---
product: Chilkat
product_version: 11.7.0
language: pascal
language_label: Lazarus Pascal
class: UnixCompress
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/pascal_UnixCompressRef.html
---
# Chilkat UnixCompress — Lazarus Pascal — v11.7.0

> Chilkat 11.7.0 · language=pascal · class=UnixCompress
> Other versions: replace `11.7.0` in this URL. Other languages: `https://www.chilkatsoft.com/ai-docs/v/11.7.0/<lang>/classes/UnixCompress.md`.
> Language-wide rules (install, unlock, error model, strings/bytes): `https://www.chilkatsoft.com/ai-docs/v/11.7.0/pascal/guide.md`.

## Purpose

**Compress, uncompress, and unpack legacy UNIX `.Z` files.**

`Chilkat.UnixCompress` provides UNIX `compress` and `uncompress` functionality for legacy `.Z` files. It supports file-based, memory-based, and string-based workflows, uses LZW compression, can unpack `.tar.Z` archives, and includes abort and progress-related support for longer-running operations.

**Compress to .Z**

Compress files, memory data, or strings into UNIX `.Z` format using LZW compression.

**Uncompress .Z data**

Expand UNIX-compressed data back to files, memory, byte arrays, or text depending on the application workflow.

**File workflows**

Compress and uncompress directly between input and output files when working with existing filesystem data.

**Memory workflows**

Work with compressed or uncompressed byte data in memory when temporary files are not desired.

**String workflows**

Compress and uncompress text using an explicit character set so string data round-trips correctly.

**Unpack tar.Z archives**

Use `UnTarZ` to decompress and extract legacy `.tar.Z` archives in a single workflow.

**Common pattern:** Use `UnixCompress` when the data is in classic UNIX `.Z` format or when a `.tar.Z` archive must be unpacked. Use `Chilkat.Gzip` for `.gz` and `.tar.gz` files, `Chilkat.Bz2` for `.bz2` files, and `Chilkat.Compression` for raw compression algorithms and general-purpose compression workflows.

For an extended overview, see [UnixCompress Class Overview](https://www.chilkatsoft.com/unixcompress_class_overview.asp).

## Object creation, unlocking and error handling

**Create / Free**

```pascal
uses
  Chilkat.UnixCompress;

var
  obj: TUnixCompress;
begin
  obj := TUnixCompress.Create;
  try
    if not obj.IsValid then
      raise Exception.Create('Failed to create a TUnixCompress instance.');

    // ... use obj ...

  finally
    obj.Free;
  end;
end;
```

`constructor Create;`

Allocates the underlying CkUnixCompress object and returns a new TUnixCompress instance. Simply adding **Chilkat.UnixCompress** to the unit's `uses` clause is enough to locate and bind to the Chilkat shared library (DLL / .so / .dylib) at runtime — no separate load step is required. Check `obj.IsValid` after calling `Create`; it is `False` if the underlying library could not be found/loaded or the object could not be allocated (for example, when unlicensed).

`destructor Destroy; override;`

Every TUnixCompress created by calling `Create` should eventually be released by calling `.Free` (inherited from `TObject`). The destructor automatically disposes the underlying CkUnixCompress handle. A native (unmanaged) memory leak occurs if the object is never freed.

Call `Global.UnlockBundle` once at the start of the program, before using this or any other Chilkat class. Any string unlocks a fully functional 30-day trial; a purchased unlock code is used in production. See `guide.md` for the exact code in Lazarus Pascal.

## Members common to every Chilkat class

Documented once per language in `common-members.md`; listed here so this page is self-contained.

| Property | Signature | Access | Meaning |
|---|---|---|---|
| `DebugLogFilePath` | `property DebugLogFilePath: string read GetDebugLogFilePath write SetDebugLogFilePath;` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. |
| `LastErrorHtml` | `property LastErrorHtml: string read GetLastErrorHtml;` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `property LastErrorText: string read GetLastErrorText;` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `property LastErrorXml: string read GetLastErrorXml;` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `property LastMethodSuccess: Boolean read GetLastMethodSuccess write SetLastMethodSuccess;` | read/write | Indicates the success or failure of the most recent method call: `True` means success, `False` means failure. |
| `VerboseLogging` | `property VerboseLogging: Boolean read GetVerboseLogging write SetVerboseLogging;` | read/write | If set to `True`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `property Version: string read GetVersion;` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `AbortCurrent` | property, read/write | `property AbortCurrent: Boolean read GetAbortCurrent write SetAbortCurrent;` |
| `HeartbeatMs` | property, read/write | `property HeartbeatMs: Integer read GetHeartbeatMs write SetHeartbeatMs;` |
| `CompressFile` | method | `function CompressFile(const inFilename: string;     const destPath: string): Boolean;` |
| `CompressStringToFile` | method | `function CompressStringToFile(const inStr: string;     const charset: string;     const destPath: string): Boolean;` |
| `LoadTaskCaller` | method | `// task is a TTask object. function LoadTaskCaller(task: TChilkatBase): Boolean;` |
| `UncompressFile` | method | `function UncompressFile(const inFilename: string;     const destPath: string): Boolean;` |
| `UncompressFileToString` | method | `function UncompressFileToString(const zFilename: string;     const charset: string): string;` |
| `UnTarZ` | method | `function UnTarZ(const zFilename: string;     const destDir: string;     bNoAbsolute: Boolean): Boolean;` |

