sido-askpass

SUDO_ASKPASS shim for tmux, Herdr, coding agents, and other environments without a usable TTY.

When sudo uses askpass, sido-askpass opens a hidden password prompt and returns the password to sudo. Passwords never touch a regular file.

sido is written in Go and ships as a single native binary per platform (Linux x86_64 and macOS arm64), distributed through npm. The sido and sido-askpass executables are tiny POSIX sh launchers that pick the right binary for your OS; sido-askpass is just an alias for sido askpass. No Node.js or bash is required at runtime.

Works with:

• Linux — hidden GUI or terminal password prompts
• macOS — hidden native password dialog
• Codex automatic review — approved retries can authenticate outside the sandbox
• Codex Full Access — sudo authentication from agent-run commands
• tmux — hidden popup prompt without stealing the agent's TTY
• Herdr — temporary password prompt pane that closes automatically
• Raw terminals — /dev/tty fallback when an interactive shell owns the TTY
• Watch mode — approve from a second terminal when a TUI/agent owns the TTY (e.g. ssh → coding agent → sudo with no tmux/Herdr)

Supports Linux (x86_64) and macOS (arm64). Distributed as native binaries — no Node.js or bash at runtime. tmux/Herdr/GUI prompting requires the respective external tool (tmux, herdr, or zenity/kdialog); the /dev/tty and watch backends need only a POSIX shell (for the launcher). Windows is not supported.

Quick start

The package installs two executable names: sido is the command-line interface, while sido-askpass is reserved for the askpass protocol (it is an alias for sido askpass and treats its first argument as a prompt). Both are shell launchers that exec the platform binary (sido-mac / sido-linux).

User setup (recommended)

Install the command, add SUDO_ASKPASS to ~/.profile, and load it into the current shell:

npm install -g sido-askpass && sido install --user

User setup selects the startup file from $SHELL: ~/.zshrc for zsh, ~/.bashrc for Bash, and ~/.profile for other shells. The managed entry is appended after existing shell setup so tools such as fnm are initialized first. Existing sido-managed entries in other supported startup files are migrated to the selected file. For zsh, the managed block also adds alias sudo='sudo -A', making askpass the default for interactive commands. Unmanaged SUDO_ASKPASS entries are preserved.

Restart the shell after installation, or activate the current session with the exact export SUDO_ASKPASS=... command printed by the installer. Shell startup configuration covers interactive shell sessions; GUI applications launched without that shell environment may not inherit SUDO_ASKPASS.

System setup

Install the command and configure Path askpass in /etc/sudo.conf:

npm install -g sido-askpass && sido install --system

System setup runs sudo tee to update /etc/sudo.conf, so the installation command itself must be run somewhere sudo can authenticate.

After first setup, rerun the detected managed user and/or system installation without remembering its scope:

sido install

If no managed installation exists yet, install requires an explicit --user or --system.

To use sido for one command without changing your profile or sudo configuration:

sido run -- sudo -A <command>

Everything after -- is run directly without shell parsing. run sets SUDO_ASKPASS but does not add -A or otherwise rewrite the command, so pass -A explicitly when sudo must use askpass even if a TTY is available. Select an exact prompt adapter for the command with:

sido run --adapter watch -- sudo -A <command>

Using sudo

For the most reliable behavior, explicitly tell sudo to use askpass:

sudo -A <command>

On modern sudo installations, plain sudo commonly falls back to askpass when there is no usable TTY. This automatic fallback has been verified on Fedora:

sudo <command>

TTY allocation is the important distinction:

• Without a TTY, plain sudo can automatically use the configured askpass helper.
• With a real or pseudo-TTY, plain sudo prompts on that terminal instead and does not call askpass.
• Some coding agents start background commands with a pseudo-TTY, so automatic fallback cannot be assumed even when the agent UI has no visible terminal.
• sudo -A requests askpass regardless of whether a TTY exists.

The zsh user installer adds this alias to its managed block, making askpass the default for interactive commands:

alias sudo='sudo -A'

Shell aliases usually do not affect commands launched directly by coding agents or other non-interactive processes. Bash and other shell installations do not add the alias. sido-askpass does not rewrite sudo commands or add -A outside the zsh alias.

Codex test matrix

| Platform and terminal | Codex permissions | Prompt backend | Command | Result | Notes | | ---------------------------- | ----------------- | -------------- | -------------- | ----------- | ------------------------------------------------------------------------------------------------------------------------------------- | | Linux, tmux 3.7b | Automatic review | tmux popup | sudo -A | Tested | The sandbox cannot reach tmux; the approved retry outside the sandbox succeeds. | | Linux, Herdr 0.7.5 | Automatic review | Herdr pane | sudo -A | Tested | The sandbox cannot reach Herdr; the approved retry outside the sandbox succeeds. | | Fedora 44, raw Wayland shell | Automatic review | Zenity 4.2.2 | sudo -A true | Tested | 2026-07-30, sudo 1.9.17p2; no tmux, Herdr, or stdin TTY. | | Linux, any terminal | Full Access | First matching | sudo -A | Supported | sudo and the selected prompt backend can run outside the sandbox. | | Linux, any terminal | Workspace-write | None | Any sudo | Unsupported | no_new_privileges blocks sudo; changing the askpass backend cannot bypass this. | | Linux, pseudo-TTY command | Any sudo-capable | Askpass | Plain sudo | Skipped | sudo uses the allocated TTY instead of askpass; use sudo -A to force askpass. | | Linux, raw terminal | Automatic review | /dev/tty | sudo -A | Untested | No tmux, Herdr, DISPLAY, or Wayland; requires an accessible controlling terminal. | | Linux, pi (no TTY, GUI) | Automatic review | Zenity | Plain sudo | Tested | 2026-07-30, sudo 1.9.17p2: no tmux, Herdr, or TTY; DISPLAY+zenity available. Plain sudo auto-fell back to askpass. | | macOS | Any | AppleScript | sudo -A | Untested | The dialog backend exists, but Codex sandbox and approval behavior has not been tested. |

