Before: Save &shell Save &shellcmdflag After: Restore Execute(sh should be used when the shell is fish): if !has('win32') " Set something else, so we will replace that too. let &shellcmdflag = '-f' let &shell = 'fish' AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar') let &shell = '/usr/bin/fish' AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar') let &shell = '/usr/local/bin/fish' AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar') endif Execute(sh should be used when the shell is powershell): if !has('win32') " Set something else, so we will replace that too. let &shellcmdflag = '-f' let &shell = 'pwsh' AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar') let &shell = '/usr/bin/pwsh' AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar') let &shell = '/usr/local/bin/pwsh' AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar') endif Execute(Other shells should be used when set): if !has('win32') let &shell = '/bin/bash' let &shellcmdflag = '-c' AssertEqual ['/bin/bash', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar') endif Execute(cmd /s/c as a string should be used on Windows): if has('win32') let &shell = 'who cares' let &shellcmdflag = 'whatever' AssertEqual 'cmd /s/c "foobar"', ale#job#PrepareCommand(bufnr(''), 'foobar') endif