## Properties

### UnixCompress.AbortCurrent

`Chilkat 11.7.0 · pascal · UnixCompress · AbortCurrent · property · read/write · since 9.5.0.58`

```pascal
property AbortCurrent: Boolean read GetAbortCurrent write SetAbortCurrent;
```

When set to `True`, causes the currently running method to abort. Methods that always finish quickly (i.e.have no length file operations or network communications) are not affected. If no method is running, then this property is automatically reset to `False` when the next method is called. When the abort occurs, this property is reset to `False`. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)

### UnixCompress.HeartbeatMs

`Chilkat 11.7.0 · pascal · UnixCompress · HeartbeatMs · property · read/write`

```pascal
property HeartbeatMs: Integer read GetHeartbeatMs write SetHeartbeatMs;
```

**Full documentation for this property (same in every language):** [Event Callback Examples](https://www.chilkatsoft.com/ai-docs/v/11.7.0/articles/event_callback_examples.md)

The interval in milliseconds between each `AbortCheck` event callback, which enables an application to abort certain method calls before they complete. **By default, HeartbeatMs is set to** `0`**, meaning no AbortCheck event callbacks will trigger.**

## Methods

### UnixCompress.CompressFile

`Chilkat 11.7.0 · pascal · UnixCompress · CompressFile · method`

```pascal
function  CompressFile(const inFilename: string;
    const destPath: string): Boolean;
```

Compresses a file to create a UNIX compressed file (.Z). This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.

Returns True for success, False for failure.

### UnixCompress.CompressStringToFile

`Chilkat 11.7.0 · pascal · UnixCompress · CompressStringToFile · method`

```pascal
function  CompressStringToFile(const inStr: string;
    const charset: string;
    const destPath: string): Boolean;
```

**Full documentation for this method (same in every language):** [List of Valid Charsets](https://www.chilkatsoft.com/ai-docs/v/11.7.0/articles/charsets_supported_by_chilkat.md)

Unix compresses and creates a .Z file from string data. The `charset` specifies the character encoding used for the byte representation of the characters when compressed. The `charset` can be any one of a large number of character encodings, such as `utf-8`, `iso-8859-1`, `Windows-1252`, `ucs-2`, etc.

Returns True for success, False for failure.

### UnixCompress.LoadTaskCaller

`Chilkat 11.7.0 · pascal · UnixCompress · LoadTaskCaller · method · since 9.5.0.80`

```pascal
// task is a TTask object.

function  LoadTaskCaller(task: TChilkatBase): Boolean;
```

Loads the caller of the task's async method.

Returns True for success, False for failure.

### UnixCompress.UncompressFile

`Chilkat 11.7.0 · pascal · UnixCompress · UncompressFile · method`

```pascal
function  UncompressFile(const inFilename: string;
    const destPath: string): Boolean;
```

Uncompresses a .Z file. (This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.)

Returns True for success, False for failure.

### UnixCompress.UncompressFileToString

`Chilkat 11.7.0 · pascal · UnixCompress · UncompressFileToString · method`

```pascal
function  UncompressFileToString(const zFilename: string;
    const charset: string): string;
```

**Full documentation for this method (same in every language):** [List of Valid Charsets](https://www.chilkatsoft.com/ai-docs/v/11.7.0/articles/charsets_supported_by_chilkat.md)

Uncompresses a .Z file that contains a text file. The contents of the text file are returned as a string. The character encoding of the text file is specified by `charset`. Typical charsets are `iso-8859-1`, `utf-8`, `windows-1252`, `shift_JIS`, `big5`, etc.

Returns True for success, False for failure.

