codekingpro/portable-devtools

1*usr_23.txt*	For Vim version 9.2.  Last change: 2026 Feb 142 3 4		     VIM USER MANUAL	by Bram Moolenaar5 6 7			     Editing other files8 9 10This chapter is about editing files that are not ordinary files.  With Vim you11can edit files that are compressed or encrypted.  Some files need to be12accessed over the internet.  With some restrictions, binary files can be13edited as well.14 15|23.1|	DOS, Mac and Unix files16|23.2|	Files on the internet17|23.3|	Encryption18|23.4|	Binary files19|23.5|	Compressed files20 21     Next chapter: |usr_24.txt|  Inserting quickly22 Previous chapter: |usr_22.txt|  Finding the file to edit23Table of contents: |usr_toc.txt|24 25==============================================================================26*23.1*	DOS, Mac and Unix files27 28Back in the early days, the old Teletype machines used two characters to29start a new line.  One to move the carriage back to the first position30(carriage return, <CR>), another to move the paper up (line feed, <LF>).31   When computers came out, storage was expensive.  Some people decided that32they did not need two characters for end-of-line.  The UNIX people decided33they could use <New Line> or <NL> only for end-of-line.  The Apple people34standardized on <CR>.  The Microsoft Windows folks decided to keep the old35<CR><NL> (we use <NL> for line feed in the help text).36   This means that if you try to move a file from one system to another, you37have line-break problems.  The Vim editor automatically recognizes the38different file formats and handles things properly behind your back.39   The option 'fileformats' contains the various formats that will be tried40when a new file is edited.  The following command, for example, tells Vim to41try UNIX format first and MS-DOS format second: >42 43	:set fileformats=unix,dos44 45You will notice the format in the message you get when editing a file.  You46don't see anything if you edit a native file format.  Thus editing a Unix file47on Unix won't result in a remark.  But when you edit a dos file, Vim will48notify you of this:49 50	"/tmp/test" [dos] 3L, 71C ~51 52For a Mac file you would see "[mac]".53   The detected file format is stored in the 'fileformat' option.  To see54which format you have, execute the following command: >55 56	:set fileformat?57 58The three names that Vim uses are:59 60	unix		<NL>61	dos		<CR><NL>62	mac		<CR>63 64 65USING THE MAC FORMAT66 67On Unix, <NL> is used to break a line.  It's not unusual to have a <CR>68character halfway a line.  Incidentally, this happens quite often in Vi (and69Vim) scripts.70   On the Macintosh, where <CR> is the line break character, it's possible to71have a <NL> character halfway a line.72   The result is that it's not possible to be 100% sure whether a file73containing both <CR> and <NL> characters is a Mac or a Unix file.  Therefore,74Vim assumes that on Unix you probably won't edit a Mac file, and doesn't check75for this type of file.  To check for this format anyway, add "mac" to76'fileformats': >77 78	:set fileformats+=mac79 80Then Vim will take a guess at the file format.  Watch out for situations where81Vim guesses wrong.82 83 84OVERRULING THE FORMAT85 86If you use the good old Vi and try to edit an MS-DOS format file, you will87find that each line ends with a ^M character.  (^M is <CR>).  The automatic88detection avoids this.  Suppose you do want to edit the file that way?  Then89you need to overrule the format: >90 91	:edit ++ff=unix file.txt92 93The "++" string is an item that tells Vim that an option name follows, which94overrules the default for this single command.  "++ff" is used for95'fileformat'.  You could also use "++ff=mac" or "++ff=dos".96   This doesn't work for any option, only "++ff" and "++enc" are currently97implemented.  The full names "++fileformat" and "++encoding" also work.98 99 100CONVERSION101 102You can use the 'fileformat' option to convert from one file format to103another.  Suppose, for example, that you have an MS-DOS file named README.TXT104that you want to convert to UNIX format.  Start by editing the MS-DOS format105file: >106	vim README.TXT107 108Vim will recognize this as a dos format file.  Now change the file format to109UNIX: >110 111	:set fileformat=unix112	:write113 114The file is written in Unix format.115 116==============================================================================117*23.2*	Files on the internet118 119Someone sends you an e-mail message, which refers to a file by its URL.  