Post-scripts¶

Operate your own script when a download finishes, with unshackle's metadata passed in as {variable} placeholders. Use it to hand a finished file to an uploader, send a notification, or start a library scan.

`post_scripts`¶

Type: list[dict] · Default: [] (unshackle operates no scripts)

unshackle.yaml

post_scripts:
  - command: "python /opt/upload.py {filepath} --service={service} --season={season} --episode={episode} --tmdb={tmdb} --subs={sidecars}"
    event: success # success | failure
    mode: file # file | season | run
  - command: "python /opt/notify.py --title={title} --episode={episode}"

Every entry that matches the event and mode runs, so one download can feed an uploader and a notifier without a wrapper script. You can also write an entry as a plain string, which is the same as {command: "...", event: success, mode: file}.

Key	Default	Meaning
`command`	required	The command to run, with `{variable}` placeholders
`event`	`success`	`success` when a file was written, `failure` when the download failed
`mode`	`file`	`file`, `season`, or `run`. See Modes
`wait`	`false`	`true` makes unshackle wait for the script to exit before carrying on. See Waiting for a script

unshackle skips an entry whose event or mode is not one of the listed values, and logs a warning that names the bad value, once per command. unshackle also skips an entry whose command it cannot split into arguments, such as one with an unbalanced quote, and logs a warning. Neither stops the download or the other entries.

How the command runs¶

unshackle splits the command into arguments first, and then substitutes the variables into those arguments. The process runs without a shell.

This is what keeps a title like Bob"; rm -rf ~ harmless: a value can never turn into an extra argument or a shell operator, and you never have to think about quoting. It also means a path containing spaces always arrives as a single argument on every OS.

Prefix your variables

Titles, episode names and IDs come from the streaming service, not from you. Tokenizing first stops a value becoming a new argument, but a value on its own can still be a whole argument. A bare {title} whose value is --upload-file=/etc/passwd would arrive as an option to your script, not as text. Write --title={title}, not a bare {title}, so a service can never forge a flag. unshackle refuses to operate a command when a substituted value would become an option-like token (one that starts with -), and logs a warning instead.

No shell features, and name your interpreter

Pipes, &&, > redirection, ~ and globs do not work, because unshackle uses no shell. If you want them, make the shell explicit: bash -c "...".

For the same reason there is no interpreter lookup. Write python /opt/upload.py rather than /opt/upload.py. unshackle will not guess whether you meant the system Python or the one in its own virtual environment.

On Windows, when a fixed part of an argument contains a space, quote the whole argument ("--out=C:\My Dir\{filename}"), not only the value. Substituted values never need quoting on any OS.

On Windows, do not target a .bat or .cmd file directly. Windows runs batch files through cmd.exe, whose argument quoting differs from every other program and has a history of letting a crafted value break out (CVE-2024-3566). Call the interpreter and pass the script as an argument (python upload.py, pwsh -File upload.ps1) instead.

By default, scripts are fire and forget. unshackle starts the process, writes the command to the debug log, and carries on. It does not wait for the script, capture its output, time it out, or change its own exit code when a script fails. A script keeps running if unshackle exits first, and Ctrl+C during a season pack does not kill the scripts already started.

One process per file

In file mode a large season pack starts one process per episode with nothing throttling them. If your script is heavy, set wait: true, queue the work inside the script, or use mode: season.

Waiting for a script¶

unshackle.yaml

post_scripts:
  - command: "python /opt/upload.py --file={filepath}"
    wait: true

With wait: true, unshackle waits until the script exits, then writes the exit code to the debug log and carries on. Because the file post-script runs between titles, unshackle runs one script at a time over a season pack instead of starting them all at once. unshackle only logs the exit code: a failing script does not fail the download or change unshackle's own exit code. --postscript entries never wait.

Variables¶

Metadata comes from the same naming context that produced the file's name, built per output file. So {quality} and {hdr} always give the values for the file unshackle passes in. Downloading -q 1080,2160 -r HDR10,SDR produces four files, each with its own invocation and its own values.

