Bash function that returns matches for *a*/*b*/*c*/*d* based on input of a/b/c/d?

Question

Basically, I'd like to write a bash script or function where given an input of a/b/c/d, it would return all matches where each path component had wildcards at the start and end, e.g. *a*/*b*/*c*/*d*. It would be nice to respect the tilde (~) as home folder as well.

Is there an easy way to do this in bash or do I need to do this in something like Python?

Answer 1

I'll give you a starting point:

x="a/b/c/d"                                                                     
x="*${x//\//*\/*}*"                                                             
echo $x
# output: "*a*/*b*/*c*/*d*", or all matching paths (if any)

This solution is far from perfect. Specifically you'd have to solve the following problems:

• x may contain special characters like spaces or * characters. They need to be properly escaped.
• x may contain double slashes. For example: x=a//b. I think you want it to become *a*/*b*, not *a*/**/*b*.
• x may contain leading or trailing slashes. For example: x=/a/b or x=a/b/.
• x may start with a tilde.

All these problems may be solved with if statements and replacements.

---

Another approach (that requires more code, but is probably safer and less error prone) is to parse and interpret the string with a loop, like this:

shopt -s nullglob

x="a/b/c/d"
IFS=/ read -a x <<< "$x"
# x is now an array in the form (a b c d)

result=(*"${x[0]}"*)

for c in "${x[@]:1}"
do
    newresult=()
    for r in "${result[@]}"
    do
        match=("$r"/*"$c"*)
        [ "${#match[@]}" -gt 0 ] && \
            newresult=("${newresult[@]}" "${match[@]}")
    done
    result=("${newresult[@]}")
done

echo "${result[@]}"

Again, this is not perfect. Problems include:

• You have to deal with double slashes.
• You have to deal with leading and trailing slashes.
• You still have to deal with the tilde.

This solution is nice because these problems are easier to handle, also you don't have to worry about special characters.