Question

I am a newbie for shell script.

I noticed that for command like:

tar cf test.tar *TEST* *TEST2*

sh and bash will expand TEST to a list of file names, while csh will not.
I want the shell not to expend, how can I do this?

Use ‘ or ” will lead to other problems. If there is files match pattern *TEST*, but no files match *TEST2*,
then the tar will fail.

[EDIT]I think this is an expend difference between bash and csh.
When no pattern found for *TEST*, csh will expend to “”, while bash will expend to ‘TEST‘ (add quote char).

Answer 1

From man bash:

If the nullglob option is set, and no
matches are found, the word is
removed.

For example:

betelgeuse:TEST james$ touch TEST1 TEST3
betelgeuse:TEST james$ ls *TEST* *TEST2*
ls: *TEST2*: No such file or directory
TEST1   TEST3
betelgeuse:TEST james$ shopt -s nullglob
betelgeuse:TEST james$ ls *TEST* *TEST2*
TEST1   TEST3

This is approximately equivalent to the csh behaviour:

[betelgeuse:/tmp/TEST] james% ls *TEST* *TEST2*
TEST1   TEST3

The difference is that csh will return an error if all of the filename patterns on a line fail to match anything:

[betelgeuse:/tmp/TEST] james% ls *TEST4* *TEST2*
ls: No match.

while bash will just return an list of tokens to the command, leading to oddities such as this:

betelgeuse:TEST james$ ls *TEST4* *TEST2*
TEST1   TEST3

*TEST4* and *TEST2* both return nothing; so the ls command believes it has been called with no arguments and just gives a listing of the directory. In your example, tar would (rightly) complain that it’s being given no files to work on.