# Vim documentation: usr_21

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    *usr_21.txt*	For Vim version 7.4.  Last change: 2012 Nov 02

    		     VIM USER MANUAL - by Bram Moolenaar

    			   Go away and come back

    This chapter goes into mixing the use of other programs with Vim.  Either by
    executing program from inside Vim or by leaving Vim and coming back later.
    Furthermore, this is about the ways to remember the state of Vim and restore
    it later.

    |21.1|	Suspend and resume
    |21.2|	Executing shell commands
    |21.3|	Remembering information; viminfo
    |21.4|	Sessions
    |21.5|	Views
    |21.6|	Modelines

         Next chapter: |usr_22.txt|  Finding the file to edit
     Previous chapter: |usr_20.txt|  Typing command-line commands quickly
    Table of contents: |usr_toc.txt|

    ==============================================================================

    *21.1*	Suspend and resume

    Like most Unix programs Vim can be suspended by pressing CTRL-Z.  This stops
    Vim and takes you back to the shell it was started in.  You can then do any
    other commands until you are bored with them.  Then bring back Vim with the
    "fg" command.

    	CTRL-Z
    	{any sequence of shell commands}
    	fg

    You are right back where you left Vim, nothing has changed.
       In case pressing CTRL-Z doesn't work, you can also use ":suspend".
    Don't forget to bring Vim back to the foreground, you would lose any changes
    that you made!

    Only Unix has support for this.  On other systems Vim will start a shell for
    you.  This also has the functionality of being able to execute shell commands.
    But it's a new shell, not the one that you started Vim from.
       When you are running the GUI you can't go back to the shell where Vim was
    started.  CTRL-Z will minimize the Vim window instead.

    ==============================================================================

    *21.2*	Executing shell commands

    To execute a single shell command from Vim use ":!{command}".  For example, to
    see a directory listing:

    	:!ls
    	:!dir

    The first one is for Unix, the second one for MS-Windows.
       Vim will execute the program.  When it ends you will get a prompt to hit
    <Enter>.  This allows you to have a look at the output from the command before
    returning to the text you were editing.
       The "!" is also used in other places where a program is run.  Let's take
    a look at an overview:

    	:!{program}		execute {program}
    	:r !{program}		execute {program} and read its output
    	:w !{program}		execute {program} and send text to its input
    	:[range]!{program}	filter text through {program}

    Notice that the presence of a range before "!{program}" makes a big
    difference.  Without it executes the program normally, with the range a number
    of text lines is filtered through the program.

    Executing a whole row of programs this way is possible.  But a shell is much
    better at it.  You can start a new shell this way:

    	:shell

    This is similar to using CTRL-Z to suspend Vim.  The difference is that a new
    shell is started.

    When using the GUI the shell will be using the Vim window for its input and
    output.  Since Vim is not a terminal emulator, this will not work perfectly.
    If you have trouble, try toggling the 'guipty' option.  If this still doesn't
    work well enough, start a new terminal to run the shell in.  For example with:

    	:!xterm&

    ==============================================================================

    *21.3*	Remembering information; viminfo

    After editing for a while you will have text in registers, marks in various
    files, a command line history filled with carefully crafted commands.  When
    you exit Vim all of this is lost.  But you can get it back!

    The viminfo file is designed to store status information:

    	Command-line and Search pattern history
    	Text in registers
    	Marks for various files
    	The buffer list
    	Global variables

    Each time you exit Vim it will store this information in a file, the viminfo
    file.  When Vim starts again, the viminfo file is read and the information
    restored.

