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-
-
-
-From VMS to Linux HOWTO
-
-
-
-----
-
-!!!From VMS to Linux HOWTO
-
-!!By Guido Gonzato,
-guido ``at'' ibogeo.df.unibo.it,
-and Mike Miller,
-miller5@uiuc.eduv1.1.3, 17 September 1999
-
-
-----
-''This HOWTO is aimed at all those who have been using VMS and now need or
-want to switch to Linux, the free UNIX clone. The transition is made
-(hopefully) painless with a step--to--step comparison between commands and
-available tools.''
-----
-
-
-
-
-!!1. Introduction
-
-
-****1.1 Why Linux?
-
-****1.2 Comparing Commands and Files
-
-
-
-
-
-!!2. Short Intro
-
-
-****2.1 Files
-
-****2.2 Directories
-
-****2.3 Programs
-
-****2.4 Quick Tour
-
-
-
-
-
-!!3. Editing Files
-
-
-
-
-!!4. !TeXing
-
-
-
-
-!!5. Programming
-
-
-****5.1 Fortran
-
-****5.2 Using make
-
-****5.3 Shell Scripts
-
-****5.4 C
-
-
-
-
-
-!!6. Graphics
-
-
-
-
-!!7. Mail and Internet Tools
-
-
-
-
-!!8. Advanced Topics
-
-
-****8.1 Permissions and Ownership
-
-****8.2 Multitasking: Processes and Jobs
-
-****8.3 Files, Revisited
-
-****8.4 Print Queues
-
-
-
-
-
-!!9. Configuring
-
-
-
-
-!!10. Useful Programs
-
-
-****10.1 Browsing Files: less
-
-****10.2 Numbered Backups Under Linux
-
-****10.3 Archiving: tar & gzip
-
-
-
-
-
-!!11. Real Life Examples
-
-
-
-
-!!12. Tips You Can't Do Without
-
-
-
-
-!!13. Reading VMS tapes from Linux
-
-
-****13.1 Introduction
-
-****13.2 The Basics
-
-****13.3 Some details
-
-****13.4 Comment on Block Size
-
-
-
-
-
-!!14. The End
-
-
-****14.1 Copyright
-
-****14.2 Disclaimer
-
-----
-
-!! 1. Introduction
-
-!!1.1 Why Linux?
-
-
-
-
-
-
-You've heard that UNIX is difficult and balk at the prospect of leaving VMS,
-don't you? Don't worry. Linux, one of the finest UNIX clones, is not more
-difficult to use than VMS; actually, I find it easier. Although VMS
-aficionados may not agree, in many people's opinion Linux is much more
-powerful and versatile.
-
-
-Linux and VMS are both good operating systems and accomplish essentially the
-same tasks, but Linux has a few features that make it a good alternative to
-VMS. Moreover, Linux is available for PCs while VMS is not, and modern
-Pentium-based Linux machines can outperform a VAX. The icing on the cake is
-the excellent performance of modern video cards, which turn an X11-based
-Linux box into a fast graphic workstation; nearly always, quicker than
-dedicated machines.
-
-
-I imagine you're a university researcher or a student, and that you use
-VMS for the following everyday tasks:
-
-
-
-
-
-**** writing papers with TeX/LaTeX;
-****
-
-**** programming in Fortran;
-****
-
-**** doing some graphics;
-****
-
-**** using Internet services;
-****
-
-**** et cetera.
-
-****
-
-
-
-In the following sections I'm going to explain to you how to do these
-tasks under Linux, exploiting your experience with VMS. Prerequisites:
-
-
-
-
-
-**** Linux and X Window System are properly installed;
-
-****
-
-**** there's a system administrator to take care of the technical
-details (please get help from them, not from me ;-) ;
-
-****
-
-**** your shell---the equivalent of DCL---is bash (ask your
-sysadm).
-
-****
-
-
-
-Please note that this HOWTO is not enough to acquaint you fully with
-Linux: it only contains the bare essential to get you started. You
-should learn more about Linux to make the most of it (advanced bash
-features, programming, regular expressions...). From now on, RMP means
-`please read the man pages for further details'. The man pages are the
-equivalent of the command HELP.
