Modeline Security, Option Summary, and Hidden Options in Vim

'modeline' is off or 'modelines' is 0 no lines are checked. Note that for the first form all of the rest of the line is used, thus a line like: > /* vi:ts=4: */ will give an error message for the trailing "*/". This line is OK: > /* vi:set ts=4: */ If an error is detected the rest of the line is skipped. If you want to include a ':' in a set command precede it with a '\'. The backslash in front of the ':' will be removed. Example: > /* vi:set fillchars=stl\:^,vert\:\|: */ This sets the 'fillchars' option to "stl:^,vert:\|". Only a single backslash before the ':' is removed. Thus to include "\:" you have to specify "\\:". *E992* No other commands than "set" are supported, for security reasons (somebody might create a Trojan horse text file with modelines). And not all options can be set. For some options a flag is set, so that when the value is used the |sandbox| is effective. Some options can only be set from the modeline when 'modelineexpr' is set (the default is off). Still, there is always a small risk that a modeline causes trouble. E.g., when some joker sets 'textwidth' to 5 all your lines are wrapped unexpectedly. So disable modelines before editing untrusted text. The mail ftplugin does this, for example. Hint: If you would like to do something else than setting an option, you could define an autocommand that checks the file for a specific string. For example: > au BufReadPost * if getline(1) =~ "VAR" | call SetVar() | endif And define a function SetVar() that does something with the line containing "VAR". ============================================================================== 3. Options summary *option-summary* In the list below all the options are mentioned with their full name and with an abbreviation if there is one. Both forms may be used. In this document when a boolean option is "set" that means that ":set option" is entered. When an option is "reset", ":set nooption" is used. Most options are the same in all windows and buffers. There are a few that are specific to how the text is presented in a window. These can be set to a different value in each window. For example the 'list' option can be set in one window and reset in another for the same text, giving both types of view at the same time. There are a few options that are specific to a certain file. These can have a different value for each file or buffer. For example the 'textwidth' option can be 78 for a normal text file and 0 for a C program. global one option for all buffers and windows local to window each window has its own copy of this option local to buffer each buffer has its own copy of this option When creating a new window the option values from the currently active window are used as a default value for the window-specific options. For the buffer-specific options this depends on the 's' and 'S' flags in the 'cpoptions' option. If 's' is included (which is the default) the values for buffer options are copied from the currently active buffer when a buffer is first entered. If 'S' is present the options are copied each time the buffer is entered, this is almost like having global options. If 's' and 'S' are not present, the options are copied from the currently active buffer when the buffer is created. Hidden options *hidden-options* Not all options are supported in all versions. This depends on the supported features and sometimes on the system. A remark about this is in curly braces below. When an option is not supported, it is called a hidden option. Trying to get the value of a hidden option will not give an error, it will return the default value for that option instead. You can't change the value of a hidden option. To test if "foo" is a valid option name, use something like this: > if exists('&foo') This also returns true for a hidden option. To test if option "foo" is really supported use something like this: > if exists('+foo') < *E355* A jump table

This section addresses modeline security risks and suggests disabling them for untrusted text. It then provides an overview of Vim options, distinguishing between global, window-local, and buffer-local options, and how they are inherited when creating new windows or buffers. Finally, it discusses hidden options, which are unsupported in certain versions or systems, and how to check for the existence and support of an option using 'exists("&foo")' and 'exists("+foo")'.