sub

sub is a command-line tool with a clean interface that runs a command in multiple sub-directories in parallel. It was originally created to speed up developing involving multiple git repositories.

$ sub -h
Usage: sub [options] [--] <command>...

Options:
  -c string
    	Configuration file
  -j int
    	Number of concurrent subprocesses (default -1)
  -v	Print out the version and exit

Usage

sub obtains the list of sub-directories to run in from the configuration file, but if one isn't provided, then it just runs in all non-hidden sub-directories, a sensible default.

The format of a configuration file is a JSON formatted list of strings, each representing a sub-directory. It can be any non-existing path or the path to any directory:

[
  "foo",
  "bar",
  "baz",
  "../im/complicated"
]

If a path doesn't exist and is specified in the configuration file, it is automatically created as a directory.

The positional arguments to sub is the command itself. If a command requires flags, then you must prefix the command with --:

$ sub -- git branch -vv

By default, sub runs all the commands at once. If you have to throttle the number of simultaneous commands, pass a value for -j:

$ sub -j 4 git fetch

Future Features

• Accept line-based configuration, with a directory on each line, as input from stdin for shell interoperability.