Shell script: Brace expansion

[SGK]

Hi,

The following two brace expansion working differently. Can someone explain how this works?

# echo {file1,file2}\ :{\ A," B",' C'}
file1 : A file1 : B file1 : C file2 : A file2 : B file2 : C

# echo {file1,file2} :{\ A," B",' C'}
file1 file2 : A : B : C

TIA.

[Ivan Ferreira]

I just tested both expressions and I have the same result. That is, both returns the same output:

file1 : A file1 : B file1 : C file2 : A file2 : B file2 : C

[SGK]

Under which shell you tried?

# echo $SHELL
/bin/bash

# echo {file1,file2} :{\ A," B",' C'}
file1 file2 : A : B : C

[Jeroen Peereboom]

>echo $SHELL
/bin/bash
> echo {file1,file2}\ :{\ A," B",' C'}
file1 : A file1 : B file1 : C file2 : A file2 : B file2 : C
>echo {file1,file2}\ :{\ A," B",' C'}
file1 : A file1 : B file1 : C file2 : A file2 : B file2 : C

No differences?

JP

[Alexander Chuzhoy]

I get the same behavior as you did.
Use BASH shell on rhel4.2

[Jeroen Peereboom · Accepted solution]

Oops...

>echo {file1,file2}\ :{\ A," B",' C'}
file1 : A file1 : B file1 : C file2 : A file2 : B file2 : C
>echo {file1,file2} :{\ A," B",' C'}
file1 file2 : A : B : C

Difference in commands: the back-slash to escape the space before the colon.
Man page:
A correctly-formed brace expansion must contain unquoted opening and closing braces, and at least one unquoted comma. Any incorrectly formed brace expansion is left unchanged.
I don't think that helps.

If you escape the space with a backslash, the space is part of the string. If you do not escape the space, it is a separator and there is nothing to expand in the two separate brace lists...

JP

[Jeroen Peereboom]

And also:

echo {file1,file2}" : "{\ A," B",' C'}
file1 : A file1 : B file1 : C file2 : A file2 : B file2 : C

JP

[Ryan Goh]

Try this

# echo {file1,file2}:{\ A," B",' C'}

You should get the result below:

file1: A file1: B file1: C file2: A file2: B file2: C

Because of additional space in between of } and : , that why get the problem look like below:


file1 file2 : A : B : C

[SGK]

Thanks all to clarify my doubts