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added modification example

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Mathias Buus 2013-12-20 20:50:02 +01:00
parent d92830313b
commit 315814b52e
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README.md
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@ -1,6 +1,6 @@
# tar-stream # tar-stream
tar-stream is a streaming tar parser and generator and nothing else. It is streams2 and operates purely using streams which means you can extract/parse tarballs without ever hitting the file system. tar-stream is a streaming tar parser and generator and nothing else. It is streams2 and operates purely using streams which means easily you can extract/parse tarballs without ever hitting the file system.
npm install tar-stream npm install tar-stream
@ -14,21 +14,21 @@ To create a pack stream use `tar.pack()` and call `pack.entry(header, [callback]
``` js ``` js
var tar = require('tar-stream'); var tar = require('tar-stream');
var p = tar.pack(); // p is a streams2 stream var pack = tar.pack(); // p is a streams2 stream
// add a file called my-test.txt with the content "Hello World!" // add a file called my-test.txt with the content "Hello World!"
p.entry({ name: 'my-test.txt' }, 'Hello World!'); pack.entry({ name: 'my-test.txt' }, 'Hello World!');
// add a file called my-stream-test.txt from a stream // add a file called my-stream-test.txt from a stream
myStream.pipe(p.entry({ name: 'my-stream-test.txt' }, function(err) { myStream.pipe(pack.entry({ name: 'my-stream-test.txt' }, function(err) {
// the stream was added // the stream was added
})); }));
// no more entries // no more entries
p.finalize(); pack.finalize();
// pipe the pack stream somewhere // pipe the pack stream somewhere
p.pipe(process.stdout); pack.pipe(process.stdout);
``` ```
## Extracting ## Extracting
@ -36,9 +36,9 @@ p.pipe(process.stdout);
To extract a stream use `tar.extract()` and listen for `extract.on('entry', header, stream, callback)` To extract a stream use `tar.extract()` and listen for `extract.on('entry', header, stream, callback)`
``` js ``` js
var e = tar.extract(); var extract = tar.extract();
e.on('entry', function(header, stream, callback) { extract.on('entry', function(header, stream, callback) {
// header is the tar header // header is the tar header
// stream is the content body (might be an empty stream) // stream is the content body (might be an empty stream)
// call callback when you are done with this entry // call callback when you are done with this entry
@ -49,11 +49,39 @@ e.on('entry', function(header, stream, callback) {
}); });
}); });
e.on('finish', function() { extract.on('finish', function() {
// all entries read // all entries read
}); });
packStream.pipe(e); pack.pipe(extract);
```
## Modifying existing tarballs
Using tar-stream it is easy to rewrite paths / change modes etc in an existing tarball.
``` js
var extract = tar.extract();
var pack = tar.pack();
var path = require('path');
extract.on('entry', function(header, stream, callback) {
// let's prefix all names with 'tmp'
header.name = path.join('tmp', header.name);
// write the new entry to the pack stream
stream.pipe(pack.entry(header, callback));
});
extract.on('finish', function() {
// all entries done - lets finalize it
pack.finalize();
});
// pipe the old tarball to the extractor
oldTarball.pipe(extract);
// pipe the new tarball the another stream
pack.pipe(newTarball);
``` ```
## Headers ## Headers