    The 'viminfo' option is set by default to restore a limited number of items.
    You might want to set it to remember more information.  This is done through
    the following command:

    	:set viminfo=string

    The string specifies what to save.  The syntax of this string is an option
    character followed by an argument.  The option/argument pairs are separated by
    commas.
       Take a look at how you can build up your own viminfo string.  First, the ''
    option is used to specify how many files for which you save marks (a-z).  Pick
    a nice even number for this option (1000, for instance).  Your command now
    looks like this:

    	:set viminfo='1000

    The f option controls whether global marks (A-Z and 0-9) are stored.  If this
    option is 0, none are stored.  If it is 1 or you do not specify an f option,
    the marks are stored.  You want this feature, so now you have this:

    	:set viminfo='1000,f1

    The < option controls how many lines are saved for each of the registers.  By
    default, all the lines are saved.  If 0, nothing is saved.  To avoid adding
    thousands of lines to your viminfo file (which might never get used and makes
    starting Vim slower) you use a maximum of 500 lines:

    	:set viminfo='1000,f1,<500

    Other options you might want to use:
    	:	number of lines to save from the command line history
    	@	number of lines to save from the input line history
    	/	number of lines to save from the search history
    	r	removable media, for which no marks will be stored (can be
    		used several times)
    	!	global variables that start with an uppercase letter and
    		don't contain lowercase letters
    	h	disable 'hlsearch' highlighting when starting
    	%	the buffer list (only restored when starting Vim without file
    		arguments)
    	c	convert the text using 'encoding'
    	n	name used for the viminfo file (must be the last option)

    See the 'viminfo' option and |viminfo-file| for more information.

    When you run Vim multiple times, the last one exiting will store its
    information.  This may cause information that previously exiting Vims stored
    to be lost.  Each item can be remembered only once.

    GETTING BACK TO WHERE YOU STOPPED VIM

    You are halfway editing a file and it's time to leave for holidays.  You exit
    Vim and go enjoy yourselves, forgetting all about your work.  After a couple
    of weeks you start Vim, and type:

    	'0

    And you are right back where you left Vim.  So you can get on with your work.
       Vim creates a mark each time you exit Vim.  The last one is '0.  The
    position that '0 pointed to is made '1.  And '1 is made to '2, and so forth.
    Mark '9 is lost.
       The |:marks| command is useful to find out where '0 to '9 will take you.

    GETTING BACK TO SOME FILE

    If you want to go back to a file that you edited recently, but not when
    exiting Vim, there is a slightly more complicated way.  You can see a list of
    files by typing the command:

    	:oldfiles
     	1: ~/.viminfo
    	2: ~/text/resume.txt
    	3: /tmp/draft

    Now you would like to edit the second file, which is in the list preceded by
    "2:".  You type:

    	:e #<2

    Instead of ":e" you can use any command that has a file name argument, the
    "#<2" item works in the same place as "%" (current file name) and "#"
    (alternate file name).  So you can also split the window to edit the third
    file:

    	:split #<3

    That #<123 thing is a bit complicated when you just want to edit a file.
    Fortunately there is a simpler way:

    	:browse oldfiles
     	1: ~/.viminfo
    	2: ~/text/resume.txt
    	3: /tmp/draft
    	-- More --

    You get the same list of files as with |:oldfiles|.  If you want to edit
    "resume.txt" first press "q" to stop the listing.  You will get a prompt:

    	Type number and <Enter> (empty cancels):

    Type "2" and press <Enter> to edit the second file.

    More info at |:oldfiles|, |v:oldfiles| and |c_#<|.

    MOVE INFO FROM ONE VIM TO ANOTHER

    You can use the ":wviminfo" and ":rviminfo" commands to save and restore the
    information while still running Vim.  This is useful for exchanging register
    contents between two instances of Vim, for example.  In the first Vim do:

    	:wviminfo! ~/tmp/viminfo

    And in the second Vim do:

    	:rviminfo! ~/tmp/viminfo

    Obviously, the "w" stands for "write" and the "r" for "read".
       The ! character is used by ":wviminfo" to forcefully overwrite an existing
    file.  When it is omitted, and the file exists, the information is merged into
    the file.
       The ! character used for ":rviminfo" means that all the information is
    used, this may overwrite existing information.  Without the ! only information
    that wasn't set is used.
       These commands can also be used to store info and use it again later.  You
    could make a directory full of viminfo files, each containing info for a
    different purpose.

