274 lines
12 KiB
Plaintext
274 lines
12 KiB
Plaintext
Hostname: naic.nasa.gov
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Directory path: files/general_info/
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Filename: using-ftp.txt
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Updated: July 12, 1993 (mks)
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USING THE FILE TRANSFER PROTOCOL (FTP)
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======================================
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WHAT IS "FTP"?
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--------------
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FTP (File Transfer Protocol) is the part of the TCP/IP protocol suite
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that helps users move files between systems easily, and can be
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tailored to match the specific types of files involved. If your
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computer uses TCP/IP, you can use FTP. MultiNet users can do
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file transfers too. While some systems look
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different, FTP's functions are standardized, which means you can perform FTP
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transfers between TCP/IP hosts anywhere in the world. Because of this,
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many sites have set up software libraries that are available to all
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network users via anonymous FTP (explained later).
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WHAT CAN FTP DO FOR ME?
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-----------------------
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Since FTP performs an actual login from your host to a remote host,
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you can browse the remote host's files and directories just as if you
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had used TELNET or SET HOST. However, FTP also allows for a special
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type of login, called anonymous FTP. In this case, users do not need
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accounts of their own on a system; instead, they can log into a
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communal account with the userid "anonymous." (In such cases, proper
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"nettiquette" is to provide one's electronic mail address as a
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"password.") Hundreds of sites worldwide support Anonymous FTP
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accounts to distribute information, graphics, and free or low cost
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software. This handout will help you use both "standard" and
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"anonymous" FTP; for more information on available anonymous FTP
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sites, please contact the NAIC (which is itself an anonymous FTP
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site!) at 415-604-0600 or naic@nasa.gov or EAST::"naic@nasa.gov".
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HOW CAN I USE FTP?
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------------------
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To begin a session, you type the FTP command and either the name
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of the host to which you wish to connect, or its IP address.
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(Note that many hosts are case sensitve; for that reason, commands
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are shown here in lowercase. Your host may prefer the initial
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"FTP" command to be in uppercase.)
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For example, to open an FTP connection to the host naic.nasa.gov,
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you would type either
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ftp naic.nasa.gov
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or
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ftp 128.102.128.6
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Once your connection is established, you will be prompted to login.
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If you are connecting to a host on which you have an account, provide
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your userid, either by simply typing it on a Unix system or by typing
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"USER" first on a VMS system. When prompted for your password,
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provide it. If you are connecting to an anonymous FTP host, when
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prompted to log in, use "anonymous" as your user name. When prompted
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for a password, type your electronic mail address or the word "guest."
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Once you have logged in, the system prompt changes to either ftp> or
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the name of the remote host; in either case, you will enter all
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commands at this prompt. Note that online help for FTP commands can
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be obtained by typing help while the FTP prompt is on the screen.
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HOW DO I SEE FILES ON THE REMOTE SYSTEM?
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----------------------------------------
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To see what files and directories are available on the remote system,
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you can use either the DIR or ls commands (some systems only
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understand "ls"; some systems will only understand "dir" in lowercase).
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DIR will get you something like this:
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drwxr-xr-x 2 0 10 512 Apr 13 1989 bin
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drwxr-xr-x 2 14 10 512 Apr 13 1989 etc
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-rw-r--r-- 1 0 0 28503 Sep 10 06:36 ls-lRt
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drwxr-xr-x 14 14 10 1024 Feb 21 14:08 pub
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A "d" in the first column indicates a directory; a dash in the first
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column indicates a file. (When using "ls", you won't get this
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information, but directory names are often followed by a "/".) The
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series of letters and dashes show file protection (Read, Write, and
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eXecute); this is shown rwxrwxrwx for owner, group, and world access;
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you will be able to look at any files/directories with an "r" in the
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last triplet.
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HOW DO I MOVE AROUND ON THE REMOTE SYSTEM?
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------------------------------------------
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This depends a bit on what type of machine the remote host is. For
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the vast majority of systems that support FTP, you simply type "cd"
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and the directory name to move "down" into the named directory, and
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"cd .." (that's two periods) to move back "up" one level in the directory
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hierarchy. You can also immediately zoom up to the FTP login level
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directory (where you started after connecting to the remote host) by
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typing cd /
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Navigation commands differ on VMS systems. You must type
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CD [.directory] to move down and CD [..] to move up (include the
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brackets). Otherwise, the directory navigation commands are pretty
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much universal.
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WHAT KIND OF FILE TRANSFERS CAN I DO WITH FTP?
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----------------------------------------------
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FTP has several commands you may need to use before initiating the
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actual transfer, depending on what type of files are involved. There
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are two basic commands for this: BINARY (or IMAGE) and ASCII.
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The default mode for FTP transfers is ASCII. This works fine for text
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files, but will ruin executables and image files. To successfully
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transfer binaries, you must type the command "binary" (or "bin" or
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"image") at the prompt before initiating the transfer. Similarly,
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text-only files will become "garbage" if they are transferred in
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binary mode. If you want to transfer text after transfering a binary,
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make sure you type "ASCII" first! (See the table at the end of
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this document for a listing of which file types require which FTP
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transfer mode.)
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CAN I FOLLOW THE PROGRESS OF AN FTP TRANSFER?
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---------------------------------------------
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Yes, sort of -- type the command "hash" before initiating a transfer,
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and the system will print a series of pound signs (#) on-screen as the
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transfer runs.
