Máy tính Chmod - Lưới quyền file Linux
Thay vì ghi nhớ mã octal, hãy chọn Read, Write và Execute cho Owner, Group và Public - Dokall hiển thị ngay giá trị octal, ký hiệu symbolic và lệnh chmod sẵn sàng dán.
Preset phổ biến gồm 755 cho thư mục web, 644 cho file, 600 cho SSH key và 400 cho PEM key chỉ đọc. Sửa tên file để tùy chỉnh lệnh terminal trước khi sao chép.
Frequently Asked Questions
What is chmod?
chmod (change mode) is a Unix/Linux command that sets file permissions. It controls who can read, write, and execute a file - the owner, the group, and everyone else.
What do the numbers in chmod 755 mean?
Each digit represents permissions for owner, group, and others. 7 = read(4) + write(2) + execute(1). 5 = read(4) + execute(1). So 755 means owner has full access, group and others can read and execute but not write.
What is the difference between files and directories?
Execute permission on a file means it can be run as a program. Execute on a directory means you can cd into it and list its contents. Directory permissions 755 (rwxr-xr-x) are standard; file permissions 644 (rw-r--r--) are common for regular files.
What does chmod 777 do?
777 grants read, write, and execute to everyone - owner, group, and others. This is a security risk on servers because any user can modify the file. Use 755 for directories and 644 for files unless you have a specific reason for broader access.
Symbolic vs numeric notation?
Numeric (755) is compact and common in tutorials. Symbolic (u=rwx,g=rx,o=rx) is more readable and used in chmod commands with letters: chmod u+x file adds execute for the owner. Dokall converts between both formats.