YAML — Practical Examples

Types in YAML

YAML booleans, nulls, and numbers map naturally to JSON types:

printf 'active: true\ncount: 42\nlabel: null\n' | \
  fimod s --input-format yaml -e 'data' --output-format json

{"active": true, "count": 42, "label": null}

Convert to other formats

# YAML → JSON
printf 'host: localhost\nport: 5432\ndb: myapp\n' | \
  fimod s --input-format yaml -e 'data' --output-format json

# YAML → TOML
printf 'host: localhost\nport: 5432\ndb: myapp\n' | \
  fimod s --input-format yaml -e 'data' --output-format toml

For a file:

cat > /tmp/config.yaml << 'EOF'
host: localhost
port: 5432
db: myapp
EOF

fimod s -i /tmp/config.yaml -e 'data' --output-format json
fimod s -i /tmp/config.yaml -e 'data' -o /tmp/config.toml

TOML requires a root-level object

Arrays or scalars at the root will fail to serialize as TOML — TOML spec constraint.

Normalize / reformat in-place

cat > /tmp/config.yaml << 'EOF'
host:   localhost
port:  5432
db:    myapp
EOF

fimod s -i /tmp/config.yaml -e 'data' --in-place
cat /tmp/config.yaml

host: localhost
port: 5432
db: myapp

Filter a list

printf 'users:\n  - name: Alice\n    role: admin\n  - name: Bob\n    role: user\n' | \
  fimod s --input-format yaml \
  -e '[u for u in data["users"] if u["role"] == "admin"]' \
  --output-format yaml

- name: Alice
  role: admin

Edit a nested value

cat > /tmp/config.yaml << 'EOF'
database:
  host: localhost
  port: 5432
EOF

fimod s -i /tmp/config.yaml -e 'dp_set(data, "database.port", 5433)' --output-format yaml

database:
  host: localhost
  port: 5433

YAML array → CSV

printf '- name: Alice\n  age: 30\n- name: Bob\n  age: 25\n' | \
  fimod s --input-format yaml -e 'data' --output-format csv

name,age
Alice,30
Bob,25