Bölüm 13 · Simülatör

Permissions Lab

← Bölüm 13
As
Mode
Speed 2/s
chmod 644 file.txt

Mode 0644 Class – Needs – Result – Step 0/0

Permissions Lab

How a Unix kernel decides whether a user may read, write or execute a file or directory: the mode bits (rwx for owner, group and others, plus setuid, setgid and sticky) and the first-match access check, shown step by step as a flowchart.

How to use

  • Pick the object type (File / Directory) and the operation; As fills in a user who is the owner, a group member or an unrelated user.
  • Edit owner, file group, requesting user and the user's groups (comma-separated) directly.
  • Toggle bits in the grid, type an octal mode, or choose a Mode preset. Every change replays the check; step through it with the playback buttons.
  • umask opens the umask calculator (new file and directory modes; Apply loads a result into the grid). Matrix shows who may do what for every class.

Rules

First match
Owner? use owner bits. Else in group? group bits. Else others.
r w x
4 + 2 + 1 per class digit.
Dir r
List names.
Dir w
Create, delete, rename entries; needs w and x.
Dir x
Search / traverse (cd, reach files by name).
setuid
4xxx: run with the owner's ID (s/S in owner x).
setgid
2xxx: run with the group; dirs pass on their group.
sticky
1xxx: in a dir, delete only your own files (t/T).
umask
Bits removed from 666 / 777 (mask, not subtraction).
Scope
Ordinary users only: no root, ACLs or parent-path checks.

Legend

class used needed bit set needed bit missing ✓ allowed✗ denied

Keys

←→ stepSpace replayHomeEnd first / lastEsc close