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HOW DO I COPY A FILE FROM THE REMOTE HOST ONTO MY OWN?
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------------------------------------------------------
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To receive, or get, a file from the remote host, you should use the GET
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command; the proper syntax is "get remotefilename targetfilename"
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The target file name refers to the name you want the file to have
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on your local computer, the computer to which the file is moving.
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The target file name is optional; the system will default to the
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original file name if you don't indicate a target file name. This is
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just a handy way of transferring and renaming the file in one step.
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Note: UNIX systems can use multiple periods in a filename (e.g.
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"blah.tar.Z"), but VMS cannot! Make sure the remote file name is
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compatible with your host's operating system! The example below
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copies the file appl.sit.hqx from the remote host, renaming it
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appl.hqx in transit.
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Example: ftp> get appl.sit.hqx appl.hqx
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Beginning ASCII transfer...
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Transfer complete.
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14 bytes transmitted in 1 second. (14 bytes/s)
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CAN I LOOK AT A FILE WITHOUT TRANSFERRING IT FIRST?
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---------------------------------------------------
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FTP allows you to read the contents of text files "on the fly" without
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actually placing a copy of the file on your system by making your
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screen the destination. Although the commands for UNIX and VMS
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systems are similar, there are a few differences.
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On a VMS system, simply type GET filename TT: and the contents of that
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text file will scroll across your screen. NOTE: Be ready to hit
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Control-S or "Hold Screen"; the entire file will scroll by without
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stopping for page breaks!
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On a UNIX system, simply type get filename /dev/tty and the contents
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of that text file will scroll across your screen. If you want the
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display to stop scrolling each time the screen fills, use the command
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get filename |more (some versions of UNIX will use |pg instead); you
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will then be able to read through the text one screen at a time.
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CAN I MOVE A FILE ONTO THE REMOTE HOST?
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---------------------------------------
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The PUT command works just like the GET command (but without the TT:
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trick), complete with the dangers of different operating systems
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having different file naming conventions. Note that the majority of
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anonymous FTP sites will not allow you to put files onto their disks
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without prior permission (and then usually only into specific
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directories). Contact the adminstrator of each specific anonymous
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FTP archive for information on his or her site's policies.
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HEY -- HOW DO I GET OUTTA HERE?!?
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---------------------------------
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To exit from FTP (and log off the remote system), just enter the
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command "bye" or "exit" or "quit" at the prompt (different systems may
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react to only one or the other of these commands, but the results
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will be the same). If you end up looking at the "ftp>" prompt, simply
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enter the same command a second time to return to your normal system
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prompt.
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If you have any questions, please contact the NAIC for more information:
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NASA Network Applications and Information Center
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Ames Research Center
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M/S 233-18
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Moffett Field, CA 93025-1000
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phone: 415-604-0600 fax: 415-604-7300
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naic@nasa.gov EAST::"naic@nasa.gov"
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HOW DO I KNOW WHICH TRANSFER MODE (ASCII OR BINARY) TO USE?
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-----------------------------------------------------------
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The following table describes the most common file types (listed by
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filename extension) and the FTP mode (ASCII or BINARY) you need for a
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successful transfer.
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file type USUALLY means... transfer mode:
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----------- --------------------------------------- ----------------------
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.arc DOS compression format BINARY
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.bak usually a binary backup (depends on system!)
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.bck backup (archived) format BINARY
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binscii Apple II archive format BINARY
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.com VMS command file in DCL ASCII
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.com executable command file in DOS BINARY
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.cpt PackIt archive format (Mac) BINARY
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.dat VMS data files BINARY
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.doc usually ASCII text ASCII
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.dvi special TeX text output format BINARY
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.eps Encapsulated PostScript BINARY
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.exe executable file BINARY
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.gif GIF graphics format BINARY
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.h "include" file for 3GL or 4GL compiler ASCII
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.hlb VMS help libraries BINARY
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.hlp VMS help files ASCII
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.hqx BinHex (ASCII text) format (Macintosh) ASCII
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.jpg JPEG graphics format BINARY
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.lbr very old LU archive format (CP/M) BINARY
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.lis usually text or program listing ASCII
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.lzh Lempel-Ziv compression format BINARY
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.lzw LHWarp archive (Amiga) BINARY
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nupack Apple II archive format BINARY
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.o, .obj compiled (but unlinked) programs BINARY
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.pak "packed" archive format (DOS, OS/2) BINARY
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.pcx PCX graphics format BINARY
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.pict PICT graphics format BINARY
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.pit "packed" archive format (Mac) BINARY
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.pnt MacPaint format BINARY
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.ps postscript format BINARY
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._Q_ "Squeeze" (CP/M) archive BINARY
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.riff RIFF graphics format BINARY
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.rno DEC Standard Runoff format ASCII
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.sea self-extracting archive BINARY
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.shar, .sh UNIX SHell ARchive BINARY
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.sit StuffIt archive format (Mac) BINARY
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.tar UNIX Tape ARchive format BINARY
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.tex TeX formatted text files ASCII
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.text ASCII text ASCII
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.tga Targa graphics format BINARY
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.tiff TIFF graphics format BINARY
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.txt ASCII text ASCII
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.uu, .uue UUencoded archive (UNIX) ASCII
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.wrp Warp archive format (Amiga) BINARY
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.xx, .xxe xxencode format archive (UNIX) ASCII
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.Z UNIX Compress format BINARY
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.zip DOS compression format BINARY
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.zoo ZOO format archive BINARY
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