    ==============================================================================

    *21.4*	Sessions

    Suppose you are editing along, and it is the end of the day.  You want to quit
    work and pick up where you left off the next day.  You can do this by saving
    your editing session and restoring it the next day.
       A Vim session contains all the information about what you are editing.
    This includes things such as the file list, window layout, global variables,
    options and other information.  (Exactly what is remembered is controlled by
    the 'sessionoptions' option, described below.)
       The following command creates a session file:

    	:mksession vimbook.vim

    Later if you want to restore this session, you can use this command:

    	:source vimbook.vim

    If you want to start Vim and restore a specific session, you can use the
    following command:

    	vim -S vimbook.vim

    This tells Vim to read a specific file on startup.  The 'S' stands for
    session (actually, you can source any Vim script with -S, thus it might as
    well stand for "source").

    The windows that were open are restored, with the same position and size as
    before.  Mappings and option values are like before.
       What exactly is restored depends on the 'sessionoptions' option.  The
    default value is "blank,buffers,curdir,folds,help,options,winsize".

    	blank		keep empty windows
    	buffers		all buffers, not only the ones in a window
    	curdir		the current directory
    	folds		folds, also manually created ones
    	help		the help window
    	options		all options and mappings
    	winsize		window sizes

    Change this to your liking.  To also restore the size of the Vim window, for
    example, use:

    	:set sessionoptions+=resize

    SESSION HERE, SESSION THERE

    The obvious way to use sessions is when working on different projects.
    Suppose you store your session files in the directory "~/.vim".  You are
    currently working on the "secret" project and have to switch to the "boring"
    project:

    	:wall
    	:mksession! ~/.vim/secret.vim
    	:source ~/.vim/boring.vim

    This first uses ":wall" to write all modified files.  Then the current session
    is saved, using ":mksession!".  This overwrites the previous session.  The
    next time you load the secret session you can continue where you were at this
    point.  And finally you load the new "boring" session.

    If you open help windows, split and close various windows, and generally mess
    up the window layout, you can go back to the last saved session:

    	:source ~/.vim/boring.vim

    Thus you have complete control over whether you want to continue next time
    where you are now, by saving the current setup in a session, or keep the
    session file as a starting point.
       Another way of using sessions is to create a window layout that you like to
    use, and save this in a session.  Then you can go back to this layout whenever
    you want.
       For example, this is a nice layout to use:

    	+----------------------------------------+
    	|		   VIM - main help file  |
    	|					 |
    	|Move around:  Use the cursor keys, or "h|
    	|help.txt================================|
    	|explorer   |				 |
    	|dir	    |~				 ||||
    	|dir	    |~				 ||||
    	|file	    |~				 ||||
    	|file	    |~				 ||||
    	|file	    |~				 ||||
    	|file	    |~				 ||||
    	|~/=========|[No File]===================|
    	|					 |
    	+----------------------------------------+

    This has a help window at the top, so that you can read this text.  The narrow
    vertical window on the left contains a file explorer.  This is a Vim plugin
    that lists the contents of a directory.  You can select files to edit there.
    More about this in the next chapter.
       Create this from a just started Vim with:

    	:help
    	CTRL-W w
    	:vertical split ~/

    You can resize the windows a bit to your liking.  Then save the session with:

    	:mksession ~/.vim/mine.vim

    Now you can start Vim with this layout:

    	vim -S ~/.vim/mine.vim

    Hint: To open a file you see listed in the explorer window in the empty
    window, move the cursor to the filename and press "O".  Double clicking with
    the mouse will also do this.

    UNIX AND MS-WINDOWS

    Some people have to do work on MS-Windows systems one day and on Unix another
    day.  If you are one of them, consider adding "slash" and "unix" to
    'sessionoptions'.  The session files will then be written in a format that can
    be used on both systems.  This is the command to put in your vimrc file:

    	:set sessionoptions+=unix,slash

    Vim will use the Unix format then, because the MS-Windows Vim can read and
    write Unix files, but Unix Vim can't read MS-Windows format session files.
    Similarly, MS-Windows Vim understands file names with / to separate names, but
    Unix Vim doesn't understand \.

