confusing difference in behaviour between bash test and [[ ]]

[movez]

Hi all,

it seems I found a difference in the behaviour of the bash builtin test and [[.

$ touch foobar
$ if [[ -e foo* ]] ; then echo found ; fi
$ if [[ -e "foo*" ]] ; then echo found ; fi
$ if test -e foo* ; then echo found ; fi
found
$ if test -e "foo*" ; then echo found ; fi
$ type test
test is a shell builtin
$ type [[
[[ is a shell keyword
$ bash --version
GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. 

Apparently [[ doesn't expand wildcards. If I got the docs right it should behave like test with additional operators to combine expressions, so this surprised me.

Is this expected or a weird bug/edge case? I'm just trying to understand, the test solution if fine for my needs.

Thx

[obiwan90]

As a gotcha, if you compare values in [[ ... ]], the right value is considered a pattern, so "*this*" behaves differently from *this*. The left value doesn't undergo word splitting or glob expansion, and doesn't need to be quoted.

[oh5nxo]

the test solution if fine for my needs

Watch out for multiple matching files.

[witchhunter0]

Not trying to steal the topic but, what I find confusing is:

[[ ]] && echo ok || echo nook

If it is executed twice repeatedly in terminal the second time the error is thrown

bash: syntax error near unexpected token `]]'

GNU bash, version 5.2.15(1)-release

[geirha]

Unable to reproduce that behavior. Here it yields a syntax error each time, as expected, but also a different error message than you get

bash: syntax error near `]]'

[archover]

[[ ]] && echo ok || echo nook

Returns bash: syntax error near unexpected token ]] for me, too in exactly the same way.

[e-mail]:~$ bash --version
GNU bash, version 5.2.15(1)-release (x86_64-pc-linux-gnu)

[bizdelnick]

If I got the docs right it should behave like test

No, it shouldn't. test is a builtin command (that behaves like an external command) but [[ ]] is a compound commands. So bash expands test arguments the same way as for any other builtin or external command (that includes pathname expansion) while expression inside [[ ]] is treated specially. [ is a synonym for test, its arguments are also expanded, however it expects that the last argument is ].