nc://chmod-ref

Chmod Ref: a file mode, a chmod change or a umask explained in octal, ls -l and plain words. A Nodecode rewrite of olric3015/hermes-plugins by olric3015.

Get it

Tell the agent "add the chmod-ref cell", or run nodecode add nc://chmod-ref.

Use it

Ask about a mode and the model can call chmod_explain with the value it read, or ask for (nodecode-chmod-ref:explain "755") through eval. Typing /chmod 755 in the shell answers the same thing, and /chmod alone lists the examples.

755                     an octal mode (0755, 0o755 and 4-digit modes like 4755 too)
-rw-r--r--              ls -l text, with or without the file type letter (and + . @ after it)
100644                  an st_mode with the file type, as stat and git write it
644 u+x,go-w            a symbolic change applied to a mode, step by step
u+x,go-w                a symbolic change on its own, in words
100644 100755           what changes between two modes
umask 027               what new files and directories get

The answer for 100644 100755 and then u+x,go-w, as it comes back:

Mode 100644 -> 100755
  before    rw-r--r--  (100644)
  after     rwxr-xr-x  (100755)
  adds      execute for owner, group and others
Notes
  - this is the change git shows as old mode / new mode when a file's execute bit flips

Mode 100755 (rwxr-xr-x), a regular file
  octal     100755
  st_mode   100755 (file type and permission bits, as stat and git write them)
  ls -l     -rwxr-xr-x
  owner     read, write, execute
  group     read, execute
  others    read, execute
  special   none

chmod u+x,go-w
  u+x       add execute for the owner
  go-w      remove write from the group and others
  on 644    rwxr--r--  (744)
  on 755    rwxr-xr-x  (755)
Notes
  - give a starting mode to see one result: 644 u+x,go-w

Symbolic changes are applied the way GNU chmod applies them, with a umask of 0: u, g, o and a, the +, - and = operators (several in one clause, like u+r-w), r, w, x, X, s and t, and copies like u=g. On a directory, setuid and setgid are kept by = unless s is named, as GNU chmod does. A value that is not a mode answers why ("788" is not octal: 8 is not an octal digit (0-7)), and a wrong value in a tool call is recorded as a failed call.

What it says beyond the rows, when it applies:

• Special bits: what setuid, setgid and sticky do on a program and on a directory, that they are ignored where they are, and an S or T that means the bit is set without the matching execute.
• Who can do what: a mode no one but root can use, one everyone can change, one private to the owner (what ssh wants for keys), others able to write in a directory without the sticky bit, and a class with rights the class before it lacks.
• Files and directories: execute without read, a file read-only for its owner, and on a directory write without execute or read without execute.
• Types and git: a symbolic link's own mode, git's 160000 submodule entry, a file mode git would not keep, and the +, . and @ after ls -l bits.

Nothing on disk is read and nothing is changed: a value is a string, the answer is a string.

What is in it

The one setting is optional: max_target_chars (default 200) bounds how long a value is read.

Licence

MIT. The original is Copyright (c) 2026 olric3015: see LICENSE and NOTICE.