Bash by Example: Check Directory Exists
Verifying directory existence and creating it if missing using conditional logic with mkdir -p for parent directory creation, understanding the idempotent nature of mkdir -p that prevents errors when directories exist, implementing reliable directory setup in deployment scripts, and ensuring proper permissions for newly created directories.
Code
#!/bin/bash
dirname="logs"
# Check if directory exists
if [ -d "$dirname" ]; then
echo "Directory $dirname exists."
else
echo "Directory not found."
fi
# Create directory if it doesn't exist
if [ ! -d "$dirname" ]; then
echo "Creating directory..."
mkdir -p "$dirname"
fi
# Check if directory is empty
if [ -z "$(ls -A $dirname)" ]; then
echo "$dirname is empty"
else
echo "$dirname is not empty"
fi
rmdir "$dirname"Explanation
To check for directories, use the -d operator. This ensures the path exists and is specifically a directory.
A very common pattern in scripts is to check if a directory exists and create it if it doesn't. This prevents mkdir from throwing an "File exists" error, although mkdir -p also handles that gracefully.
Checking if a directory is empty is slightly trickier. ls -A lists all files (including hidden ones, but excluding . and ..). If the output of that command is empty string (checked with -z), the directory is empty.
Code Breakdown
[ -d ... ] returns true only if the path is a directory.mkdir -p creates parent directories as needed and doesn't complain if the directory already exists.ls -A is used because ls alone might miss hidden files (dotfiles), giving a false empty result.