1*usr_23.txt* For Vim version 7.3. Last change: 2006 Apr 24 2 3 VIM USER MANUAL - by Bram Moolenaar 4 5 Editing other files 6 7 8This chapter is about editing files that are not ordinary files. With Vim you 9can edit files that are compressed or encrypted. Some files need to be 10accessed over the internet. With some restrictions, binary files can be 11edited as well. 12 13|23.1| DOS, Mac and Unix files 14|23.2| Files on the internet 15|23.3| Encryption 16|23.4| Binary files 17|23.5| Compressed files 18 19 Next chapter: |usr_24.txt| Inserting quickly 20 Previous chapter: |usr_22.txt| Finding the file to edit 21Table of contents: |usr_toc.txt| 22 23============================================================================== 24*23.1* DOS, Mac and Unix files 25 26Back in the early days, the old Teletype machines used two characters to 27start a new line. One to move the carriage back to the first position 28(carriage return, <CR>), another to move the paper up (line feed, <LF>). 29 When computers came out, storage was expensive. Some people decided that 30they did not need two characters for end-of-line. The UNIX people decided 31they could use <Line Feed> only for end-of-line. The Apple people 32standardized on <CR>. The MS-DOS (and Microsoft Windows) folks decided to 33keep the old <CR><LF>. 34 This means that if you try to move a file from one system to another, you 35have line-break problems. The Vim editor automatically recognizes the 36different file formats and handles things properly behind your back. 37 The option 'fileformats' contains the various formats that will be tried 38when a new file is edited. The following command, for example, tells Vim to 39try UNIX format first and MS-DOS format second: > 40 41 :set fileformats=unix,dos 42 43You will notice the format in the message you get when editing a file. You 44don't see anything if you edit a native file format. Thus editing a Unix file 45on Unix won't result in a remark. But when you edit a dos file, Vim will 46notify you of this: 47 48 "/tmp/test" [dos] 3L, 71C ~ 49 50For a Mac file you would see "[mac]". 51 The detected file format is stored in the 'fileformat' option. To see 52which format you have, execute the following command: > 53 54 :set fileformat? 55 56The three names that Vim uses are: 57 58 unix <LF> 59 dos <CR><LF> 60 mac <CR> 61 62 63USING THE MAC FORMAT 64 65On Unix, <LF> is used to break a line. It's not unusual to have a <CR> 66character halfway a line. Incidentally, this happens quite often in Vi (and 67Vim) scripts. 68 On the Macintosh, where <CR> is the line break character, it's possible to 69have a <LF> character halfway a line. 70 The result is that it's not possible to be 100% sure whether a file 71containing both <CR> and <LF> characters is a Mac or a Unix file. Therefore, 72Vim assumes that on Unix you probably won't edit a Mac file, and doesn't check 73for this type of file. To check for this format anyway, add "mac" to 74'fileformats': > 75 76 :set fileformats+=mac 77 78Then Vim will take a guess at the file format. Watch out for situations where 79Vim guesses wrong. 80 81 82OVERRULING THE FORMAT 83 84If you use the good old Vi and try to edit an MS-DOS format file, you will 85find that each line ends with a ^M character. (^M is <CR>). The automatic 86detection avoids this. Suppose you do want to edit the file that way? Then 87you need to overrule the format: > 88 89 :edit ++ff=unix file.txt 90 91The "++" string is an item that tells Vim that an option name follows, which 92overrules the default for this single command. "++ff" is used for 93'fileformat'. You could also use "++ff=mac" or "++ff=dos". 94 This doesn't work for any option, only "++ff" and "++enc" are currently 95implemented. The full names "++fileformat" and "++encoding" also work. 96 97 98CONVERSION 99 100You can use the 'fileformat' option to convert from one file format to 101another. Suppose, for example, that you have an MS-DOS file named README.TXT 102that you want to convert to UNIX format. Start by editing the MS-DOS format 103file: > 104 vim README.TXT 105 106Vim will recognize this as a dos format file. Now change the file format to 107UNIX: > 108 109 :set fileformat=unix 110 :write 111 112The file is written in Unix format. 