Shell Semantics

This document defines the current V1 shell execution contract.

Current execution model

ota is shell-native in V1.

Current command execution uses:

• Unix-like systems: sh -lc
• Windows: cmd /C

This applies to:

• task run
• task script
• service start
• service stop
• service healthcheck
• configured checks

Working directory

Commands run in the contract directory:

• if a direct ota.yaml path is given, its parent directory is used
• if a directory is given, that directory is used

Environment behavior

Current V1 behavior:

• configured env values are applied to task execution
• required env values must be present or resolvable from defaults where allowed
• ota does not translate shell syntax across platforms

That means shell-specific constructs remain platform-sensitive.

Examples:

• export FOO=bar && cmd is Unix-style
• set FOO=bar && cmd is Windows cmd style

run vs script

Current V1 distinction:

• run: single command string
• script: multiline shell body

Both still execute through the same platform shell model above.

Non-goals in V1

• no per-task shell selection
• no PowerShell-specific execution mode
• no Bash-only contract mode
• no shell portability translation
• no isolated shell environment for ephemeral

Practical implication

Repos should write task and service commands with their supported platforms in mind.

ota guarantees the invocation model. It does not guarantee that shell-specific commands become portable automatically.