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doru	12-17-2014 03:14 PM

bash for strange expansion

Code:

touch a b a\(c\)b

$ ls *\(c\)*

a(c)b

$ for a in *\(c\)*; do ls $a; done

a(c)b

# this is ok 

rm a\(c\)b

$ ls *\(c\)*

ls: cannot access *(c)*: No such file or directory

$ for a in *\(c\)*; do ls $a; done

a  b

# this is not clear. please tell me why would this happen?!

smallpond

12-17-2014 03:37 PM

Does this give you the behavior you expect?

Code:

shopt -s nullglob

doru	12-17-2014 04:28 PM

Quote:

Originally Posted by smallpond (Post 5286516)

Does this give you the behavior you expect?

Code:

shopt -s nullglob

Yes it does, thank you for your answer.
Why would be ls inconsistent with for, and why would *\(c\)* expand to the list of files as one word? I should be able to understand it by myself starting from here.

jpollard

12-17-2014 04:35 PM

Looks like you deleted the file.

suicidaleggroll

12-17-2014 04:40 PM

Put quotes around your variable in the for loop, same as you would if there's a space or any other "bad" character.

Code:

$ touch a b

for a in *\(c\)*; do ls $a; done

a  b

$ for a in *\(c\)*; do ls "$a"; done

ls: cannot access *(c)*: No such file or directory

same as this

Code:

$ touch "a b"

$ ls *\ *

a b

$ for a in *\ *; do ls $a; done

ls: cannot access a: No such file or directory

ls: cannot access b: No such file or directory

$ for a in *\ *; do ls "$a"; done

a b

If there's ever a chance you're going to have a character that requires delimiting (-, (, space, etc.) stored inside a variable, then you need to stick quotes around it when you use it.

doru	12-18-2014 02:34 PM

Sorry to bother you again, but please tell me why does this happen. () should introduce some subshell which here should result in an error.

Code:

$ ls *()*

a  a(c)b  a(c)c  b

$ ls *()

ls: cannot access *(): No such file or directory

$ ls ()*

bash: syntax error near unexpected token `('

$

doru	12-18-2014 02:48 PM

Quote:

Originally Posted by doru (Post 5287068)

Sorry to bother you again, but please tell me why does this happen. () should introduce some subshell which here should result in an error.

Code:

$ ls *()*

a  a(c)b  a(c)c  b

$ ls *()

ls: cannot access *(): No such file or directory

$ ls ()*

bash: syntax error near unexpected token `('

$

OK, so *() is some pattern matching in pathname expansion. So bash is looking for some file with a void name? OK, so nothing matches nothing, that's right. I did fall into a succession of traps here, did I not? Thank you all, :)

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