Linux umask Guide

Linux umask Guide

Complete beginner-friendly guide to umask on Linux, covering Arch Linux, CachyOS, and other distributions including file permission masks, default permissions, and permission control.

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Table of Contents

1. umask Basics
2. Viewing umask
3. Setting umask
4. Permission Calculation
5. Troubleshooting

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umask Basics

View umask

Basic usage:

# View current umask
umask

# Shows current umask value

Symbolic Format

Symbolic output:

# Symbolic format
umask -S

# -S = symbolic (human-readable)

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Viewing umask

Current Value

Current umask:

# Current umask
umask

# Output: 0022 (octal)

Symbolic Display

Human-readable:

# Symbolic display
umask -S

# Output: u=rwx,g=rx,o=rx

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Setting umask

Set umask

Change umask:

# Set umask
umask 022

# Sets umask to 022

Symbolic umask

Symbolic format:

# Symbolic umask
umask u=rwx,g=rx,o=

# Sets permissions via symbolic format

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Permission Calculation

How umask Works

Calculation:

# Default file: 666 (rw-rw-rw-)
# umask: 022 (----w--w-)
# Result: 644 (rw-r--r--)

# Default directory: 777 (rwxrwxrwx)
# umask: 022 (----w--w-)
# Result: 755 (rwxr-xr-x)

Common umask Values

Common values:

# 022 = rw-r--r-- (files), rwxr-xr-x (dirs)
umask 022

# 002 = rw-rw-r-- (files), rwxrwxr-x (dirs)
umask 002

# 077 = rw------- (files), rwx------ (dirs)
umask 077

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Troubleshooting

umask Not Found

Check installation:

# umask is built-in shell command
# Always available in bash

# Check bash
which bash

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Summary

This guide covered umask usage, file permission masks, and default permissions for Arch Linux, CachyOS, and other distributions.

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Next Steps

• chmod Guide - Change permissions
• File Permissions - Permission guide
• User and Groups - User management
• umask Documentation: man bash (built-in)

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This guide covers Arch Linux, CachyOS, and other Linux distributions. For distribution-specific details, refer to your distribution's documentation.