being linked to bash while in Ubuntu it is linked to dash. In dash, "-e" is not a valid option and escape characters are interpreted by default.

[cdtech]

Great find........Thanks.

[foobster]

Sorry, one more thing and I'll let this post die.

I found this link (https://wiki.ubuntu.com/DashAsBinSh) and it does a really great job of explaining why the /bin/sh link was changed to dash and what it means. It also explains some differences in syntax that you might get caught on if you're expecting it to be bash (echo for example). Also interesting is that "~" won't expand in dash. Interesting.

[kerry_s]

yeah, times have changed. i no longer use "/bin/sh" in my scripts, i use "/bin/dash" or "/bin/bash" depending on the script.
example, for something simple like a launcher:

#!/bin/dash
exec xmessage " Loading..... " -center -timeout 10 -buttons , | firefox &

i think it's better to just not assume and do it the right way.

[geirha]

There are three echos on your system.
1. The built-in echo in bash. Read its syntax in builtins(7) or bash(1).

$ bash
$ type echo
echo is a shell builtin

2. The built-in echo in dash. Read its syntax in dash(1)

$ sh
$ type echo
echo is a shell builtin

3. The separate command /bin/echo, which is the one explained by the man-page echo(1), and do accept --help and --version

/bin/echo --help
/bin/echo --version