The agent's simplest write — `sh "cat > file"` for one-liners

The simplest thing an agent running on the core can do — write a file straight to the workspace with a shell redirect.

You don't need an upload tool to put a file on disk. The sandbox shell can do it directly:

> Write "hello world" to /workspace/greeting.txt.

The agent runs:

sh "echo 'hello world' > /workspace/greeting.txt"

Done. No pre-signed link, no audit row labelled "upload", no R2 event notification — just a regular shell command writing to the FUSE-mounted FS.

When this is the right tool

• One-liners — echo, printf, small heredocs.
• The content fits comfortably in the shell command — no escaping nightmare with shell metacharacters or newlines.
• You don't need a permanent record of "this was an upload" — sh lands in sandbox_invocation, not upload_link.

When to graduate

• The content has shell metacharacters (quotes, backticks, $, embedded newlines). Escaping gets fragile fast. Use upload.write with content_text.
• The content is binary. echo and printf aren't binary-safe. Use upload.write with content_base64, or upload.create_link for anything > 1 MiB.
• The file is bigger than ~16 KiB. sh's command field has practical length limits and a giant cat > foo makes a mess of audit logs.
• You want the upload to show up as an upload in info's recent_uploads or the dashboard's audit panel. sh "cat >" won't.

A note on tee

sh "cat <<EOF | tee /workspace/foo" and sh "tee /workspace/foo <<<'content'" are the same pattern — same tradeoffs apply. Tee is sometimes nicer because it prints what it wrote, which the agent can read back in the same call.

Next steps

• Tiny configs, no curl — upload.write.
• What recent_uploads.status means.

Where this fits

This is the Run your agents pillar of connect0 — the core that connects everything your company runs on. The agent runs on the core and writes directly to the workspace FS with a plain shell command — the lowest-ceremony way to put a file where your agent can act on it. Start building → · All guides →