Allow using shell aliases in interactive custom commands (#3793)

- **PR Description**

When executing an interactive custom command, use the user's shell
rather than "bash", and pass the -i flag. This makes it possible to use
shell aliases or shell functions which are not available in
non-interactive shells.

In previous attempts to solve this, concerns were brought up: [this
one](https://github.com/jesseduffield/lazygit/pull/2096#issuecomment-1257072541)
is addressed by using the interactive shell only for custom commands but
not anything else. [This
one](https://github.com/jesseduffield/lazygit/pull/2096#issuecomment-1343341795)
is a little dubious and unconfirmed, so I'm not very worried about it.

Supersedes #2096 and #3299. Fixes #770, #899, and #1642.

pkg/commands/git_cmd_obj_builder.go

@@ -38,6 +38,10 @@ func (self *gitCmdObjBuilder) NewShell(cmdStr string) oscommands.ICmdObj {
 	return self.innerBuilder.NewShell(cmdStr).AddEnvVars(defaultEnvVar)
 }
 
+func (self *gitCmdObjBuilder) NewInteractiveShell(cmdStr string) oscommands.ICmdObj {
+	return self.innerBuilder.NewInteractiveShell(cmdStr).AddEnvVars(defaultEnvVar)
+}
+
 func (self *gitCmdObjBuilder) Quote(str string) string {
 	return self.innerBuilder.Quote(str)
 }

pkg/commands/oscommands/cmd_obj_builder.go

@@ -14,6 +14,8 @@ type ICmdObjBuilder interface {
 	New(args []string) ICmdObj
 	// NewShell takes a string like `git commit` and returns an executable shell command for it e.g. `sh -c 'git commit'`
 	NewShell(commandStr string) ICmdObj
+	// Like NewShell, but uses the user's shell rather than "bash", and passes -i to it
+	NewInteractiveShell(commandStr string) ICmdObj
 	// Quote wraps a string in quotes with any necessary escaping applied. The reason for bundling this up with the other methods in this interface is that we basically always need to make use of this when creating new command objects.
 	Quote(str string) string
 }
@@ -43,10 +45,23 @@ func (self *CmdObjBuilder) NewWithEnviron(args []string, env []string) ICmdObj {
 }
 
 func (self *CmdObjBuilder) NewShell(commandStr string) ICmdObj {
-	var quotedCommand string
+	quotedCommand := self.quotedCommandString(commandStr)
+	cmdArgs := str.ToArgv(fmt.Sprintf("%s %s %s", self.platform.Shell, self.platform.ShellArg, quotedCommand))
+
+	return self.New(cmdArgs)
+}
+
+func (self *CmdObjBuilder) NewInteractiveShell(commandStr string) ICmdObj {
+	quotedCommand := self.quotedCommandString(commandStr)
+	cmdArgs := str.ToArgv(fmt.Sprintf("%s %s %s %s", self.platform.InteractiveShell, self.platform.InteractiveShellArg, self.platform.ShellArg, quotedCommand))
+
+	return self.New(cmdArgs)
+}
+
+func (self *CmdObjBuilder) quotedCommandString(commandStr string) string {
 	// Windows does not seem to like quotes around the command
 	if self.platform.OS == "windows" {
-		quotedCommand = strings.NewReplacer(
+		return strings.NewReplacer(
 			"^", "^^",
 			"&", "^&",
 			"|", "^|",
@@ -54,13 +69,9 @@ func (self *CmdObjBuilder) NewShell(commandStr string) ICmdObj {
 			">", "^>",
 			"%", "^%",
 		).Replace(commandStr)
-	} else {
-		quotedCommand = self.Quote(commandStr)
 	}
 
-	cmdArgs := str.ToArgv(fmt.Sprintf("%s %s %s", self.platform.Shell, self.platform.ShellArg, quotedCommand))
-
-	return self.New(cmdArgs)
+	return self.Quote(commandStr)
 }
 
 func (self *CmdObjBuilder) CloneWithNewRunner(decorate func(ICmdObjRunner) ICmdObjRunner) *CmdObjBuilder {

pkg/commands/oscommands/dummies.go

@@ -51,11 +51,13 @@ func NewDummyCmdObjBuilder(runner ICmdObjRunner) *CmdObjBuilder {
 }
 
 var dummyPlatform = &Platform{
-	OS:              "darwin",
-	Shell:           "bash",
-	ShellArg:        "-c",
-	OpenCommand:     "open {{filename}}",
-	OpenLinkCommand: "open {{link}}",
+	OS:                  "darwin",
+	Shell:               "bash",
+	InteractiveShell:    "bash",
+	ShellArg:            "-c",
+	InteractiveShellArg: "-i",
+	OpenCommand:         "open {{filename}}",
+	OpenLinkCommand:     "open {{link}}",
 }
 
 func NewDummyOSCommandWithRunner(runner *FakeCmdObjRunner) *OSCommand {

pkg/commands/oscommands/os.go

@@ -35,11 +35,13 @@ type OSCommand struct {
 
 // Platform stores the os state
 type Platform struct {
-	OS              string
-	Shell           string
-	ShellArg        string
-	OpenCommand     string
-	OpenLinkCommand string
+	OS                  string
+	Shell               string
+	InteractiveShell    string
+	ShellArg            string
+	InteractiveShellArg string
+	OpenCommand         string
+	OpenLinkCommand     string
 }
 
 // NewOSCommand os command runner

pkg/commands/oscommands/os_default_platform.go

@@ -4,15 +4,26 @@
 package oscommands
 
 import (
+	"os"
 	"runtime"
 )
 
 func GetPlatform() *Platform {
 	return &Platform{
-		OS:              runtime.GOOS,
-		Shell:           "bash",
-		ShellArg:        "-c",
-		OpenCommand:     "open {{filename}}",
-		OpenLinkCommand: "open {{link}}",
+		OS:                  runtime.GOOS,
+		Shell:               "bash",
+		InteractiveShell:    getUserShell(),
+		ShellArg:            "-c",
+		InteractiveShellArg: "-i",
+		OpenCommand:         "open {{filename}}",
+		OpenLinkCommand:     "open {{link}}",
 	}
 }
+
+func getUserShell() string {
+	if shell := os.Getenv("SHELL"); shell != "" {
+		return shell
+	}
+
+	return "bash"
+}

pkg/commands/oscommands/os_windows.go

@@ -2,8 +2,10 @@ package oscommands
 
 func GetPlatform() *Platform {
 	return &Platform{
-		OS:       "windows",
-		Shell:    "cmd",
-		ShellArg: "/c",
+		OS:                  "windows",
+		Shell:               "cmd",
+		InteractiveShell:    "cmd",
+		ShellArg:            "/c",
+		InteractiveShellArg: "",
 	}
 }

pkg/gui/controllers/custom_command_action.go

@@ -31,7 +31,7 @@ func (self *CustomCommandAction) Call() error {
 
 			self.c.LogAction(self.c.Tr.Actions.CustomCommand)
 			return self.c.RunSubprocessAndRefresh(
-				self.c.OS().Cmd.NewShell(command),
+				self.c.OS().Cmd.NewInteractiveShell(command),
 			)
 		},
 		HandleDeleteSuggestion: func(index int) error {