Manifest Tool

Say hello to mf@jbangdev — the new, delightfully simple way to peek inside any JAR’s manifest!

Ever wondered what secrets lurk in META-INF/MANIFEST.MF? Tired of squinting at cryptic key-value pairs or wrangling with unzip just to see what’s inside? Now you can summon manifest magic with a single command:

mf `jbang info jar com.h2database:h2:2.2.224`

This will use jbang to fetch the jar for h2 and then use mf to print the manifest.

Manifest-Version: 1.0
Implementation-Title: H2 Database Engine
Implementation-URL: https://h2database.com
Implementation-Version: 2.2.224
Build-Jdk: 1.8
Created-By: 1.8.0_281-b09 (Oracle Corporation)
Main-Class: org.h2.tools.Console
Automatic-Module-Name: com.h2database
Bundle-Activator: org.h2.util.DbDriverActivator
Bundle-ManifestVersion: 2
Bundle-Name: H2 Database Engine
Bundle-SymbolicName: com.h2database
Bundle-Vendor: H2 Group
Bundle-Version: 2.2.224
Bundle-License: https://h2database.com/html/license.html
Bundle-Category: jdbc
Multi-Release: true
Import-Package: javax.crypto,javax.crypto.spec,javax.management,javax.naming;resolution:=optional,javax.naming.directory;resolution:=optional,..
Export-Package: org.h2;version="2.2.224",org.h2.api;version="2.2.224",org.h2.constant;version="2.2.224",org.h2.fulltext;version="2.2.224"...
Provide-Capability: osgi.service;objectClass:List<String>=org.osgi.service.jdbc.DataSourceFactory
Premain-Class: org.h2.util.Profiler

Installation

You can run it directly using jbang mf@jbangdev or install it using jbang install mf@jbangdev to get it as a standalone tool.

Structured output

You’ll notice keys like Import-Package and Export-Package are very long and hard to read. mf allows enabling structured output (-s or --structured) that supports certain well-known keys and when enabled will print the values as lists or maps.

mf `jbang info jar com.h2database:h2:2.2.224` -s

Manifest-Version: 1.0
Implementation-Title: H2 Database Engine
...
Import-Package:
  javax.crypto: true
  javax.crypto.spec: true
  javax.management: true
  javax.naming:
    resolution: optional
  javax.naming.directory:
    resolution: optional
  javax.naming.spi:
    resolution: optional
  ...
Export-Package:
  org.h2:
    version: 2.2.224
  org.h2.api:
    version: 2.2.224
  org.h2.constant:
    version: 2.2.224
  org.h2.fulltext:
    version: 2.2.224
...
Provide-Capability: osgi.service;objectClass:List<String>=org.osgi.service.jdbc.DataSourceFactory
Premain-Class: org.h2.util.Profiler

Still long, but much easier to read.

Filtering

mf supports filtering the manifest keys using a regex.

In its simplest form it lets you substring on keys

mf `jbang info jar com.h2database:h2:2.2.224` -s version

Manifest-Version: 1.0
Implementation-Version: 2.2.224
...

but you can also use a regex to filter the keys.

mf `jbang info jar com.h2database:h2:2.2.224` "bundle|version"

Manifest-Version: 1.0
Implementation-Version: 2.2.224
Bundle-Activator: org.h2.util.DbDriverActivator
Bundle-ManifestVersion: 2
Bundle-Name: H2 Database Engine
Bundle-SymbolicName: com.h2database
Bundle-Vendor: H2 Group
Bundle-Version: 2.2.224
Bundle-License: https://h2database.com/html/license.html
Bundle-Category: jdbc

JSON & YAML

Finally, mf supports JSON(--json) and YAML(--yaml) output.

mf `jbang info jar com.h2database:h2:2.2.224` --json

and they can be combined with the other options:

mf `jbang info jar com.h2database:h2:2.2.224` --yaml -s "version|package"

Manifest-Version: "1.0"
Implementation-Version: "2.2.224"
Bundle-ManifestVersion: "2"
Bundle-Version: "2.2.224"
Import-Package:
  javax.crypto: true
  javax.crypto.spec: true
  javax.management: true
  javax.naming:
    resolution: "optional"
  javax.naming.directory:
    resolution: "optional"
  javax.naming.spi:
    resolution: "optional"
  javax.net: true
  javax.net.ssl: true
  javax.script:
    resolution: "optional"
  ...
Export-Package:
  org.h2:
    version: "2.2.224"
  org.h2.api:
    version: "2.2.224"
  org.h2.constant:
    version: "2.2.224"
  org.h2.fulltext:
    version: "2.2.224"
  org.h2.jdbc:
    version: "2.2.224"
  ...