Exec args always expanded

[hborham]

Within the sh package, args are being expanded in the case where normal sh command would not expand args within single quotes. Example command:

pact-broker create-webhook --user='admin:${user.bitbucketAppPassword}'

1. Via normal shell the single quotes will not expand ${user.bitbucketAppPassword}
2. Via mage the expansion occurs and the actual command becomes:
   pact-broker create-webhook --user='admin:'

mage/sh/cmd.go

Lines 92 to 115 in 26cdb5c

	// Exec executes the command, piping its stderr to mage's stderr and
	// piping its stdout to the given writer. If the command fails, it will return
	// an error that, if returned from a target or mg.Deps call, will cause mage to
	// exit with the same code as the command failed with. Env is a list of
	// environment variables to set when running the command, these override the
	// current environment variables set (which are also passed to the command). cmd
	// and args may include references to environment variables in $FOO format, in
	// which case these will be expanded before the command is run.
	//
	// Ran reports if the command ran (rather than was not found or not executable).
	// Code reports the exit code the command returned if it ran. If err == nil, ran
	// is always true and code is always 0.
	func Exec(env map[string]string, stdout, stderr io.Writer, cmd string, args ...string) (ran bool, err error) {
	expand := func(s string) string {
	s2, ok := env[s]
	if ok {
	return s2
	}
	return os.Getenv(s)
	}
	cmd = os.Expand(cmd, expand)
	for i := range args {
	args[i] = os.Expand(args[i], expand)
	}

[fergonco]

Similar problem here. I am calling sh.Exec with a list of arguments one of which contains $. I want the literal $ but mage tries to expand it and I found no way to prevent this.

[rkennedy]

I've just submitted a PR that I think would solve this. But @hborham, note that for your example to work the way you want, you'd need to remove the apostrophes from your arguments. Apostrophes are one way to avoid having the shell expand environment variables. In doing so, the shell would strip the apostrophes from the argument prior to invoking the given command, so pact-broker would receive literally --user=admin:${user.bitbucketAppPassword} as its argument. Using my PR, you might write code like this:

sh.Run("pact-broker", "create-webhook", sh.Escape("--user=admin:${user.bitbucketAppPassword}"))