Add support for the BROWSER environment variablesupport-for-BROWSER-environment-variable

Allow user-defined URL-opening commands via the BROWSER environment
variable. This enables using a non-default browser, or changing the
browser for a single command.

For example, on Mac:

    $ export BROWSER='open -a Firefox'

Windows:

    > setx BROWSER "start iexplore"

In UNIX environments, the command is run through `$SHELL -c`, or
`/bin/sh` if `$SHELL` is not set. On Windows, it uses `cmd /c`.

Ensure that URLs are properly quoted between UNIX and Windows
environments in `fmtBrowserCmd()`.

1 files changed, 16 insertions, 1 deletions

diff --git a/browser.go b/browser.go
index 3e59690..7c60821 100644
--- a/browser.go
+++ b/browser.go
@@ -55,9 +55,24 @@ func OpenURL(url string) error {
 }
 
 func runCmd(prog string, args ...string) error {
-	cmd := exec.Command(prog, args...)
+	var cmd *exec.Cmd
+
+	browser := envBrowserCmd()
+	if browser != "" {
+		sh, flag := shell()
+		url := args[len(args)-1]
+		browserCmd := fmtBrowserCmd(browser, url)
+		cmd = exec.Command(sh, flag, browserCmd)
+	} else {
+		cmd = exec.Command(prog, args...)
+	}
+
 	cmd.Stdout = Stdout
 	cmd.Stderr = Stderr
 	setFlags(cmd)
 	return cmd.Run()
 }
+
+func envBrowserCmd() string {
+	return os.Getenv("BROWSER")
+}