The Problem

Need to check if a directory exists before doing something with it? Here’s how to do it properly in Bash!

Basic Directory Check

#!/bin/bash

test_dir_exist(){
    set -e 
    if [ -e "/home/jayleekr/workspace/00_codes/05_info_archive" ]; then
        echo "DIR Exist"
        exit 1
    fi
}

test_fail(){
    echo "test_fail"
}

test_dir_exist

Running this:

$ ./directory_ex.sh
DIR Exist

Better Approaches

1. Using -d for Directory-Specific Check

#!/bin/bash

check_directory() {
    local dir_path="$1"
    
    if [ -d "$dir_path" ]; then
        echo "✅ Directory '$dir_path' exists"
        return 0
    else
        echo "❌ Directory '$dir_path' does not exist"
        return 1
    fi
}

# Usage
check_directory "/home/user/workspace"

2. Create Directory if It Doesn’t Exist

#!/bin/bash

ensure_directory() {
    local dir_path="$1"
    
    if [ ! -d "$dir_path" ]; then
        echo "Creating directory: $dir_path"
        mkdir -p "$dir_path"
    else
        echo "Directory already exists: $dir_path"
    fi
}

# Usage
ensure_directory "/tmp/my_project/logs"

3. Multiple Directory Checks

#!/bin/bash

check_multiple_dirs() {
    local dirs=("$@")
    local all_exist=true
    
    for dir in "${dirs[@]}"; do
        if [ ! -d "$dir" ]; then
            echo "❌ Missing: $dir"
            all_exist=false
        else
            echo "✅ Found: $dir"
        fi
    done
    
    if [ "$all_exist" = true ]; then
        echo "🎉 All directories exist!"
        return 0
    else
        echo "💥 Some directories are missing!"
        return 1
    fi
}

# Usage
check_multiple_dirs "/tmp" "/home" "/var/log" "/nonexistent"

Different Test Operators

Here are the different ways to test for files and directories:

# -e: exists (file or directory)
[ -e "/path" ] && echo "Something exists at /path"

# -f: regular file exists
[ -f "/path/file.txt" ] && echo "File exists"

# -d: directory exists
[ -d "/path/dir" ] && echo "Directory exists"

# -r: readable
[ -r "/path" ] && echo "Readable"

# -w: writable
[ -w "/path" ] && echo "Writable"

# -x: executable
[ -x "/path" ] && echo "Executable"

Practical Examples

1. Backup Script

#!/bin/bash

BACKUP_DIR="/backup/$(date +%Y%m%d)"

if [ ! -d "$BACKUP_DIR" ]; then
    echo "Creating backup directory: $BACKUP_DIR"
    mkdir -p "$BACKUP_DIR"
fi

echo "Backing up to: $BACKUP_DIR"
# Your backup commands here...

2. Project Setup

#!/bin/bash

setup_project() {
    local project_name="$1"
    local project_dirs=("$project_name/src" "$project_name/tests" "$project_name/docs")
    
    for dir in "${project_dirs[@]}"; do
        if [ ! -d "$dir" ]; then
            echo "Creating: $dir"
            mkdir -p "$dir"
        fi
    done
    
    echo "Project structure created for: $project_name"
}

# Usage
setup_project "my_awesome_app"

3. Log Rotation Check

#!/bin/bash

LOG_DIR="/var/log/myapp"
ARCHIVE_DIR="/var/log/myapp/archive"

if [ -d "$LOG_DIR" ]; then
    echo "Log directory exists"
    
    # Create archive directory if needed
    [ ! -d "$ARCHIVE_DIR" ] && mkdir -p "$ARCHIVE_DIR"
    
    # Rotate logs
    find "$LOG_DIR" -name "*.log" -mtime +7 -exec mv {} "$ARCHIVE_DIR" \;
else
    echo "Log directory not found: $LOG_DIR"
    exit 1
fi

Pro Tips

1. Always quote variables: [ -d "$dir" ] not [ -d $dir ]
2. Use -d for directories: More specific than -e
3. Handle spaces in paths: Quoting protects against spaces
4. Exit codes matter: Return meaningful exit codes for scripting
5. Create parent directories: Use mkdir -p to create nested directories

Common Pitfalls

# ❌ Don't do this
if [ -d $HOME/my dir ]; then  # Breaks with spaces!

# ✅ Do this instead
if [ -d "$HOME/my dir" ]; then  # Properly quoted

# ❌ Don't do this
if [ -e "$dir" ]; then  # Could be a file!

# ✅ Do this for directories
if [ -d "$dir" ]; then  # Specifically checks for directory

References

• General: Bash Beginners Guide
• Test operators: man test or help test

Directory checks are fundamental - get them right and your scripts will be much more robust! 🚀