For120example:121 122	You can find the information here: ~123		https://ftp.nluug.nl/pub/vim/README124 125You could start a program to download the file, save it on your local disk and126then start Vim to edit it.127   There is a much simpler way.  Move the cursor to any character of the URL.128Then use this command: >129 130	gf131 132With a bit of luck, Vim will figure out which program to use for downloading133the file, download it and edit the copy.  To open the file in a new window use134CTRL-W f.135   If something goes wrong you will get an error message.  It's possible that136the URL is wrong, you don't have permission to read it, the network connection137is down, etc.  Unfortunately, it's hard to tell the cause of the error.  You138might want to try the manual way of downloading the file.139 140Accessing files over the internet works with the netrw plugin.  Currently URLs141with these formats are recognized:142 143	`ftp://`	uses ftp144	`rcp://`	uses rcp145	`scp://`	uses scp146	`http://`	uses wget (reading only)147 148Vim doesn't do the communication itself, it relies on the mentioned programs149to be available on your computer.  On most Unix systems "ftp" and "rcp" will150be present.  "scp" and "wget" might need to be installed.151 152Vim detects these URLs for each command that starts editing a new file, also153with ":edit" and ":split", for example.  Write commands also work, except for154`http://`.155 156For more information, also about passwords, see |netrw|.157 158==============================================================================159*23.3*	Encryption160 161Some information you prefer to keep to yourself.  For example, when writing162a test on a computer that students also use.  You don't want clever students163to figure out a way to read the questions before the exam starts.  Vim can164encrypt the file for you, which gives you some protection.165   To start editing a new file with encryption, use the "-x" argument to start166Vim.  Example: >167 168	vim -x exam.txt169 170Vim prompts you for a key used for encrypting and decrypting the file:171 172	Enter encryption key: ~173 174Carefully type the secret key now.  You cannot see the characters you type,175they will be replaced by stars.  To avoid the situation that a typing mistake176will cause trouble, Vim asks you to enter the key again:177 178	Enter same key again: ~179 180You can now edit this file normally and put in all your secrets.  When you181finish editing the file and tell Vim to exit, the file is encrypted and182written.183   When you edit the file with Vim, it will ask you to enter the same key184again.  You don't need to use the "-x" argument.  You can also use the normal185":edit" command.  Vim adds a magic string to the file by which it recognizes186that the file was encrypted.187   If you try to view this file using another program, all you get is garbage.188Also, if you edit the file with Vim and enter the wrong key, you get garbage.189Vim does not have a mechanism to check if the key is the right one (this makes190it much harder to break the key).191 192 193SWITCHING ENCRYPTION ON AND OFF194 195To disable the encryption of a file, set the 'key' option to an empty string:196>197	:set key=198 199The next time you write the file this will be done without encryption.200   Setting the 'key' option to enable encryption is not a good idea, because201the password appears in the clear.  Anyone shoulder-surfing can read your202password.203   To avoid this problem, the ":X" command was created.  It asks you for an204encryption key, just like the "-x" argument did: >205 206	:X207	Enter encryption key: ******208	Enter same key again: ******209 210 211LIMITS ON ENCRYPTION212 213The encryption algorithm used by Vim is not very strong.  It is good enough to214keep out the casual prowler, but not good enough to keep out a cryptology215expert with lots of time on his hands.  The text in the swap file and the undo216file is also encrypted.  However, this is done block-by-block and may reduce217the time needed to crack a password.  You can disable the swap file, but then218a crash will cause you to lose your work, since Vim keeps all the text in219memory only.  The undo file can be disabled with the only disadvantage that220you can't undo after unloading the buffer.221   To avoid using a swap file, supply the -n argument on the command line.222For example, to edit the encrypted file "file.txt" without a swap file use the223following command: >224 225	vim -x -n file.txt226 227When already editing a file, the swapfile can be disabled with: >228 229	:setlocal noswapfile230 231Since there is no swapfile, recovery will be impossible.  