In addition to the basic *
, ?
and [...]
patterns, the Bash shell provides extended pattern matching operators like !(pattern-list)
("match all except one of the given patterns"). The extglob
shell option needs to be set to use them. An example:
~$ mkdir test ; cd test ; touch file1 file2 file3
~/test$ echo *
file1 file2 file3
~/test$ shopt -s extglob # make sure extglob is set
~/test$ echo !(file2)
file1 file3
If I pass a shell expression to a program which executes it in a sub-shell, the operator causes an error. Here's a test which runs a sub-shell directly (here I'm executing from another directory to make sure expansion doesn't happen prematurely):
~/test$ cd ..
~$ bash -c "cd test ; echo *"
file1 file2 file3
~$ bash -c "cd test ; echo !(file2)" # expected output: file1 file3
bash: -c: line 0: syntax error near unexpected token `('
bash: -c: line 0: `cd test ; echo !(file2)'
I've tried all kinds of escaping, but nothing I've come up with has worked correctly. I also suspected extglob
is not set in a sub-shell, but that's not the case:
~$ bash -c "shopt -s extglob ; cd test ; echo !(file2)"
bash: -c: line 0: syntax error near unexpected token `('
bash: -c: line 0: `cd test ; echo !(file2)'
Any solution appreciated!
bash parses each line before executing it, so "shopt -s extglob" won't have taken effect when bash is validating the globbing pattern syntax. The option can't be enabled on the same line. That's why the "bash -O extglob -c 'xyz'" solution (from Randy Proctor) works and is required.
$ bash -O extglob -c 'echo !(file2)' file1 file3
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