-
-
-The Linux Documentation Project documents, available on
-ftp://sunsite.unc.edu:/pub/Linux/docs/LDP, are an important source of
-information. I suggest that you read Larry Greenfield's ``Linux User
-Guide''---it's invaluable for the novice user.
-
-
-And now, go ahead.
-
-
-
-
-!!1.2 Comparing Commands and Files
-
-
-
-
-
-
-This table attempts to compare VMS' and Linux' most used commands. Please
-keep in mind that the syntax is often very different; for more details,
-refer to the following sections.
-
-
-
-
-
-VMS Linux Notes
-------------------------------------------------------------------------------
-@COMMAND command must be executable
-COPY file1 file2 cp file1 file2
-CREATE/DIR
[[.dirname
] mkdir dirname only one at a time
-CREATE/DIR [[.dir1.dir2] mkdirhier dir/name
-DELETE filename rm filename
-DIFF file1 file2 diff -c file1 file2
-DIRECTORY ls
-DIRECTORY [[...]file find . -name file
-DIRECTORY/FULL ls -al
-EDIT filename vi filename, you won't like it
-emacs filename, EDT compatible
-jed filename ditto---my favourite
-FORTRAN prog.for g77 prog.f, no need to do LINK
-f77 prog.f,
-fort77 prog.f
-HELP command man command must specify `command'
-info command ditto
-LATEX file.tex latex file.tex
-LOGIN.COM .bash_profile, `hidden' file
-.bashrc ditto
-LOGOUT.COM .bash_logout ditto
-MAIL mail, crude
-elm, much better
-pine better still
-PRINT file.ps lpr file.ps
-PRINT/QUEUE=laser file.ps lpr -Plaser file.ps
-PHONE user talk user
-RENAME file1 file2 mv file1 file2 not for multiple files
-RUN progname progname
-SEARCH file "pattern" grep pattern file
-SET DEFAULT [[-] cd ..
-SET DEFAULT [[.dir.name] cd dir/name
-SET HOST hostname telnet hostname, not exactly the same
-rlogin hostname
-SET FILE/OWNER_UIC=joe chown joe file completely different
-SET NOBROADCAST mesg
-SET PASSWORD passwd
-SET PROT=(perm) file chmod perm file completely different
-SET TERMINAL export TERM= different syntax
-SHOW DEFAULT pwd
-SHOW DEVICE du, df
-SHOW ENTRY lpq
-SHOW PROCESS ps -ax
-SHOW QUEUE lpq
-SHOW SYSTEM top
-SHOW TIME date
-SHOW USERS w
-STOP kill
-STOP/QUEUE kill, for processes
-lprm for print queues
-SUBMIT command command &
-SUBMIT/AFTER=time command at time command
-TEX file.tex tex file.tex
-TYPE/PAGE file more file
-less file much better
-
-
-
-
-But of course it's not only a matter of different command names. Read on.
-
-
-
-
-
-
-----
-
-!! 2. Short Intro
-
-
-
-
-
-This is what you absolutely need to know before logging in the first
-time. Relax, it's not much.
-
-
-
-
-!!2.1 Files
-
-
-
-
-
-
-
-
-
-**** Under VMS filenames are in the form filename.extension;version.
-Under Linux, the version number doesn't exist (big limitation, but see
-Section
-Numbered Backups Under Linux); the filename
-has normally a limit of 255 characters and can have as many dots as you
-like. Example of filename: This.is_a_FILEname.txt.
-
-****
-
-**** Linux distinguishes between upper case and lower case characters:
-FILENAME.txt and filename.txt are two different files;
-ls is a command, LS is not.
-
-****
-
-**** A filename starting with a dot is a `hidden' file (that is,
-it won't normally show up in dir listings), while filenames ending with a
-tilde '~' represent backup files.
-
-****
-
-
-
-Now, a table to sum up how to translate commands from VMS to Linux:
-
-
-
-
-
-VMS Linux
----------------------------------------------------------------------
-$ COPY file1.txt file2.txt $ cp file1.txt file2.txt
-$ COPY [[.dir]file.txt [[] $ cp dir/file.txt .
