Spawns {cmd} as a job. If {cmd} is a List it runs directly (no 'shell'). If {cmd} is a String it runs in the 'shell', like this: :call jobstart(split(&shell) + split(&shellcmdflag) + ['{cmd}']) (See |shell-unquoting| for details.) Example: :call jobstart('nvim -h', {'on_stdout':{j,d,e->append(line('.'),d)}}) Returns |job-id| on success, 0 on invalid arguments (or job table is full), -1 if {cmd}[0] or 'shell' is not executable. The returned job-id is a valid |channel-id| representing the job's stdio streams. Use |chansend()| (or |rpcnotify()| and |rpcrequest()| if "rpc" was enabled) to send data to stdin and |chanclose()| to close the streams without stopping the job. See |job-control| and |RPC|. NOTE: on Windows if {cmd} is a List:

• cmd[0] must be an executable (not a "built-in"). If it is in $PATH it can be called by name, without an extension: :call jobstart(['ping', 'neovim.io']) If it is a full or partial path, extension is required: :call jobstart(['System32\ping.exe', 'neovim.io'])
• {cmd} is collapsed to a string of quoted args as expected by CommandLineToArgvW https://msdn.microsoft.com/bb776391 unless cmd[0] is some form of "cmd.exe". {opts} is a dictionary with these keys: clear_env: (boolean) env defines the job environment exactly, instead of merging current environment. cwd: (string, default=|current-directory|) Working directory of the job. detach: (boolean) Detach the job process: it will not be killed when Nvim exits. If the process exits before Nvim, on_exit will be invoked. env: (dict) Map of environment variable name:value pairs extending (or replacing if |clear_env|) the current environment. height: (number) Height of the pty terminal. |on_exit|: (function) Callback invoked when the job exits. |on_stdout|: (function) Callback invoked when the job emits stdout data. |on_stderr|: (function) Callback invoked when the job emits stderr data. overlapped: (boolean) Set FILE_FLAG_OVERLAPPED for the standard input/output passed to the child process. Normally you do not need to set this. (Only available on MS-Windows, On other platforms, this option is silently ignored.) pty: (boolean) Connect the job to a new pseudo terminal, and its streams to the master file descriptor. Then on_stderr is ignored, on_stdout receives all output. rpc: (boolean) Use |msgpack-rpc| to communicate with the job over stdio. Then on_stdout is ignored, but on_stderr can still be used. stderr_buffered: (boolean) Collect data until EOF (stream closed) before invoking on_stderr. |channel-buffered| stdout_buffered: (boolean) Collect data until EOF (stream closed) before invoking on_stdout. |channel-buffered| width: (number) Width of the pty terminal. {opts} is passed as |self| dictionary to the callback; the caller may set other keys to pass application-specific data. Returns:
• |channel-id| on success
• 0 on invalid arguments
• -1 if {cmd}[0] is not executable. See also |job-control|, |channel|, |msgpack-rpc|.