### UnixCompress.UnTarZ

`Chilkat 11.7.0 · pascal · UnixCompress · UnTarZ · method`

```pascal
function  UnTarZ(const zFilename: string;
    const destDir: string;
    bNoAbsolute: Boolean): Boolean;
```

Unpacks a .tar.Z file. The decompress and untar occur in streaming mode. There are no temporary files and the memory footprint is constant (and small) while untarring.

Returns True for success, False for failure.

## Events and callbacks

Chilkat for Pascal supports three synchronous event callbacks: `OnAbortCheck`, `OnPercentDone`, and `OnProgressInfo`. Each is a property of the class; assign a method of one of your own objects (an *of object* handler) to receive the callbacks, or assign `nil` to unhook. The handler types are declared in the `Chilkat.Base` unit:

```pascal
TChilkatAbortCheckEvent   = function(Sender: TChilkatBase): Boolean of object;
TChilkatPercentDoneEvent  = function(Sender: TChilkatBase; PctDone: Integer): Boolean of object;
TChilkatProgressInfoEvent = procedure(Sender: TChilkatBase; const Name, Value: string) of object;
```

All Chilkat methods are synchronous, so callbacks are invoked on the thread that called the method -- if the method was called from the main thread, it is safe to access UI elements from the handler. The `HeartbeatMs` property controls the frequency of `OnAbortCheck` callbacks (the default of 0 means no AbortCheck events fire). Returning `True` from an `OnAbortCheck` or `OnPercentDone` handler aborts the running method.

### UnixCompress.AbortCheck (event)

`Chilkat 11.7.0 · pascal · UnixCompress · AbortCheck · event`

```pascal
// TChilkatAbortCheckEvent = function(Sender: TChilkatBase): Boolean of object;

property OnAbortCheck: TChilkatAbortCheckEvent;
```

Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the `HeartbeatMs` property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.

**Event callback implementation:**

```pascal
// A handler is a method of one of your own classes, e.g. a form:
function TMyObject.UnixCompressAbortCheck(Sender: TChilkatBase): Boolean;
begin
  // Called every HeartbeatMs milliseconds while a method is running.
  // Return True to abort the method; return False to continue.
  Result := False;
end;
```

**To add an event handler:**

```pascal
unixcompress := TUnixCompress.Create;
unixcompress.HeartbeatMs := 250;   // fire OnAbortCheck 4 times per second
unixcompress.OnAbortCheck := MyObject.UnixCompressAbortCheck;
```

### UnixCompress.PercentDone (event)

`Chilkat 11.7.0 · pascal · UnixCompress · PercentDone · event`

```pascal
// TChilkatPercentDoneEvent = function(Sender: TChilkatBase; PctDone: Integer): Boolean of object;

property OnPercentDone: TChilkatPercentDoneEvent;
```

This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The `pctDone` argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have `pctDone` equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).

The PercentDone callback also acts as an `AbortCheck` event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.

To abort the operation, set the `abort` output argument to `True`. This will cause the method to terminate and return a failure status or corresponding failure value.

**Event callback implementation:**

```pascal
// A handler is a method of one of your own classes, e.g. a form:
function TMyObject.UnixCompressPercentDone(Sender: TChilkatBase; PctDone: Integer): Boolean;
begin
  // PctDone ranges from 1 to 100.
  WriteLn('Percent done: ', PctDone);
  // Return True to abort the method; return False to continue.
  Result := False;
end;
```

**To add an event handler:**

```pascal
unixcompress := TUnixCompress.Create;
unixcompress.OnPercentDone := MyObject.UnixCompressPercentDone;
```

### UnixCompress.ProgressInfo (event)

`Chilkat 11.7.0 · pascal · UnixCompress · ProgressInfo · event`

```pascal
// TChilkatProgressInfoEvent = procedure(Sender: TChilkatBase; const Name, Value: string) of object;

property OnProgressInfo: TChilkatProgressInfoEvent;
```

This event callback provides `tag name`/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.

Note: Some Chilkat methods don't fire any ProgressInfo events.

**Event callback implementation:**

```pascal
// A handler is a method of one of your own classes, e.g. a form:
procedure TMyObject.UnixCompressProgressInfo(Sender: TChilkatBase; const Name, Value: string);
begin
  WriteLn(Name, ': ', Value);
end;
```

**To add an event handler:**

```pascal
unixcompress := TUnixCompress.Create;
unixcompress.OnProgressInfo := MyObject.UnixCompressProgressInfo;
```