-$ COPY [[.dir]file.txt [[-] $ cp dir/file.txt ..
-$ DELETE *.dat;* $ rm *dat
-$ DIFF file1 file2 $ diff -c file1 file2
-$ PRINT file $ lpr file
-$ PRINT/queue=queuename file $ lpr -Pprintername file
-$ SEARCH *.tex;* "geology" $ grep geology *tex
-
-
-
-
-For other examples involving directories, see below; for details about
-protections, ownership, and advanced topics, see Section
-Advanced Topics.
-
-
-
-
-!!2.2 Directories
-
-
-
-
-
-
-
-
-
-**** Within the same node and device, directories names under VMS are in
-the form [[top.dir.subdir]; under Linux, /top/dir/subdir/. On
-the top of the directory tree lies the so--called `root directory' called
-/; underneath there are other directories like /bin,
-/usr, /tmp, /etc, and others.
-
-****
-
-**** The directory /home contains the so--called users' `home
-directories': e.g. /home/guido, /home/warner, and so on.
-When a user logs in, they start working in their home dir; it's the
-equivalent of SYS$LOGIN. There's a shortcut for the home
-directory: the tilde '~'. So, cd ~/tmp is the same
-as, say, cd /home/guido/tmp.
-
-****
-
-**** Directory names follow the same rules as file names. Furthermore,
-each directory has two special entries: one is . and refers to the
-directory itself (like [[]), and .. that refers to the parent
-directory (like [[-]).
-
-****
-
-
-
-And now for some other examples:
-
-
-
-
-
-VMS Linux
----------------------------------------------------------------------
-$ CREATE/DIR [[.dirname] $ mkdir dirname
-$ CREATE/DIR [[.dir1.dir2.dir3] $ mkdirhier dir1/dir2/dir3
-n/a $ rmdir dirname
-(if dirname is empty)
-$ rm -R dirname
-$ DIRECTORY $ ls
-$ DIRECTORY [[...]file.*;* $ find . -name "file*"
-$ SET DEF SYS$LOGIN $ cd
-$ SET DEF [[-] $ cd ..
-$ SET DEF [[top.dir.subdir] $ cd /top/dir/subdir
-$ SET DEF [[.dir.subdir] $ cd dir/subdir
-$ SHOW DEF $ pwd
-
-
-
-
-For protections, ownership, and advanced topics, see Section
-Advanced Topics.
-
-
-
-
-!!2.3 Programs
-
-
-
-
-
-
-
-
-
-**** Commands, compiled programs, and shell scripts (VMS' `command
-files') don't have sort of mandatory extensions like .EXE or .COM
-and can be called whatever you like. Executable files are marked by an
-asterisk '*' when you issue ls -F.
-
-****
-
-**** To run an executable file, just type its name (no RUN
-PROGRAM.EXE or @COMMAND). Caveat: it's essential that the file be
-located in a directory included in the ''path of executables'', which is a
-list of directories. Typically, the path includes dirs like /bin,
-/usr/bin, /usr/X11R6/bin, and others. If you write your
-own programs, put them in a directory you have included in the path (see how
-in Section
-Configuring). As an alternative,
-you may run a program specifying its complete path: e.g.,
-/home/guido/data/myprog; or ./myprog, if the current
-directory isn't in the path.
-
-****
-
-**** Command switches are obtained with /OPTION= under VMS, and
-with -switch or --switch under Linux, where switch is a
-letter, more letters combined, or a word. In particular, the switch -R
-(recursive) of many Linux commands performs the same action as [[...]
