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+*recover.txt* For Vim version 9.0. Last change: 2020 Aug 15
+
+
+ VIM REFERENCE MANUAL by Bram Moolenaar
+
+
+Recovery after a crash *crash-recovery*
+
+You have spent several hours typing in that text that has to be finished
+next morning, and then disaster strikes: Your computer crashes.
+
+ DON'T PANIC!
+
+You can recover most of your changes from the files that Vim uses to store
+the contents of the file. Mostly you can recover your work with one command:
+ vim -r filename
+
+1. The swap file |swap-file|
+2. Recovery |recovery|
+
+==============================================================================
+1. The swap file *swap-file*
+
+Vim stores the things you changed in a swap file. Using the original file
+you started from plus the swap file you can mostly recover your work.
+
+You can see the name of the current swap file being used with the command:
+
+ :sw[apname] *:sw* *:swapname*
+
+Or you can use the |swapname()| function, which also allows for seeing the
+swap file name of other buffers.
+
+The name of the swap file is normally the same as the file you are editing,
+with the extension ".swp".
+- On Unix, a '.' is prepended to swap file names in the same directory as the
+ edited file. This avoids that the swap file shows up in a directory
+ listing.
+- On MS-Windows machines and when the 'shortname' option is on, any '.' in the
+ original file name is replaced with '_'.
+- If this file already exists (e.g., when you are recovering from a crash) a
+ warning is given and another extension is used, ".swo", ".swn", etc.
+- An existing file will never be overwritten.
+- The swap file is deleted as soon as Vim stops editing the file.
+
+Technical: The replacement of '.' with '_' is done to avoid problems with
+ MS-DOS compatible filesystems (e.g., crossdos, multidos). If Vim
+ is able to detect that the file is on an MS-DOS-like filesystem, a
+ flag is set that has the same effect as the 'shortname' option.
+ This flag is reset when you start editing another file.
+ *E326*
+ If the ".swp" file name already exists, the last character is
+ decremented until there is no file with that name or ".saa" is
+ reached. In the last case, no swap file is created.
+
+By setting the 'directory' option you can place the swap file in another place
+than where the edited file is.
+Advantages:
+- You will not pollute the directories with ".swp" files.
+- When the 'directory' is on another partition, reduce the risk of damaging
+ the file system where the file is (in a crash).
+Disadvantages:
+- You can get name collisions from files with the same name but in different
+ directories (although Vim tries to avoid that by comparing the path name).
+ This will result in bogus ATTENTION warning messages.
+- When you use your home directory, and somebody else tries to edit the same
+ file, that user will not see your swap file and will not get the ATTENTION
+ warning message.
+On the Amiga you can also use a recoverable ram disk, but there is no 100%
+guarantee that this works. Putting swap files in a normal ram disk (like RAM:
+on the Amiga) or in a place that is cleared when rebooting (like /tmp on Unix)
+makes no sense, you will lose the swap file in a crash.
+
+If you want to put swap files in a fixed place, put a command resembling the
+following ones in your .vimrc:
+ :set dir=dh2:tmp (for Amiga)
+ :set dir=~/tmp (for Unix)
+ :set dir=c:\\tmp (for Win32)
+This is also very handy when editing files on floppy. Of course you will have
+to create that "tmp" directory for this to work!
+
+For read-only files, a swap file is not used. Unless the file is big, causing
+the amount of memory used to be higher than given with 'maxmem' or
+'maxmemtot'. And when making a change to a read-only file, the swap file is
+created anyway.
+
+The 'swapfile' option can be reset to avoid creating a swapfile. And the
+|:noswapfile| modifier can be used to not create a swapfile for a new buffer.
+
+:nos[wapfile] {command} *:nos* *:noswapfile*
+ Execute {command}. If it contains a command that loads a new
+ buffer, it will be loaded without creating a swapfile and the
+ 'swapfile' option will be reset. If a buffer already had a
+ swapfile it is not removed and 'swapfile' is not reset.
+
+
+Detecting an existing swap file ~
+
+You can find this in the user manual, section |11.3|.
+
+
+Updating the swapfile ~
+
+The swap file is updated after typing 200 characters or when you have not
+typed anything for four seconds. This only happens if the buffer was
+changed, not when you only moved around. The reason why it is not kept up to
+date all the time is that this would slow down normal work too much. You can
+change the 200 character count with the 'updatecount' option. You can set
+the time with the 'updatetime' option. The time is given in milliseconds.
+After writing to the swap file Vim syncs the file to disk. This takes some
+time, especially on busy Unix systems. If you don't want this you can set the
+'swapsync' option to an empty string. The risk of losing work becomes bigger
+though. On some non-Unix systems (MS-Windows, Amiga) the swap file won't be
+written at all.
