echo wildcard globing

Question

I'm trying to echo a combination of text and variables containing wildcards that I need "unpacked", but I encountered the following behavior:

If I say:

FILENAME=somefile*.txt
echo "something:" $FILENAME

I get:

something: somefile003.txt

Which is what I want, but if I say: If I say:

FILENAME=somefile*.txt
echo "something:"$FILENAME

I get:

something:somefile*.txt

So it seems like if there is no space between quotes and the variable it doesn't glob the wildcard. Is there a way to get it to process the * without adding a space?

It does try to parse the wildcard; there are just no files that match the glob something:somefile*.txt. — DopeGhoti, Jul 24 '17 at 18:09
If you say FILENAME = somefile*.txt your shell will try to execute a program called FILENAME. If you say FILENAME=somefile*.txt your shell will set a variable called FILENAME. Please be precise; it's important. — Chris Davies, Jul 24 '17 at 18:11
@DopeGhoti I see you've edited the question but how do you know which places really contain a space and which don't, given the question is about the effects seen when there is one or not? — Chris Davies, Jul 24 '17 at 18:14
The 'what I get' part of the question would be factually incorrect if there had been spaces as FILENAME would not have been assigned to something which could have globbed. — DopeGhoti, Jul 24 '17 at 18:15
Perhaps printf would help: printf "something:%s\n" $FILENAME. — jimmij, Jul 24 '17 at 18:16
Related - Bash substitution with variable defined from a glob pattern — Chris Davies, Jul 24 '17 at 18:21
@DopeGhoti Thanks for the edit, that is what I actually meant, I just typed it in incorrectly when writing the question — Maxim, Jul 24 '17 at 18:47

Chris Davies · Accepted Answer · 2023-09-08T07:38:54.240

5

with a shell that handles arrays such as bash you can glob into an array, thus

FILENAMES=(somefile*.txt)

and reference the first element like this

echo "something:${FILENAMES[0]}"

or all of them like this

echo "somethings:${FILENAMES[@]}"

I would strongly recommend that you "double quote" your variables when you use them. This avoids them being expanded into multiple words unexpectedly.

edited Sep 08 '23 at 07:38

answered Jul 24 '17 at 18:20

Chris Davies

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score 1 · Answer 2 · answered Jul 24 '17 at 18:28

Try to define your variable like this:

FILENAME=\ somefile*.txt; # that is, with a leading space ... and then
echo "something:"$FILENAME;

this gets variable interpolated to... something: somefile*.txt

then this gets wildcard expanded to... something: somefile003.txt

these two arguments then get passed to echo which promptly takes them stdout.

echo wildcard globing

2 Answers2