Add shelldash Option to Disable -- Appending in Shell Commands

[clappedscant906]

Pull Request: Add shelldash Option to Disable -- Appending in Shell Commands

Summary

This PR adds a new shelldash option to control whether lf appends -- to shell command arguments. This fixes compatibility issues with shells like nushell that do not support the -- argument separator in the same way as traditional POSIX shells.

Problem Description

lf currently unconditionally appends -- to shell command arguments on Unix/Linux systems to prevent arguments from being interpreted as shell options. While this works correctly for POSIX-compliant shells (sh, bash, zsh), it causes errors with nushell.

Example Error with Nushell

lfrc configuration:

set shell nu
set shellflag "-c"
cmd open $echo test

Error when invoking the command:

Error: nu::parser::unknown_flag
× The `nu` command doesn't have flag named empty.
╭─[source:2:3]
" -- nu -c "echo test
·                   ─┬
·                    ╰── unknown flag
╰────
help: Use `--help` to see available flags

The issue is that nushell interprets the -- as a flag (or incorrectly parses it), whereas traditional shells use -- as a standard end-of-options marker.

Solution

Added a new boolean option shelldash that defaults to true (preserving current behavior for existing users). Users working with nushell or other incompatible shells can now disable the -- appending.

After Fix - Working Configuration

set shell nu
set shelldash false
set shellflag "-c"

cmd open $print test; input

This configuration now works correctly - it prints "test" and waits for user input.

Changes Made

File	Change
opts.go	Added shelldash bool field to gOpts struct
opts.go	Set default value gOpts.shelldash = true in init()
eval.go	Added option parsing for shelldash, noshelldash, shelldash!
os.go	Modified shellCommand() to conditionally append -- based on gOpts.shelldash

Key Implementation Detail

Before (os.go):

args = append([]string{gOpts.shellflag, s, "--"}, args...)

After (os.go):

if gOpts.shelldash {
    args = append([]string{gOpts.shellflag, s, "--"}, args...)
} else {
    args = append([]string{gOpts.shellflag, s}, args...)
}

Usage

Users can control the behavior in their lfrc:

# Default behavior (append --)
set shelldash

# Disable the -- appending (for nushell, etc.)
set noshelldash
# or
set shelldash false

# Toggle with !
set shelldash!

Backward Compatibility

• The option defaults to true, so existing configurations continue to work unchanged
• No breaking changes to the API or existing behavior

Testing Environment

• lf version: r40
• nushell version: 0.109.1

Checklist

• Default behavior unchanged (-- is still appended by default)
• set shelldash enables -- appending
• set noshelldash disables -- appending
• set shelldash! toggles the behavior
• Tested with nushell (the primary use case)
• Verified compatibility with POSIX shells (sh, bash)

[CatsDeservePets]

So this is basically aims to fix

• Multishell/Crossplatform handling of -- #1784

There has been an attempt to solve this problem, however the PR was never finished

• feat: temlated shell command #1852

I honestly do prefer the approach suggested by @joelim-work in the original issue as it seems more flexible and potentially also useful for other shells.

[CatsDeservePets]

Hello, @clappedscant906!
Are you still interested in this?

[joelim-work]

A 'shell' is essentially a runner that can execute a command string, possibly with some arguments. For example, with the configuration cmd greet %printf "Hello, %s!" "$1" and the invocation :greet world:

• The command string is printf "Hello, %s!" "$1"
• The argument is world
• The runner is sh -c <command> -- <args>, which becomes sh -c 'printf "Hello, %s!" "$1"' -- world

Unfortunately the existing design splits the shell configuration into shell, shellflag and shellopts which isn't very flexible. Introducing an option like shelldash may fix the problem for shells that don't require --, but ultimately doesn't address the flaws in the original design. shellopts is already a string array value (split by :), perhaps the same idea could be used to configure the shell, using placeholders for the command string and arguments.

[CatsDeservePets]

Also related

• [Feature request] open programs directly #1627