Variable	Value
`{filepath}`	Absolute path of the output file
`{filename}`	Its filename, with extension
`{folder}`	Absolute path of its parent folder
`{ext}`	Its extension, including the dot
`{sidecars}`	Sidecar subtitle files written for this output, newline separated
`{title}`	Show, movie or track name, sanitized
`{title_raw}`	Exactly what the service returned, untouched
`{title_id}`	The service's ID for the title
`{service}`	Service tag
`{year}` `{season}` `{episode}` `{episode_name}`	Season and episode are plain numbers (`1`, `5`)
`{quality}` `{resolution}` `{hdr}` `{hfr}` `{vcodec}` `{acodec}` `{edition}` `{tag}` `{lang_tag}`	As in the filename template, for this file
`{tmdb}` `{imdb}` `{tvdb}`	The tagging IDs in use, otherwise empty. See Tagging IDs
`{error}`	Failure message. Empty on success

Every variable from your output_template is available here as well, including {video} and {audio}, of which {vcodec} and {acodec} are aliases.

Empty variables become an empty string

--tmdb={tmdb} with no ID resolved hands your script --tmdb=, so treat an empty string as absent. Write your script to accept an empty value for every variable.

Empty is common, and not only when data is missing:

No metadata provider found an ID. {tmdb} is empty when no metadata provider found the title, the matching API key is missing, or the title is a movie you gave no ID for.
The title has no such field. Movies have no {season} or {episode}, and music has neither.
The naming context renders it empty on purpose. {hdr} is empty for an SDR file, because SDR is the absence of an HDR tag in a filename rather than a tag that reads SDR. {edition}, {atmos}, {multi}, {dual} and {hfr} behave the same way. If your script needs the word SDR, derive it from an empty {hdr} yourself.
The post-script is a failure one. A failed download has no output file to read metadata from, so everything that comes from the naming context is empty. See Events.

There is no {variable?} conditional here, unlike output_template. The token is always passed, so the argument list your script receives keeps the same shape on every run and your argument parser does not have to cope with a flag appearing and disappearing.

Season and episode are the plain numbers, not the S01E05 form used in filenames. The padding and the separator belong to the filename template rather than to the data.

Music variables¶

A music download builds its variables from the music naming context, so a post-script gets the release fields instead of the season and episode ones. {season}, {episode} and {episode_name} are always empty for music.

Variable	Value
`{artist}`	Track artist
`{album_artist}`	Album artist, falling back to the track artist
`{album}`	Album name
`{track_number}` `{disc}`	Zero padded. `{disc}` is empty on a single-disc release
`{track_total}` `{disc_total}`	Zero padded totals, empty when the service did not give them
`{isrc}` `{upc}` `{label}` `{genre}`	As the service reported them, empty when absent
`{release_type}`	`album`, `single`, `ep`, and so on. A service that reports nothing gives `album`
`{explicit}`	The word `Explicit` when the track is flagged, otherwise empty

In a file post-script {title} is the track name. See Modes for what an album post-script puts in {title}.

{year} is empty when the service gives the release no year. {ext} is the container the track arrived in, such as .flac, because a music download is not muxed.

Tagging IDs¶

{tmdb}, {imdb} and {tvdb} carry the IDs unshackle tags the file with. unshackle reads them at the moment it dispatches the post-script, and not at the start of the run. The title search inside the download loop finds an episode's TMDB ID, so a post-script fires with it already filled in.

They hold an ID you passed with --tmdb, --imdb or --tvdb, plus a TMDB ID the episode search resolved. No such search runs for a movie, so a movie post-script gets them empty unless you passed one.

Sidecar files¶

{sidecars} holds the sidecar subtitle files written beside the output, which are the only extra files a download leaves next to it. unshackle muxes attachments such as fonts into the container and deletes temporary artwork, so neither appears. Expect {sidecars} to be empty unless subtitle.output_mode is sidecar or both, which is not the default. A music download writes no sidecars at all.

Paths are absolute and separated by a newline, because a newline is the only character that cannot appear in a filename on any supported OS. The whole list arrives as a single argument, so your template needs no quoting.

When one download writes several outputs (-q 1080,720), each output's folder gets its own copy of the sidecar files, and each invocation lists the copies sitting beside its own {filepath}.

