Identity

Binary: sqlite3
No service: SQLite is embedded — there is no daemon, no port, no systemd unit
Database: a single file on disk (e.g. /var/lib/myapp/data.db)
Distro install: apt install sqlite3 / dnf install sqlite

Key Operations

Operation	Command
Open a database file	`sqlite3 /path/to/db.sqlite3`
Help (dot-command list)	`.help`
List tables	`.tables`
Show CREATE statements	`.schema` or `.schema <table>`
Show column info	`PRAGMA table_info(<table>);`
Column-aligned output	`.mode column`
Table-style output	`.mode table`
JSON output	`.mode json`
CSV output	`.mode csv`
Show column headers	`.headers on`
SELECT example	`SELECT * FROM users WHERE id = 1;`
INSERT example	`INSERT INTO users (name, email) VALUES ('Alice', 'a@example.com');`
UPDATE example	`UPDATE users SET email = 'b@example.com' WHERE id = 1;`
DELETE example	`DELETE FROM users WHERE id = 1;`
Export entire DB as SQL	`.dump` (stdout) or `.output dump.sql` then `.dump`
Import SQL file	`.read /path/to/dump.sql`
Import CSV into table	`.import --csv /path/to/file.csv tablename`
Reclaim deleted space	`VACUUM;`
Integrity check	`PRAGMA integrity_check;`
Journal mode	`PRAGMA journal_mode;` / `PRAGMA journal_mode = WAL;`
Page size	`PRAGMA page_size;`
Attach a second DB	`ATTACH '/path/other.db' AS other;`
Online backup	`.backup /path/to/backup.db`
Quit	`.quit` or Ctrl-D

Symptom	Likely cause	Check/Fix
`database is locked`	Another writer has an exclusive lock	Only one write connection at a time; switch to WAL mode (`PRAGMA journal_mode = WAL`) for concurrent reads
`disk I/O error`	Bad file permissions, full disk, or corruption	Check `ls -lh`, `df -h`, and `PRAGMA integrity_check`
WAL side-car files left behind	Crash or missing checkpoint	Safe to open — SQLite auto-checkpoints on next open; force with `PRAGMA wal_checkpoint(FULL);`
`no such table`	Wrong database file opened	Verify path with `sqlite3 db.sqlite3 ".tables"`
CSV import encoding errors	Non-UTF-8 source file	Convert with `iconv -f latin1 -t utf-8 file.csv > file_utf8.csv` then re-import
Slow queries on large database	Missing index	`EXPLAIN QUERY PLAN SELECT ...;` — look for `SCAN TABLE` instead of `SEARCH TABLE USING INDEX`
`unable to open database file`	Path does not exist or directory not writable	`ls -ld $(dirname /path/to/db.sqlite3)` — parent directory must be writable

Single writer: SQLite serializes all writes. Applications with high write concurrency should use WAL mode, or consider a client-server database.
WAL mode: PRAGMA journal_mode = WAL allows concurrent reads and one writer simultaneously. Default (DELETE) mode blocks readers during writes.
No user authentication: Access control is purely filesystem-based. Any OS user with read permission on the file can read the entire database.
VACUUM needed after bulk deletes: SQLite does not shrink the file automatically after large deletes. Run VACUUM; or VACUUM INTO '/path/backup.db' to reclaim space.
Type affinity, not strict typing: SQLite uses type affinity — INSERT INTO t (int_col) VALUES ('abc') succeeds silently unless the table was created with STRICT. This causes surprises when migrating from other databases.
Datetime has no native type: Dates are stored as TEXT (ISO-8601), REAL (Julian day), or INTEGER (Unix timestamp). strftime() and date() functions handle conversion but behavior differs from PostgreSQL/MySQL.
FTS5 is a separate virtual table: Full-text search requires creating a VIRTUAL TABLE ... USING fts5(...) and inserting separately from the main table, or using a content table.

See references/ for:

sqlite-cli.md — task-organized CLI reference: open, inspect, query, export, import, backup, PRAGMA tuning, FTS5, attach
docs.md — official documentation links