How do I check if a directory exists or not in a Bash shell script?

To check if a directory exists in a Bash script, you can use the -d test operator in a conditional statement. Here’s how to do it:

Basic Syntax

if [ -d "/path/to/directory" ]; then
    echo "Directory exists."
else
    echo "Directory does not exist."
fi

Key Components

1. -d: Checks if the path exists and is a directory.
2. Quotes: Use " " around paths with spaces (e.g., "/path/with spaces").
3. Variables: Use variables to make paths dynamic:

   dir="/path/to/directory"
   if [ -d "$dir" ]; then
       echo "$dir exists."
   fi

Common Use Cases

1. Create a Directory If It Doesn’t Exist

dir="/path/to/directory"
if [ ! -d "$dir" ]; then
    mkdir -p "$dir"
    echo "Created $dir"
fi

• ! negates the condition (checks for non-existence).
• mkdir -p creates parent directories if needed.

2. Check Multiple Directories

directories=("/etc" "/invalid/path" "/tmp")
for dir in "${directories[@]}"; do
    if [ -d "$dir" ]; then
        echo "$dir ✔️"
    else
        echo "$dir ❌"
    fi
done

3. Handle Symlinks

To check if a path is a directory and not a symlink:

if [ -d "/path" ] && [ ! -L "/path" ]; then
    echo "Real directory (not a symlink)."
fi

• -L checks if the path is a symbolic link.

Edge Cases & Notes

• Spaces in Paths: Always quote variables/paths to handle spaces:

  # Bad (fails for paths with spaces):
  if [ -d $dir ]; then ...

  # Good:
  if [ -d "$dir" ]; then ...

• Permissions: The script needs execute permission on the directory’s parent to check existence.
• Empty Variable: If dir is unset, [ -d "$dir" ] returns false.

Alternative: test Command

The test command is equivalent to [ ]:

test -d "/path/to/dir" && echo "Exists" || echo "Does not exist"

Example Output

$ ./check_dir.sh
Directory /etc ✔️
Directory /invalid/path ❌

Let me know if you need further refinements!