-under VMS;
-
-****
-
-**** You can issue several commands on the command line:
-
-
-$ command1 ; command2 ; ... ; commandn
-
-
-
-****
-
-**** Most of the flexibility of Linux comes from two features awkwardly
-implemented or missing in VMS: I/O redirection and piping. (I have been told
-that recent versions of DCL support redirection and piping, but I don't have
-that version.) Redirection is a side feature under VMS (remember
-the switch /OUTPUT= of many commands), or a fastidious process,
-like:
-
-
-$ DEFINE /USER SYS$OUTPUT OUT
-$ DEFINE /USER SYS$INPUT IN
-$ RUN PROG
-
-
-which has the simple Linux (UNIX) equivalent:
-
-
-$ prog < in > out
-
-
-Piping is not readily available under VMS, but has a key role under UNIX. A
-typical example:
-
-
-$ myprog < datafile | filter_1 | filter_2 >> result.dat 2> errors.log &
-
-
-which means: the program myprog gets its input from the file
-datafile (via <), its output is piped (via |) to
-the program filter_1 that takes it as input and processes it, the
-resulting output is piped again to filter_2 for further processing, the
-final output is appended (via >>) to the file result.dat,
-and error messages are redirected (via 2>) onto the file
-errors.log. All this in background (& at the end of the
-command line). More about this in Section
-Examples.
-
-****
-
-
-
-For multitasking, `queues', and the like, see Section
-Advanced Topics.
-
-
-
-
-!! 2.4 Quick Tour
-
-
-
-
-
-
-Now you are ready to try Linux out. Enter your login name and password
-''exactly'' as they are. For example, if your login name and password are
-john and My_!PassWd, ''don't'' type John or my_passwd.
-Remember, UNIX distinguishes between capital and small letters.
-
-
-Once you've logged in, you'll see a prompt; chances are it'll be something
-like machinename:$. If you want to change the prompt or make
-some programs start automatically, you'll have to edit a `hidden' file
-called .profile or .bash_profile (see example in Section
-Configuring). This is the equivalent of
-LOGIN.COM.
-
-
-Pressing ALT--F1, ALT--F2, ... ALT--F6 switches between `virtual consoles'.
-When one VC is busy with a full--screen application, you can flip over to
-another and continue to work. Try and log in to another VC.
-
-
-Now you may want to start X Window System (from now on, X). X is a graphic
-environment very similar to DECWindows---actually, the latter derives from
-the former. Type the command startx and wait a few seconds; most likely
-you'll see an open xterm or equivalent terminal emulator, and possibly
-a button bar. (It depends on how your sysadm configured your Linux box.)
-Click on the desktop (try both mouse buttons) to see a menu.
-
-
-While in X, to access the text mode (`console') sessions press
-CTRL--ALT--F1 ... CTRL--ALT--F6. Try it. When in console, go back to X
-pressing ALT--F7. To quit X, follow the menu instructions or press
-CTRL--ALT--BS.
-
-
-Type the following command to list your home dir contents, including the
-hidden files:
-
-
-
-
-
-$ ls -al
-
-
-
-
-Press SHIFT--PAG UP to back-scroll. Now get help about the ls command
-typing:
-
-
-
-
-
-$ man ls
-
-
-
-
-pressing 'q' to exit. To end the tour, type exit to quit your session.
-If now you want to turn off your PC, press CTRL--ALT--DEL and wait a few
-seconds (''never'' switch off the PC while in Linux! You could damage the
-filesystem.)
-
-
-If you think you're ready to work, go ahead, but if I were you I'd jump
-to Section
-Advanced Topics.
-
-
-
-
-
-
-----
-
-!! 3. Editing Files
-
-
-
-
-
-Linux doesn't have EDT, but there are scores of editors available. The
-only one that's guaranteed to be included in every UNIX version is
-vi---forget it, your sysadm must have installed something better.
-Probably the most popular editor is emacs, which can emulate EDT
-to a certain degree; jed is another editor that provides EDT
-emulation.
-
-
-These two editors are particularly useful for editing program sources, since
-they have two features unknown to EDT: syntax hilighting and automatic
-indentation. Moreover, you can compile your programs from within the editor
-(command ESC-X compile); in case of a syntax error, the cursor will be
-positioned on the offending line. I bet that you'll never want to use the
-true blue EDT again.
-
-
-If you have emacs: start it, then type ESC-X edt-emulation-on.
-Pressing ALT--X or ESC-X is emacs' way of issuing commands, like
-EDT's CTRL--Z. From now on, emacs acts like EDT apart from a
-few commands. Differences:
-
-
-
-
-
-**** ''don't'' press CTRL--Z to issue commands (if you did, you stopped
-emacs. Type fg to resume it);
-
-****
-
-**** there's an extensive on-line help. Press CTRL-H ?, or CTRL-H T to
-start a tutorial;
-
-****
-
-**** to save a file, press CTRL-X CTRL-S;
-
-****
-
-**** to exit, press CTRL-X CTRL-C;
-
-****
-
-**** to insert a new file in a buffer, press CTRL-X CTRL-F, then
-CTRL-X B to switch among buffers.