113 114============================================================================== 115*23.2* Files on the internet 116 117Someone sends you an e-mail message, which refers to a file by its URL. For 118example: 119 120 You can find the information here: ~ 121 ftp://ftp.vim.org/pub/vim/README ~ 122 123You could start a program to download the file, save it on your local disk and 124then start Vim to edit it. 125 There is a much simpler way. Move the cursor to any character of the URL. 126Then use this command: > 127 128 gf 129 130With a bit of luck, Vim will figure out which program to use for downloading 131the file, download it and edit the copy. To open the file in a new window use 132CTRL-W f. 133 If something goes wrong you will get an error message. It's possible that 134the URL is wrong, you don't have permission to read it, the network connection 135is down, etc. Unfortunately, it's hard to tell the cause of the error. You 136might want to try the manual way of downloading the file. 137 138Accessing files over the internet works with the netrw plugin. Currently URLs 139with these formats are recognized: 140 141 ftp:// uses ftp 142 rcp:// uses rcp 143 scp:// uses scp 144 http:// uses wget (reading only) 145 146Vim doesn't do the communication itself, it relies on the mentioned programs 147to be available on your computer. On most Unix systems "ftp" and "rcp" will 148be present. "scp" and "wget" might need to be installed. 149 150Vim detects these URLs for each command that starts editing a new file, also 151with ":edit" and ":split", for example. Write commands also work, except for 152http://. 153 154For more information, also about passwords, see |netrw|. 155 156============================================================================== 157*23.3* Encryption 158 159Some information you prefer to keep to yourself. For example, when writing 160a test on a computer that students also use. You don't want clever students 161to figure out a way to read the questions before the exam starts. Vim can 162encrypt the file for you, which gives you some protection. 163 To start editing a new file with encryption, use the "-x" argument to start 164Vim. Example: > 165 166 vim -x exam.txt 167 168Vim prompts you for a key used for encrypting and decrypting the file: 169 170 Enter encryption key: ~ 171 172Carefully type the secret key now. You cannot see the characters you type, 173they will be replaced by stars. To avoid the situation that a typing mistake 174will cause trouble, Vim asks you to enter the key again: 175 176 Enter same key again: ~ 177 178You can now edit this file normally and put in all your secrets. When you 179finish editing the file and tell Vim to exit, the file is encrypted and 180written. 181 When you edit the file with Vim, it will ask you to enter the same key 182again. You don't need to use the "-x" argument. You can also use the normal 183":edit" command. Vim adds a magic string to the file by which it recognizes 184that the file was encrypted. 185 If you try to view this file using another program, all you get is garbage. 186Also, if you edit the file with Vim and enter the wrong key, you get garbage. 187Vim does not have a mechanism to check if the key is the right one (this makes 188it much harder to break the key). 189 190 191SWITCHING ENCRYPTION ON AND OFF 192 193To disable the encryption of a file, set the 'key' option to an empty string: 194> 195 :set key= 196 197The next time you write the file this will be done without encryption. 198 Setting the 'key' option to enable encryption is not a good idea, because 199the password appears in the clear. Anyone shoulder-surfing can read your 200password. 201 To avoid this problem, the ":X" command was created. It asks you for an 202encryption key, just like the "-x" argument did: > 203 204 :X 205 Enter encryption key: ****** 206 Enter same key again: ****** 207 208 209LIMITS ON ENCRYPTION 210 211The encryption algorithm used by Vim is weak. It is good enough to keep out 212the casual prowler, but not good enough to keep out a cryptology expert with 213lots of time on his hands. Also you should be aware that the swap file is not 214encrypted; so while you are editing, people with superuser privileges can read 215the unencrypted text from this file. 216 One way to avoid letting people read your swap file is to avoid using one. 217If the -n argument is supplied on the command line, no swap file is used 218(instead, Vim puts everything in memory). For example, to edit the encrypted 219file "file.txt" without a swap file use the following command: > 220 221 vim -x -n file.txt 222 223When already editing a file, the swapfile can be disabled with: > 224 225 :setlocal noswapfile 226 227Since there is no swapfile, recovery will be impossible. Save the file a bit 228more often to avoid the risk of losing your changes. 