# Chmod mode convert

`chmod-mode-convert` · version 1.0.0 · Developer tools · free, no key needed

Convert a Unix permission mode and apply explicit chmod symbolic clauses, returning canonical octal and symbolic forms.

**Use when you need to: convert chmod mode · apply symbolic chmod clauses · octal to symbolic permissions.**

## Decide before calling

Read the [versioned contract](/v1/tools/chmod-mode-convert/versions/1.0.0) and the supported scope below. Reuse `chmod-mode-convert@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `chmod-mode-convert@1.0.0` for convert chmod mode. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- convert chmod mode
- apply symbolic chmod clauses
- octal to symbolic permissions
- symbolic permissions to octal
- calculate chmod result
- evaluate Unix file mode

## Not supported

- applying permissions to a filesystem object
- ACLs, umask-dependent omitted-who clauses, or platform-specific permission extensions

## Behavior

- mode is either exactly four octal digits (special, user, group, other) or exactly nine rwx characters; symbolic s/S and t/T encode special bits.
- clauses is optional and defaults to no changes; otherwise it is a comma-separated sequence with explicit u/g/o/a, one of +-=, and one or more rwxXst or u/g/o copy letters.
- Clauses run left to right. Copy and X inspect the mode at the start of their clause; X adds execute only for a directory or when any execute bit is already set.
- An omitted who is rejected so no platform-dependent umask participates; s affects selected u/g classes and t affects selected o (including a).

## Input

- `mode` (string, required): min length 4; max length 9
- `clauses` (string, optional): min length 3; max length 256
- `is_directory` (boolean, optional): default `false`

## Output

- `octal` (string, required): pattern `^[0-7]{4}$`
- `symbolic` (string, required): min length 9; max length 9

## Limits

- max mode bytes: 9
- max clauses bytes: 256
- max clauses: 32

## Example

Request input:

```json
{
  "mode": "0644",
  "clauses": "u+x,g+w"
}
```

Response:

```json
{
  "result": {
    "octal": "0764",
    "symbolic": "rwxrw-r--"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "chmod-mode-convert",
  "version": "1.0.0",
  "input": {
    "mode": "0644",
    "clauses": "u+x,g+w"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/chmod-mode-convert/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"mode":"0644","clauses":"u+x,g+w"}'
```

The machine-readable contract is at [/v1/tools/chmod-mode-convert/versions/1.0.0](/v1/tools/chmod-mode-convert/versions/1.0.0).

### CLI

```sh
node cli.mjs run chmod-mode-convert 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

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