chmod - Change Permissions in Linux
From the Linux Essential Commands cheat sheet · File Permissions & Ownership · verified Jul 2026
chmod - Change Permissions
Modify file and directory access permissions
bash
# Numeric mode
chmod 755 file.sh # rwxr-xr-x
chmod 644 file.txt # rw-r--r--
chmod 600 private.key # rw-------
# Symbolic mode
chmod u+x script.sh # Add execute for user
chmod g-w file.txt # Remove write for group
chmod o+r file.txt # Add read for others
chmod a+x file.sh # Add execute for all
# Recursive
chmod -R 755 directory/✅ 755 = rwxr-xr-x (common for scripts and directories)
💡 644 = rw-r--r-- (common for regular files)
🔍 First digit=user, second=group, third=others
⚡ r=4, w=2, x=1 (add numbers for combinations)
permissionssecuritychmod
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