229 230While the file is in memory, it is in plain text. Anyone with privilege can 231look in the editor's memory and discover the contents of the file. 232 If you use a viminfo file, be aware that the contents of text registers are 233written out in the clear as well. 234 If you really want to secure the contents of a file, edit it only on a 235portable computer not connected to a network, use good encryption tools, and 236keep the computer locked up in a big safe when not in use. 237 238============================================================================== 239*23.4* Binary files 240 241You can edit binary files with Vim. Vim wasn't really made for this, thus 242there are a few restrictions. But you can read a file, change a character and 243write it back, with the result that only that one character was changed and 244the file is identical otherwise. 245 To make sure that Vim does not use its clever tricks in the wrong way, add 246the "-b" argument when starting Vim: > 247 248 vim -b datafile 249 250This sets the 'binary' option. The effect of this is that unexpected side 251effects are turned off. For example, 'textwidth' is set to zero, to avoid 252automatic formatting of lines. And files are always read in Unix file format. 253 254Binary mode can be used to change a message in a program. Be careful not to 255insert or delete any characters, it would stop the program from working. Use 256"R" to enter replace mode. 257 258Many characters in the file will be unprintable. To see them in Hex format: > 259 260 :set display=uhex 261 262Otherwise, the "ga" command can be used to see the value of the character 263under the cursor. The output, when the cursor is on an <Esc>, looks like 264this: 265 266 <^[> 27, Hex 1b, Octal 033 ~ 267 268There might not be many line breaks in the file. To get some overview switch 269the 'wrap' option off: > 270 271 :set nowrap 272 273 274BYTE POSITION 275 276To see on which byte you are in the file use this command: > 277 278 g CTRL-G 279 280The output is verbose: 281 282 Col 9-16 of 9-16; Line 277 of 330; Word 1806 of 2058; Byte 10580 of 12206 ~ 283 284The last two numbers are the byte position in the file and the total number of 285bytes. This takes into account how 'fileformat' changes the number of bytes 286that a line break uses. 287 To move to a specific byte in the file, use the "go" command. For 288example, to move to byte 2345: > 289 290 2345go 291 292 293USING XXD 294 295A real binary editor shows the text in two ways: as it is and in hex format. 296You can do this in Vim by first converting the file with the "xxd" program. 297This comes with Vim. 298 First edit the file in binary mode: > 299 300 vim -b datafile 301 302Now convert the file to a hex dump with xxd: > 303 304 :%!xxd 305 306The text will look like this: 307 308 0000000: 1f8b 0808 39d7 173b 0203 7474 002b 4e49 ....9..;..tt.+NI ~ 309 0000010: 4b2c 8660 eb9c ecac c462 eb94 345e 2e30 K,.`.....b..4^.0 ~ 310 0000020: 373b 2731 0b22 0ca6 c1a2 d669 1035 39d9 7;'1.".....i.59. ~ 311 312You can now view and edit the text as you like. Vim treats the information as 313ordinary text. Changing the hex does not cause the printable character to be 314changed, or the other way around. 315 Finally convert it back with: 316> 317 :%!xxd -r 318 319Only changes in the hex part are used. Changes in the printable text part on 320the right are ignored. 321 322See the manual page of xxd for more information. 323 324============================================================================== 325*23.5* Compressed files 326 327This is easy: You can edit a compressed file just like any other file. The 328"gzip" plugin takes care of decompressing the file when you edit it. And 329compressing it again when you write it. 330 These compression methods are currently supported: 331 332 .Z compress 333 .gz gzip 334 .bz2 bzip2 335 336Vim uses the mentioned programs to do the actual compression and 337decompression. You might need to install the programs first. 338 339============================================================================== 340 341Next chapter: |usr_24.txt| Inserting quickly 342 343Copyright: see |manual-copyright| vim:tw=78:ts=8:ft=help:norl: 344