Variables in manifest

Use of variables in the manifest.mf file

The values of certain fields in the manifest file can be set using predefined variables. These variables are replaced with their actual values at runtime.

The two most common use cases of variables in a Command Launcher’s manifest.mf file are:

  1. Referencing files that are located in the package directory itself
  2. Providing system/architecture-aware commands, for example, .sh script for linux, and .bat script for windows

Available Variables

Variable NameVariable Description
PackageDirThe absolute path of the package
RootSame as the “PackageDir” variable
CacheSame as the “PackageDir” variable
OsThe OS: “windows”, “linux”, or “darwin”
ArchThe system architecture: “arm64”, “amd64”
BinaryThe binary file name of the Command Launcher
ExtensionThe system-aware binary extension, "" for linux, “.exe” for windows
ScriptExtensionThe system-aware script extension, “.sh” for linux, “.bat” for windows

Fields that accept variables

Variables can only be used in the command properties: executable, args, and validArgsCmd

How to use these variables

You can reference them in this format: {{.Variable}}. For example:

"cmds": [
  {
    "name": "variable-demo",
    "type": "executable",
    "executable": "{{.PackageDir}}/bin/script{{.ScripteExtension}}",
  }
]

The executable on Linux will be a script called script.sh located in the bin folder of the package. On windows, the executable will be a script called script.bat.

If Else

One common scenario is to have a different path or file name, depending on what OS Command Launcher is running on. You can use a conditional structure (if-else) in the fields that accept variables. For example:

"cmds": [
  {
    "name": "variable-demo",
    "type": "executable",
    "executable": "{{.PackageDir}}/bin/script{{if eq .Os \"windows\"}}.ps1{{else}}.sh{{end}}",
  }
]

The executable on Linux will be a script called script.sh located in the bin folder of the package. On Windows, the executable will be a script called script.ps1.

Advanced usage of variables

See golang text/template for advanced usage.

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