Codex automatic approval review does not widen the sandbox itself. It is useful because it can approve an eligible retry outside the sandbox. Full Access also works, but grants Codex substantially broader system access.

When a sandboxed Linux Codex process cannot reach tmux, sido-askpass exits immediately instead of hanging and prints:

[sido] tmux access denied; retry the sudo command with escalated permissions

This gives Codex an actionable reason to retry with escalated permission.

Other clients

| Client | Compatibility | Notes | | -------- | ------------- | --------------------------------------------------------------------------------------------------------------------------- | | Pi | Tested | No TTY — plain sudo auto-falls back to askpass; zenity GUI prompt. 2026-07-30, Fedora 44, sudo 1.9.17p2. | | OpenCode | Tested | 2026-07-30, Fedora 44, /dev/tty fallback, sudo -A whoami → root. |

Prompt backend compatibility

By default, SIDO_ADAPTER=auto uses the first matching context:

| Context | Prompt method | Status | | ---------------------------- | --------------------------------------------------- | ----------------------- | | $TMUX set | tmux popup with a hidden native read; FIFO return | Tested on Linux | | $HERDR_ENV=1 | Temporary Herdr pane with a hidden native read | Tested on Linux | | macOS | Hidden osascript dialog | Implemented, unverified | | Linux + $DISPLAY / Wayland | zenity, then kdialog | Tested on Linux | | Canonical /dev/tty | Hidden native read on /dev/tty | Fallback | | Raw/no TTY | Watch mode: park request + FIFO, approve | New |

Set SIDO_ADAPTER to bypass detection and require one exact adapter:

| Adapter | Behavior | | ----------- | ----------------------------------------------------- | | auto | Use the detection chain above; this is the default | | tmux | Open a hidden prompt in a tmux popup | | herdr | Open a hidden prompt in a temporary Herdr pane | | osascript | Open the native macOS password dialog; requires macOS | | zenity | Open a Zenity password dialog | | kdialog | Open a KDE password dialog | | tty | Read a hidden password from /dev/tty | | watch | Wait for sido approve from another terminal |

An explicitly selected adapter either succeeds or exits with an error. It never falls back to another adapter. run accepts the same selection as --adapter <name>:

SIDO_ADAPTER=osascript sudo -A <command>
sido run --adapter tty -- sudo -A <command>

The prompt also shows the requesting command when the parent process command line is available. If process inspection is blocked, it silently shows the normal password prompt without the command. The displayed command includes its arguments, which may reveal sensitive arguments to anyone who can see the prompt.

Watch mode

When no inline prompt is safe — a coding agent's TUI owns the TTY in raw mode, or there is no TTY at all — sido-askpass parks the request and waits for a password from a second terminal:

sido approve   # approve the most recent pending request (one-shot)
sido watch     # approve requests as they arrive (Ctrl-C to exit)

The original terminal prints a hint telling you which command to run. Requests live under $XDG_RUNTIME_DIR/sido (or ~/.cache/sido); the password travels through a kernel FIFO, never a file. SIDO_ADAPTER=watch selects watch mode; SIDO_WATCH_TIMEOUT=<sec> sets how long it waits before giving up (default 120).

Status and removal

Upgrade an npm installation to the latest version and refresh the user configuration:

sido upgrade
sido update          # alias for upgrade

The upgrade command currently supports npm global installations only and rejects commands installed by another package manager. It checks the latest published version, upgrades only when that version is newer (or always with --force), then runs sido install to refresh the existing managed configuration. If npm fails, existing configuration is left unchanged.

Inspect the active environment and installed configuration:

sido status
sido status --user
sido status --system

Remove either setup:

sido uninstall --user
sido uninstall --system

--user and --system are mutually exclusive for install, uninstall, and status. Omitting both is supported only by status.

Security

Password input is hidden. tmux, Herdr, and watch mode return the password through a kernel FIFO; GUI and TTY backends return it through process stdout. Each tmux, Herdr, or watch prompt uses a private directory (mode 0700 under $XDG_RUNTIME_DIR/sido for watch) with a mode-0600 FIFO. Its FIFO and prompt are accessible only to the current user and are removed when prompting ends. Watch's approver feeds the password through the FIFO over stdin, never argv, so it never appears in ps. The prompt file contains the displayed command and prompt, but never the password.