CLI Reference

merql ships with a CLI at bin/merql for capturing snapshots, computing diffs, and running merges directly from the terminal.

Quick start

Shell

# Set up your database connection.
export MERQL_DB_DSN="sqlite:/path/to/db.sqlite"

# Capture a baseline.
./bin/merql snapshot base

# Make some changes, then capture again.
./bin/merql snapshot current

# See what changed.
./bin/merql diff base current

# Three-way merge with dry-run preview.
./bin/merql merge base ours theirs --dry-run

Environment variables

The CLI reads database connection details from environment variables. You can connect using either a PDO DSN string or individual MySQL parameters.

DSN-based connection

Use MERQL_DB_DSN for PDO-backed connections. This is the recommended approach for SQLite and for non-standard configurations.

Variable	Description	Example
`MERQL_DB_DSN`	Full PDO DSN string	`sqlite:/path/to/db.sqlite`
`MERQL_DB_USER`	Username (optional with DSN)	`root`
`MERQL_DB_PASS`	Password (optional with DSN)	`secret`

Shell

# SQLite file.
export MERQL_DB_DSN="sqlite:/var/data/myapp.sqlite"

# SQLite in-memory.
export MERQL_DB_DSN="sqlite::memory:"

# MySQL via DSN.
export MERQL_DB_DSN="mysql:host=127.0.0.1;dbname=mydb;charset=utf8mb4"
export MERQL_DB_USER="root"
export MERQL_DB_PASS="secret"

MySQL shorthand

When MERQL_DB_DSN is not set, the CLI falls back to MySQL-specific variables.

Variable	Default	Description
`MERQL_DB_NAME`	(required)	Database name
`MERQL_DB_HOST`	`127.0.0.1`	MySQL host
`MERQL_DB_PORT`	`3306`	MySQL port
`MERQL_DB_USER`	`root`	MySQL username
`MERQL_DB_PASS`	(empty)	MySQL password
`MERQL_DB_ADAPTER`	`pdo`	Set to `mysqli` to use the mysqli adapter

Shell

export MERQL_DB_NAME="wordpress"
export MERQL_DB_HOST="127.0.0.1"
export MERQL_DB_PORT="3306"
export MERQL_DB_USER="root"
export MERQL_DB_PASS="password"

Commands

`merql snapshot <name>`

Capture the current database state and save it as a named snapshot.

Shell

./bin/merql snapshot baseline

Output:

Code

Snapshot 'baseline' saved
Tables: posts, comments, users, settings

Snapshots are persisted as JSON files in .merql/snapshots/ by default. The name must contain only alphanumeric characters, dashes, and underscores.

Typical workflow: capture a snapshot before making changes, then capture another after. The two snapshots form the basis of a diff or merge.

`merql diff <base> <current>`

Compare two named snapshots and display a summary of differences.

Shell

./bin/merql diff baseline current

Output:

Code

Changeset: baseline -> current
  Inserts: 3
  Updates: 7
  Deletes: 1

Both snapshots must already exist (previously captured with merql snapshot). The diff does not require a database connection since it operates on saved snapshot files.

`merql merge <base> <ours> <theirs>`

Perform a three-way merge of three named snapshots.

Shell

./bin/merql merge base ours theirs

Output:

Code

Merge: base + ours + theirs
  Operations: 12
  Conflicts:  0
  Clean:      yes

All three snapshots must already exist. The merge does not require a database connection since it operates on saved snapshot files.

`--dry-run`

Add the --dry-run flag to preview the SQL statements that the merge would generate, without executing anything.

Shell

./bin/merql merge base ours theirs --dry-run

Output:

Code

Merge: base + ours + theirs
  Operations: 3
  Conflicts:  0
  Clean:      yes

Dry run SQL:
  INSERT INTO `posts` (`id`, `title`, `status`) VALUES ('10', 'New Post', 'draft');
  UPDATE `posts` SET `title` = 'Updated Title' WHERE `id` = '5';
  DELETE FROM `comments` WHERE `id` = '3';

Testing commands

merql includes additional CLI tools for its oracle-driven test suite. These are used during development to verify merge correctness.

Command	Description
`./bin/oracle <name>`	Compute expected merge result for a scenario
`./bin/actual <name>`	Run merql on a scenario and capture output
`./bin/compare <name>`	Diff oracle vs actual output
`./bin/test-scenario <name>`	Full pipeline: setup, oracle, actual, compare
`./bin/test-regression`	Run all scenarios
`./bin/test-regression --jobs 4`	Run scenarios in parallel
`./bin/test-regression --category merge`	Run scenarios by category
`./bin/test-regression --fast`	Pass/fail only, no reports
`./bin/verify-compliance`	Full compliance report
`./bin/verify-all`	PHPStan + code style + PHPUnit + oracle regression

Snapshot storage

By default, snapshots are stored in .merql/snapshots/ relative to the working directory. Each snapshot is a single JSON file named <name>.json.

To change the storage directory, set it in PHP before using the CLI (or modify the CLI script):

PHP

use Merql\Snapshot\SnapshotStore;

SnapshotStore::setDirectory('/var/data/merql-snapshots');

Snapshot files are portable. You can copy them between machines, commit them to version control, or share them for collaborative debugging.