[solved] bash: difference `` and $()?

demian · 2010-05-14 11:37:41

Hey,

i'm new to bash scripting but I'm using both of the syntaxes `` and $() quite often and they seem to do the same thing.
I believe `` just evaluates and with $() i can do an array of evaluating sequences but i'm not sure and i didn't want to dig in too deep into some bash guides right now.

Can you tell me where the difference is?

Last edited by demian (2010-05-14 13:16:52)

Ogion · 2010-05-14 11:44:30

AFAIK you can nest $(one$(two$(three))) but now ``.

Ogion

Allan · 2010-05-14 11:47:09

Ogion wrote:

AFAIK you can nest $(one$(two$(three))) but now ``.

That is the main difference. For that reason the `` syntax is sort of depricated, but it has been in use so long that it will always be around.

Trent · 2010-05-14 13:14:00

I don't think $() is portable outside of bash. That's what I've heard, anyway.

tavianator · 2010-05-14 16:37:08

dash supports $(), and that's about as close to a strict POSIX shell as I've ever used.

JohannesSM64 · 2010-05-14 16:40:36

zsh also supports $(). You should always use $(), it's nestable and easier to read.

briest · 2010-05-14 17:54:18

man bash wrote:

To nest when using the backquoted form, escape the inner backquotes with backslashes.

But $() is indeed more readable.

Peasantoid · 2010-05-14 19:36:43

A quick web search turns up various relevant reasons, most already listed here.

note - Google doesn't seem to recognize '`' and '$()' in a query, so use 'backtick' instead.

Last edited by Peasantoid (2010-05-14 19:37:56)

tavianator · 2010-05-14 19:57:22

briest wrote:

man bash wrote:
To nest when using the backquoted form, escape the inner backquotes with backslashes.
But $() is indeed more readable.

Proof:

echo $(echo $(echo $(ls)))

vs.

echo `echo \`echo \\\`ls\\\`\``

eirika · 2010-05-14 20:23:46

Trent wrote:

I don't think $() is portable outside of bash. That's what I've heard, anyway.

$() is adopted and recommended by POSIX, so protability should not be a problem.
Search for command substitution in google and see by yourself

Last edited by eirika (2010-05-14 20:24:57)

Trent · 2010-05-14 23:06:29

Okay, okay, I can take a hint Apparently I was misinformed. I wonder where I picked that up.

Arch Linux

#1 2010-05-14 11:37:41

[solved] bash: difference `` and $()?

#2 2010-05-14 11:44:30

Re: [solved] bash: difference `` and $()?

#3 2010-05-14 11:47:09

Re: [solved] bash: difference `` and $()?

#4 2010-05-14 13:14:00

Re: [solved] bash: difference `` and $()?

#5 2010-05-14 16:37:08

Re: [solved] bash: difference `` and $()?

#6 2010-05-14 16:40:36

Re: [solved] bash: difference `` and $()?

#7 2010-05-14 17:54:18

Re: [solved] bash: difference `` and $()?

#8 2010-05-14 19:36:43

Re: [solved] bash: difference `` and $()?

#9 2010-05-14 19:57:22

Re: [solved] bash: difference `` and $()?

#10 2010-05-14 20:23:46

Re: [solved] bash: difference `` and $()?

#11 2010-05-14 23:06:29

Re: [solved] bash: difference `` and $()?

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