Quoting character(s), put around the command passed to the shell, for the "!" and ":!" commands. Includes the redirection. See 'shellquote' to exclude the redirection. It's probably not useful to set both options. When the value is '(' then ')' is appended. When the value is '"(' then ')"' is appended. When the value is '(' then also see 'shellxescape'. This is an empty string by default on most systems, but is known to be useful for on Win32 version, either for cmd.exe, powershell.exe, or pwsh.exe which automatically strips off the first and last quote on a command, or 3rd-party shells such as the MKS Korn Shell or bash, where it should be """. The default is adjusted according the value of 'shell', to reduce the need to set this option by the user. See dos-shell. This option cannot be set from a modeline or in the sandbox, for security reasons.

(default: ""; for Win32, when 'shell' is cmd.exe: "(" for Win32, when 'shell' is powershell.exe: """ for Win32, when 'shell' contains "sh" somewhere: """ for Unix, when using system(): """)