Bash Wildcards – Expanding Item with Curly Braces

bashwildcards

If I use bash's brace expansion I get a list

echo item={one,two,three}
item=one item=two item=three

Assuming I am in a directory with files/folders that would match a wildcard, is there any way to have an expansion that matches these files/folders?

ls
blue  green  red

echo item=*      # Obviously not
item=*

echo item={*}    # Maybe? ...but no
item={*}

In my example I would like the expansion to be item=blue item=green item=red

The best I've got so is code like this

items=()
for dirent in *; do items+=("item=$dirent"); done
echo "${items[@]}"

item=blue item=green item=red

Best Answer

You can store the current directory’s files in an array as follows:

items=(*)

Then parameter expansion can be used to add the prefix:

printf "%s\n" "${items[@]/#/item=}"

You can use this to update the array:

items=("${items[@]/#/item=}")

Related Solutions

Bash wildcard not expanding

A wildcard always expands to existing names.

Your command mkdir * fails because the names that * expands to already exists.

Your command mkdir *.d "fails" because the *.d does not match any existing names. The pattern is therefore left unexpanded by default¹ and a directory called *.d is created. You may remove this with rmdir '*.d'.

To create a directory for each regular file in the current directory, so that the new directories have the same name as the files, but with a .d suffix:

for name in ./*; do
    if [ -f "$name" ]; then
        # this is a regular file (or a symlink to one), create directory
        mkdir "$name.d"
    fi
done

or, for people that like "one-liners",

for n in ./*; do [ -f "$n" ] && mkdir "$n.d"; done

In bash, you could also do

names=( ./* )
mkdir "${names[@]/%/.d}"

but this makes no checks for whether the things that the glob expands to are regular files or something else.

The initial ./ in the commands above are to protect against filenames that contain an initial dash (-) in their filenames. The dash and the characters following it would otherwise be interpreted as options to mkdir.

¹ _{Some shells have a nullglob shell option that causes non-matched shell wildcards to be expanded to an empty string. In bash this is enabled using shopt -s nullglob.}

Bash Wildcards – Wildcard Not Expanding Hidden Files

I figured it out! Looking more closely at the documentation for shopt, there's an option called dotglob that can be used to include filenames that begin with a dot!

I added shopt -s dotglob to the beginning of my script and it works now. The output now lists every hidden file and directory (except ./ and ../).

My script now looks like this:

#!/bin/bash
shopt -s extglob
shopt -s dotglob

for i in "$(pwd)"/*; do
  echo "$i"
done

Best Answer

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