What does the mkdir command do?

The mkdir command creates directories (folders) in Linux and Unix systems. It can create single directories, multiple directories, or nested directory structures.

How do you create nested directories with mkdir?

Use 'mkdir -p path/to/nested/directory' to create nested directories. The -p option creates parent directories as needed.

What permissions does mkdir set by default?

mkdir sets default permissions based on umask, typically 755 (rwxr-xr-x) which gives full access to owner and read/execute to group and others.

mkdir Command

The mkdir command creates directories (folders) in Linux and Unix systems. It's essential for organizing files and creating directory structures for projects, data storage, and system administration.

Syntax

mkdir [options] directory_name...

Description

The mkdir command creates one or more directories with the specified names. If a directory already exists, mkdir will report an error unless you use specific options to handle this situation.

Key behaviors:

Creates directories with default permissions based on umask
Can create multiple directories in one command
Fails if parent directories don't exist (unless using -p)
Requires write permission in the parent directory

Common Options

Option	Description	Example
`-p`	Create parent directories as needed	`mkdir -p path/to/dir`
`-v`	Verbose mode (show created directories)	`mkdir -v newdir`
`-m`	Set directory permissions	`mkdir -m 755 dir`
`--help`	Display help information	`mkdir --help`
`--version`	Show version information	`mkdir --version`

Directory Permissions

Default directory permissions are calculated as: 777 - umask

777: Full permissions (rwxrwxrwx)
umask: Usually 022, removing write for group/others
Result: 755 (rwxr-xr-x) - owner can read/write/execute, others can read/execute

Examples

Create a single directory

mkdir documents

Creates a directory named "documents" in the current location

Create multiple directories

mkdir projects downloads music

Creates three directories: projects, downloads, and music

Create nested directories

mkdir -p projects/web/frontend/src

Creates the entire directory path, including all parent directories

Create directory with specific permissions

mkdir -m 700 private_folder

Creates directory with read/write/execute for owner only (700)

Verbose directory creation

                        mkdir -pv backup/2025/january

                        # Output: mkdir: created directory 'backup'

                        # mkdir: created directory 'backup/2025'

                        # mkdir: created directory 'backup/2025/january'

Shows each directory as it's created

Create directories with spaces in names

mkdir "My Documents" 'Project Files'

Use quotes to create directories with spaces in their names

Common Use Cases

Project Organization: Create directory structures for development projects
Backup Systems: Organize backups by date or category
Data Management: Separate different types of files and documents
System Administration: Create log directories and configuration folders
User Home Setup: Initialize directory structure for new users

💡 Tips and Best Practices

Use -p for scripts: Prevents errors if directories already exist
Meaningful names: Use descriptive directory names
Consistent naming: Follow a naming convention (lowercase, underscores, etc.)
Plan structure: Design directory hierarchy before creating
Check permissions: Ensure appropriate access levels for security

⚠️ Common Errors

"No such file or directory": Parent directory doesn't exist (use -p)
"Permission denied": No write access to parent directory
"File exists": Directory already exists (use -p to ignore)
"Invalid argument": Invalid characters in directory name