    SESSIONS AND VIMINFO

    Sessions store many things, but not the position of marks, contents of
    registers and the command line history.  You need to use the viminfo feature
    for these things.
       In most situations you will want to use sessions separately from viminfo.
    This can be used to switch to another session, but keep the command line
    history.  And yank text into registers in one session, and paste it back in
    another session.
       You might prefer to keep the info with the session.  You will have to do
    this yourself then.  Example:

    	:mksession! ~/.vim/secret.vim
    	:wviminfo! ~/.vim/secret.viminfo

    And to restore this again:

    	:source ~/.vim/secret.vim
    	:rviminfo! ~/.vim/secret.viminfo

    ==============================================================================

    *21.5*	Views

    A session stores the looks of the whole of Vim.  When you want to store the
    properties for one window only, use a view.
       The use of a view is for when you want to edit a file in a specific way.
    For example, you have line numbers enabled with the 'number' option and
    defined a few folds.  Just like with sessions, you can remember this view on
    the file and restore it later.  Actually, when you store a session, it stores
    the view of each window.
       There are two basic ways to use views.  The first is to let Vim pick a name
    for the view file.  You can restore the view when you later edit the same
    file.  To store the view for the current window:

    	:mkview

    Vim will decide where to store the view.  When you later edit the same file
    you get the view back with this command:

    	:loadview

    That's easy, isn't it?
       Now you want to view the file without the 'number' option on, or with all
    folds open, you can set the options to make the window look that way.  Then
    store this view with:

    	:mkview 1

    Obviously, you can get this back with:

    	:loadview 1

    Now you can switch between the two views on the file by using ":loadview" with
    and without the "1" argument.
       You can store up to ten views for the same file this way, one unnumbered
    and nine numbered 1 to 9.

    A VIEW WITH A NAME

    The second basic way to use views is by storing the view in a file with a name
    you choose.  This view can be loaded while editing another file.  Vim will
    then switch to editing the file specified in the view.  Thus you can use this
    to quickly switch to editing another file, with all its options set as you
    saved them.
       For example, to save the view of the current file:

    	:mkview ~/.vim/main.vim

    You can restore it with:

    	:source ~/.vim/main.vim

    ==============================================================================

    *21.6*	Modelines

    When editing a specific file, you might set options specifically for that
    file.  Typing these commands each time is boring.  Using a session or view for
    editing a file doesn't work when sharing the file between several people.
       The solution for this situation is adding a modeline to the file.  This is
    a line of text that tells Vim the values of options, to be used in this file
    only.
       A typical example is a C program where you make indents by a multiple of 4
    spaces.  This requires setting the 'shiftwidth' option to 4.  This modeline
    will do that:

    	/* vim:set shiftwidth=4: */

    Put this line as one of the first or last five lines in the file.  When
    editing the file, you will notice that 'shiftwidth' will have been set to
    four.  When editing another file, it's set back to the default value of eight.
       For some files the modeline fits well in the header, thus it can be put at
    the top of the file.  For text files and other files where the modeline gets
    in the way of the normal contents, put it at the end of the file.

    The 'modelines' option specifies how many lines at the start and end of the
    file are inspected for containing a modeline.  To inspect ten lines:

    	:set modelines=10

    The 'modeline' option can be used to switch this off.  Do this when you are
    working as root on Unix or Administrator on MS-Windows, or when you don't
    trust the files you are editing:

    	:set nomodeline

    Use this format for the modeline:

    	any-text vim:set {option}={value} ... : any-text

    The "any-text" indicates that you can put any text before and after the part
    that Vim will use.  This allows making it look like a comment, like what was
    done above with /* and */.
       The " vim:" part is what makes Vim recognize this line.  There must be
    white space before "vim", or "vim" must be at the start of the line.  Thus
    using something like "gvim:" will not work.
       The part between the colons is a ":set" command.  It works the same way as
    typing the ":set" command, except that you need to insert a backslash before a
    colon (otherwise it would be seen as the end of the modeline).

    Another example:

    	// vim:set textwidth=72 dir=c\:\tmp:  use c:\tmp here

    There is an extra backslash before the first colon, so that it's included in
    the ":set" command.  The text after the second colon is ignored, thus a remark
    can be placed there.

    For more details see |modeline|.

    ==============================================================================

    Next chapter: |usr_22.txt|  Finding the file to edit

    Copyright: see |manual-copyright|  vim:tw=78:ts=8:ft=help:norl:
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