Reading {sidecars} in Python

subs = [p for p in sys.argv[i].removeprefix("--subs=").split("\n") if p]

Modes¶

`mode`	Runs	`{filepath}`	`{sidecars}`
`file`	Once per output file	That file	That output's sidecars
`season`	Once per season folder, after that season's last queued title	Empty	Empty
`run`	Once per folder written, at the end of the run	Empty	Empty

season means everything this run asked for

A season post-script fires when the last title this run queued for that season finishes. With -w S01-S02 the S01 post-script runs while S02 is still downloading. It says nothing about whether the season is complete on disk. Downloading a single episode fires the post-script for that season as soon as the episode lands.

A title that fails stops the whole run. unshackle dispatches the failure post-script for that title and then returns. It downloads no further title, and no season or run post-script fires after that point. This applies to every title type. If one episode of S01 fails, the S01 post-script does not fire at all.

unshackle attaches the post-script to the folder, not to the season, so one season landing in several folders (-q 1080,720 with a quality-dependent folder template) fires it once per folder, each with its own {folder}. A movie is a group of its own: a season post-script fires for a movie's folder as soon as the movie finishes.

In run mode every variable except {folder} is empty, because one run can cover several shows. Only {folder} is meaningful, which makes it useful for starting a library scan once.

Music¶

Music uses the same three modes, with the album standing in for the season.

`mode`	Runs
`file`	Once per track, after its metadata has been written
`season`	Once per album folder, after every queued track of that album has landed
`run`	Once per folder written, at the end of the run

In a file post-script {title} and {title_raw} are the track name. In an album post-script they are the album name, and the per-track variables {track_number}, {disc} and {isrc} are empty, in the same way that {episode} is empty in a season post-script.

An album post-script obeys the same rule as a season post-script. It fires when the last track this run queued for that album lands. This does not mean that the album is complete on disk. A one-track download fires the album post-script as soon as that track lands. If a track fails, the run stops there, so the album post-script never fires, in the same way as an episode and its season.

Events¶

success runs after the file has moved to its final path. failure runs when the download fails, with {filepath} empty and {error} set. Each track of an album is its own title. A music failure post-script therefore describes the track that failed, not the release.

failure only fires in file mode

A failure entry with mode: season or mode: run never runs. Leave mode at its default on a failure entry.

A failure post-script has no output file to read metadata from, so it carries only what the title object already knew: {title}, {title_raw}, {title_id}, {year}, {season}, {episode}, {episode_name}, {service}, the tagging IDs and {error}. Everything that comes from the naming context, such as {quality}, {hdr}, {artist} and {album}, is empty.

A resumed --continue-downloads download that finishes runs success as usual. unshackle sees your script's exit code only when that entry sets wait: true, and even then it only writes the code to the debug log. Nothing else reports a failing script. Your script owns its own error handling and logging.

A success post-script always names a file this run wrote. There is no skip-if-exists path in dl today, so nothing fires for a title that was not downloaded.

`--postscript`¶

dl accepts --postscript "<command>", repeatable. Every command given this way runs with event: success and mode: file.

$ unshackle dl --postscript "python /opt/upload.py {filepath}" SERVICE TITLE_ID

It replaces the post_scripts config for that run rather than adding to it, so no configured entry runs while it is in use. That includes your season, run and failure entries, which have no --postscript equivalent.

The REST API¶

The API never accepts a post-script command. postscript, post_script and post_scripts in a POST /api/download body get 400 INVALID_PARAMETERS. A command that arrives from an HTTP caller would be remote code execution.

unshackle does operate the scripts defined in unshackle.yaml for API jobs, music jobs included. Only the command itself may not cross the network.

Logging¶

unshackle logs the command it operated twice: at DEBUG level on the console, and as a post_script_dispatch entry in the structured JSON debug log when that log is on.

unshackle masks both the same way, and honours redact_paths, which is on by default. Debug logs get shared in issue reports, and a post-script command line is mostly paths. URL credentials and token= / api_key= query parameters are also masked.

Do not hardcode secrets in the command

unshackle cannot recognise an arbitrary secret in the command line, such as -H "Authorization: Bearer <key>", and logs it verbatim. Read the secret from a file or an environment variable inside your script rather than putting it in the command.

Limitations¶

No success post-script operates under --no-mux or --skip-dl, because neither writes a muxed output. A failure post-script still runs under --no-mux if the download itself fails.
failure post-scripts only operate in file mode.
There is no webhook sender. Call curl from a script instead.
Script output is not captured. Redirect it inside your own script if you want a log.