A star is being printed for an empty directory after running a script to list the subfolder

Question

I was trying to write a shell script that will take a directory path d as an argument and recursively print a depth indented list of all files and directories in d. However, the argument d is optional and if no argument is given, a depth indented list of all files and directories​ ​in​ ​the​ ​current​ ​ directory​ will​ ​be printed. Here is my code:

# the method for tree
myspace=""
spaceCount=0
tree(){

  cd "$1"
  for i in *; do
    if [ -d "$i" ]; then
      echo -n "|"

      for (( j=0;j<spaceCount;j++ )) 
      do 
        echo -n "$myspace"

      done
      echo "--$i"
      spaceCount=$((spaceCount+1)) 
      myspace="  |"
      tree "$i"
    else
      echo -n "|"
      for (( j=0;j<spaceCount;j++ )) 
      do 
        echo -n "$myspace"

      done
      echo "--$i"
    fi
  done
  cd ../
  spaceCount=$((spaceCount-1))
}
if [ "$1" != "" ]; then
  file="$1"
fi
echo ".$file"
tree "$file"

But when a folder is empty, it's printing a star like this:

How can I solve the problem?

Answer 1

In bash and Bourne-like shells in general (zsh being the exception), globs like * that match no file expand to themselves (your script uses ksh93 syntax, also recognised by bash and zsh, though in zsh you'd get fatal errors by default for non-matching globs).

echo * in a directory that contains no file (or only hidden files) outputs *.

Here instead of for i in *, use for i in *(N) (zsh) or for i in ~(N)* (ksh93) or if using bash, set the nullglob option (with shopt -s nullglob) so that the globs that don't match expand do nothing.

Alternatively, you could add a [ -e "$i" ] || continue at the start or your for loop to filter out the * by checking for file existence (would affect the behaviour for directories you have read but not search permissions to though¹).

More reading at Why is nullglob not default?

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^{¹ In those directories, * would expand to all the non-hidden files, but [ -e "$i" ] would return false for everyone of them as the stat() system call would return with permission denied}