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Exit Codes

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Interpret process exit codes, classify failures, and handle interruptions or mixed batch results in scripts.

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comic-dl uses standard process exit codes to communicate results to scripts and CI systems.

Exit code reference

Code Constant Meaning
0 EXIT_OK Success. Nothing reported as error.
1 EXIT_ERROR Runtime error. A download, library, or network step failed.
2 EXIT_USAGE Invalid CLI usage. Bad flag, bad value, unknown command.
130 EXIT_INTERRUPTED Interrupted by Ctrl-C, SIGINT, or SIGTERM.

Use the named constants — never bare integers — in any code that checks exit status.

Error kinds

Every comic_dl.errors.ComicError carries a stable machine-readable kind alongside its message and exit code, exposed by comic_dl.ui.error_kind. Branch on kinds instead of parsing message text.

Kind Exception Meaning
usage ValidationError Invalid input or usage (exit 2).
scrape ScrapeError Page-level scrape failure (no images, auth wall).
download DownloadError Runtime download failure.
timeout ScrapeTimeout, DownloadTimeout Hard timeout exceeded.
library LibraryError Library database or operation failure.
network — (curl_cffi, builtin ConnectionError) Connectivity problem.
os — (builtin OSError) Filesystem or OS-level failure.
internal anything else Unexpected internal error.

When each code applies

Exit 0

  • All URLs downloaded successfully (or skipped as already-downloaded).
  • Library commands (list, info, latest) complete without error.
  • --dry-run completes without error.
  • --list-sources completes.
  • config validate finds no problems.

Exit 1

  • One or more URLs failed to download (network error, server error, gallery unavailable).
  • A library operation fails after the target series is resolved (disk error, database error).
  • An estimate exceeds --max-size.
  • config validate finds problems.

Exit 2

  • Unknown flag or command.
  • Invalid flag value (e.g. --concurrency 0).
  • --chapters contains invalid syntax.
  • info, remove, restore, update cannot resolve the target series (no match, or ambiguous with candidates shown).
  • Bad -o path (doesn’t exist, isn’t a directory, or isn’t writable).

Exit 130

  • User pressed Ctrl-C once (graceful stop at next item boundary).
  • User pressed Ctrl-C twice within 2 seconds (force quit).
  • SIGTERM received.
  • A confirmation was required but could not be answered: --force with a multi-URL run in non-interactive mode when re-downloads would occur, library remove --json without -y, or EOF on an interactive prompt.

Interrupt behavior

Ctrl-C (SIGINT) and SIGTERM use a two-stage cooperative model:

  1. First press — stops at the next item boundary (chapter or URL). The current download finishes, partial .part files are kept, and the process exits 130. A resume hint echoes the command you ran.
  2. Second press within 2 seconds — force-exits immediately via os._exit(130).

A second press after the 2-second grace window resets the timer.

Batch processing

When downloading from a file (-f), each URL is processed independently. If some fail and some succeed, the exit code is 1. A summary is printed at the end showing succeeded, skipped, and failed counts. For structured results, see JSON output.