Chmod-Kalkylator

Beräkna Unix-filrättigheter med interaktiva kryssrutor, oktal och symbolisk notation

Funktioner

Bidirectional sync: octal (e.g. 755) ↔ symbolic (e.g. rwxr-xr-x)
3-digit and 4-digit octal modes — special bits (SUID, SGID, sticky) supported via the optional 4th digit
Per-bit checkboxes for owner / group / others + separate toggles for SUID, SGID, sticky
`chmod` command preview (octal form) and `chmod u=…,g=…,o=…` symbolic form
Runs entirely in your browser

Så använder du

Toggle the read, write, and execute checkboxes for each user group.
Or type an octal value (e.g., 755) in the input field.
Or click a common preset button.
Copy the generated chmod command to use in your terminal.

Tips och bästa praxis

4-digit octal: the first digit is SUID (4) + SGID (2) + sticky (1). Common combinations: 4755 (suid binary), 2755 (sgid binary), 1777 (sticky directory like /tmp).
Sticky bit on a directory means only the owner can delete files inside, even with write permission (think /tmp).
SUID on an executable runs as the file owner — security-sensitive; use sparingly.
Symbolic output replaces `x` with `s` for SUID/SGID and `t` for sticky; uppercase letters (S, T) indicate the special bit is set but execute is OFF.
For typical web-app files, 644 (regular files) and 755 (directories / scripts) cover most cases.

Vanliga frågor

What does chmod 755 mean?

755 means the owner can read, write, and execute (7), while group and others can only read and execute (5). This is the standard permission for directories and executable scripts.

What does chmod 644 mean?

644 means the owner can read and write (6), while group and others can only read (4). This is the standard permission for regular files.

What is the difference between octal and symbolic notation?

Octal uses numbers (e.g., 755) while symbolic uses letters (e.g., rwxr-xr-x). Both achieve the same result — octal is more concise, symbolic is more readable.

chmod Commands