+
+If the writing to the swap file is not wanted, it can be switched off by
+setting the 'updatecount' option to 0. The same is done when starting Vim
+with the "-n" option. Writing can be switched back on by setting the
+'updatecount' option to non-zero. Swap files will be created for all buffers
+when doing this. But when setting 'updatecount' to zero, the existing swap
+files will not be removed, it will only affect files that will be opened
+after this.
+
+If you want to make sure that your changes are in the swap file use this
+command:
+
+ *:pre* *:preserve* *E313* *E314*
+:pre[serve] Write all text for the current buffer into its swap
+ file. The original file is no longer needed for
+ recovery. This sets a flag in the current buffer.
+ When the '&' flag is present in 'cpoptions' the swap
+ file will not be deleted for this buffer when Vim
+ exits and the buffer is still loaded |cpo-&|.
+
+A Vim swap file can be recognized by the first six characters: "b0VIM ".
+After that comes the version number, e.g., "3.0".
+
+
+Links and symbolic links ~
+
+On Unix it is possible to have two names for the same file. This can be done
+with hard links and with symbolic links (symlinks).
+
+For hard links Vim does not know the other name of the file. Therefore, the
+name of the swapfile will be based on the name you used to edit the file.
+There is no check for editing the same file by the other name too, because Vim
+cannot find the other swapfile (except for searching all of your harddisk,
+which would be very slow).
+
+For symbolic links Vim resolves the links to find the name of the actual file.
+The swap file name is based on that name. Thus it doesn't matter by what name
+you edit the file, the swap file name will normally be the same. However,
+there are exceptions:
+- When the directory of the actual file is not writable the swapfile is put
+ elsewhere.
+- When the symbolic links somehow create a loop you get an *E773* error
+ message and the unmodified file name will be used. You won't be able to
+ save your file normally.
+
+==============================================================================
+2. Recovery *recovery* *E308* *E311*
+
+Basic file recovery is explained in the user manual: |usr_11.txt|.
+
+Another way to do recovery is to start Vim and use the ":recover" command.
+This is easy when you start Vim to edit a file and you get the "ATTENTION:
+Found a swap file ..." message. In this case the single command ":recover"
+will do the work. You can also give the name of the file or the swap file to
+the recover command:
+ *:rec* *:recover* *E305* *E306* *E307*
+:rec[over] [file] Try to recover [file] from the swap file. If [file]
+ is not given use the file name for the current
+ buffer. The current contents of the buffer are lost.
+ This command fails if the buffer was modified.
+
+:rec[over]! [file] Like ":recover", but any changes in the current
+ buffer are lost.
+
+ *E312* *E309* *E310*
+Vim has some intelligence about what to do if the swap file is corrupt in
+some way. If Vim has doubt about what it found, it will give an error
+message and insert lines with "???" in the text. If you see an error message
+while recovering, search in the file for "???" to see what is wrong. You may
+want to cut and paste to get the text you need.
+
+The most common remark is "???LINES MISSING". This means that Vim cannot read
+the text from the original file. This can happen if the system crashed and
+parts of the original file were not written to disk.
+
+Be sure that the recovery was successful before overwriting the original
+file or deleting the swap file. It is good practice to write the recovered
+file elsewhere and run 'diff' to find out if the changes you want are in the
+recovered file. Or use |:DiffOrig|.
+
+Once you are sure the recovery is ok delete the swap file. Otherwise, you
+will continue to get warning messages that the ".swp" file already exists.
+
+
+
+ENCRYPTION AND THE SWAP FILE *:recover-crypt*
+
+When the text file is encrypted the swap file is encrypted as well. This
+makes recovery a bit more complicated. When recovering from a swap file and
+encryption has been used, you will be asked to enter one or two crypt keys.
+
+If the text file does not exist you will only be asked to enter the crypt key
+for the swap file.
+
+If the text file does exist, it may be encrypted in a different way than the
+swap file. You will be asked for the crypt key twice:
+
+ Need encryption key for "/tmp/tt" ~
+ Enter encryption key: ****** ~
+ "/tmp/tt" [crypted] 23200L, 522129C ~
+ Using swap file "/tmp/.tt.swp" ~
+ Original file "/tmp/tt" ~
+ Swap file is encrypted: "/tmp/.tt.swp" ~
+ If you entered a new crypt key but did not write the text file, ~
+ enter the new crypt key. ~
+ If you wrote the text file after changing the crypt key press enter ~
+ to use the same key for text file and swap file ~
+ Enter encryption key: ~
+
+You can be in one of these two situations:
+
+1. The encryption key was not changed, or after changing the key the text file
+ was written. You will be prompted for the crypt key twice. The second
+ time you can simply press Enter. That means the same key is used for the
+ text file and the swap file.
+2. You entered a new encryption key, but did not save the text file. Vim will
+ then use the new key for the swap file, and the text file will still be
+ encrypted with the old key. At the second prompt enter the new key.
+
+Note that after recovery the key of the swap file will be used for the text
+file. Thus if you write the text file, you need to use that new key.
+
+
+ vim:tw=78:ts=8:noet:ft=help:norl: