Update

Tool Name: files/update

Edits part of an EXISTING file in place: appends text or replaces an inclusive line range. Mutating and not atomic; the file keeps its mode and owner. To write a whole file use files/create; to see the lines first use files/read with start_line/end_line. With append: true exactly content is added at the end (no newline is added, include your own) and the file is created if missing, though not its parent directories; append wins over any line range. Otherwise start_line AND end_line are both required (1-indexed, end_line >= start_line), the file must exist, and those lines are replaced by content (one trailing newline of content is ignored; an end_line past the end is clamped; a start_line past the end adds content as a new last line). There is no insert or delete mode: replacing with empty content leaves one empty line. Returns Successfully appended to PATH or Successfully updated lines A-B in PATH, no diff. path must be absolute; privileged: true (a grant, and for root a paths: entry) edits files you cannot write.

Arguments

Argument	Type	Required	Description
`content`	string	yes	Text to append, or to replace the line range with (no newline is added when appending)
`path`	string	yes	Absolute path of the file to edit
`append`	boolean	no	If true, append content at the end (creates the file if missing); takes precedence over start_line/end_line
`end_line`	integer	no	Last line to replace (inclusive, >= start_line; past the end of the file is clamped)
`privileged`	boolean	no	Run as root. Needs a grant for this tool in mcp-sudo.yaml and a `paths:` entry covering the path, otherwise refused
`start_line`	integer	no	First line to replace (1-indexed); required together with end_line unless append is true

Example

Every example below shows the equivalent linuxctl command and the raw MCP JSON-RPC call it resolves to. The raw call always follows the same two-step pattern (see MCP API overview for the full explanation): open an SSE stream to get a one-time POST endpoint, then POST the JSON-RPC request there - the result streams back on the SSE connection.

linuxctl

linuxctl update files /tmp/note.txt --content " world" --append true

Output:

Successfully appended to /tmp/note.txt

curl (raw MCP JSON-RPC)

# 1. Open the SSE stream (in the background) and capture the one-time POST endpoint
curl -N -s --cacert mcpd.crt -H "Authorization: Bearer $MCP_TOKEN" https://localhost:9091/sse &
# server sends: event: endpoint / data: /message?session_id=...

# 2. POST the tools/call request to that endpoint
curl -s --cacert mcpd.crt -X POST "https://localhost:9091/message?session_id=<from step 1>" \
  -H "Authorization: Bearer $MCP_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc": "2.0", "id": "1", "method": "tools/call", "params": {"name": "files/update", "arguments": {"path": "/tmp/note.txt", "content": " world", "append": true}}}'

# 3. The result arrives on the SSE stream opened in step 1

Response:

{
  "jsonrpc": "2.0",
  "id": "c2",
  "result": {
    "content": [
      {
        "type": "text",
        "text": "Successfully appended to /tmp/note.txt"
      }
    ]
  }
}

Arguments​

Example​

Arguments

Example