Save the file a bit232more often to avoid the risk of losing your changes.233 234While the file is in memory, it is in plain text.  Anyone with privilege can235look in the editor's memory and discover the contents of the file.236   If you use a viminfo file, be aware that the contents of text registers are237written out in the clear as well.238   If you really want to secure the contents of a file, edit it only on a239portable computer not connected to a network, use good encryption tools, and240keep the computer locked up in a big safe when not in use.241 242==============================================================================243*23.4*	Binary files244 245You can edit binary files with Vim.  Vim wasn't really made for this, thus246there are a few restrictions.  But you can read a file, change a character and247write it back, with the result that only that one character was changed and248the file is identical otherwise.249   To make sure that Vim does not use its clever tricks in the wrong way, add250the "-b" argument when starting Vim: >251 252	vim -b datafile253 254This sets the 'binary' option.  The effect of this is that unexpected side255effects are turned off.  For example, 'textwidth' is set to zero, to avoid256automatic formatting of lines.  And files are always read in Unix file format.257 258Binary mode can be used to change a message in a program.  Be careful not to259insert or delete any characters, it would stop the program from working.  Use260"R" to enter replace mode.261 262Many characters in the file will be unprintable.  To see them in Hex format: >263 264	:set display=uhex265 266Otherwise, the "ga" command can be used to see the value of the character267under the cursor.  The output, when the cursor is on an <Esc>, looks like268this:269 270	<^[>  27,  Hex 1b,  Octal 033 ~271 272There might not be many line breaks in the file.  To get some overview switch273the 'wrap' option off: >274 275	:set nowrap276 277 278BYTE POSITION279 280To see on which byte you are in the file use this command: >281 282	g CTRL-G283 284The output is verbose:285 286    Col 9-16 of 9-16; Line 277 of 330; Word 1806 of 2058; Byte 10580 of 12206 ~287 288The last two numbers are the byte position in the file and the total number of289bytes.  This takes into account how 'fileformat' changes the number of bytes290that a line break uses.291    To move to a specific byte in the file, use the "go" command.  For292example, to move to byte 2345: >293 294	2345go295 296 297USING XXD298 299A real binary editor shows the text in two ways: as it is and in hex format.300You can do this in Vim by first converting the file with the "xxd" program.301This comes with Vim.302   First edit the file in binary mode: >303 304	vim -b datafile305 306Now convert the file to a hex dump with xxd: >307 308	:%!xxd309 310The text will look like this:311 312	0000000: 1f8b 0808 39d7 173b 0203 7474 002b 4e49  ....9..;..tt.+NI ~313	0000010: 4b2c 8660 eb9c ecac c462 eb94 345e 2e30  K,.`.....b..4^.0 ~314	0000020: 373b 2731 0b22 0ca6 c1a2 d669 1035 39d9  7;'1.".....i.59. ~315 316You can now view and edit the text as you like.  Vim treats the information as317ordinary text.  Changing the hex does not cause the printable character to be318changed, or the other way around.319   Finally convert it back with:320>321	:%!xxd -r322 323Only changes in the hex part are used.  Changes in the printable text part on324the right are ignored.325 326See the manual page of xxd for more information.327 328==============================================================================329*23.5*	Compressed files330 331This is easy: You can edit a compressed file just like any other file.  The332"gzip" plugin takes care of decompressing the file when you edit it.  And333compressing it again when you write it.334   These compression methods are currently supported:335 336	.Z	compress337	.gz	gzip338	.bz2	bzip2339 340Vim uses the mentioned programs to do the actual compression and341decompression.  You might need to install the programs first.342 343==============================================================================344 345Next chapter: |usr_24.txt|  Inserting quickly346 347Copyright: see |manual-copyright|  vim:tw=78:ts=8:noet:ft=help:norl:348