-
-****
-
-
-
-If you have jed: ask your sysadm to configure jed properly.
-Emulation is already on when you start it; use the normal keypad keys, and
-press CTRL--H CTRL--H or CTRL-? to get help. Commands are issued in the same
-way as emacs'. In addition, there are some handy key bindings missing
-in the original EDT; key bindings can also be tailored to your own
-taste. Ask your sysadm.
-
-
-In alternative, you may use another editor with a completely different
-interface. emacs in native mode is an obvious choice; another popular
-editor is joe, which can emulate other editors like emacs itself
-(being even easier to use) or the DOS editor. Invoke the editor as
-jmacs or jstar and press, respectively, CTRL-X H or CTRL-J to get
-online help. emacs and jed are ''much'' more powerful than good
-ol' EDT.
-
-
-
-
-
-
-----
-
-!! 4. !TeXing
-
-
-
-
-
-TeX and LaTeX are identical to their VMS counterparts---only quicker :-),
-but the tools to handle the .dvi and .ps files are superior:
-
-
-
-
-
-**** to run a TeX file through TeX, do as usual: tex file.tex;
-
-****
-
-**** to turn a .dvi file into a .ps file, type
-dvips -o filename.ps filename.dvi;
-
-****
-
-**** to visualize a .dvi file, type within an X session:
-xdvi filename.dvi &. Click on the page to magnify. This program
-is smart: if you edit and run TeX producing newer versions of the .dvi
-file, xdvi will update it automatically;
-
-****
-
-**** to visualize a .ps file, type within an X session: ghostview
-filename.ps &. Click on the page to magnify. The whole document or
-selected pages can be printed. A newer and better program is gv.
-
-****
-
-**** to print the .ps: usually the command lpr mypaper.ps will
-do, but if the !PostScript printer is called, say, `ps' (ask your
-sysadm) you'll do: lpr -Pps mypaper.ps. For more information
-about print queues, go to Section
-Print Queues.
-
-****
-
-
-
-
-
-
-
-----
-
-!! 5. Programming
-
-
-
-
-
-Programming under Linux is ''much'' better: there are lots of tools that
-make programming easier and quicker. For instance, the drudgery of
-editing--saving--exiting--compiling--re-editing can be cut short by using
-editors like emacs or jed, as seen above.
-
-
-
-
-!!5.1 Fortran
-
-
-
-
-
-
-Not substantial differences
here, but note that at the time of writing the
-available (free) compilers are not 100% compatible with VMS'; expect
-some minor quirks. (It's actually the VMS compiler which has non-standard
-extensions.) See /usr/doc/g77/DOC or /usr/doc/f2c/f2c.ps
-for details.
-
-
-Your sysadm has installed a native compiler called g77 (good but, as of
-version .5.21, still not perfectly compatible with DEC Fortran) or possibly
-the Fortran to C translator, f2c, and one of the front-ends that make it
-mimic a native compiler. In my experience, the package yaf77 is the
-one that provides best results.
-
-
-To compile a Fortran program with g77, edit the source, save it with
-extension .f, then do:
-
-
-
-
-
-$ g77 myprog.f
-
-
-
-
-which creates by default an executable called a.out (you don't have
-to link anything). To give the executable a different name and do some
-optimisation:
-
-
-
-
-
-$ g77 -O2 -o myprog myprog.f
-
-
-
-
-Beware of optimisations! Ask your sysadm to read the documentation that
-comes with the compiler and tell you if there are any problems.
-
-
-To compile a subroutine:
-
-
-
-
-
-$ g77 -c mysub.f
-
-
-
-
-This creates a file mysub.o. To link this subroutine to a program,
-you'll do
-
-
-
-
-
-$ g77 -o myprog myprog.f mysub.o
-
-
-
-
-If you have many external subroutines and you want to make a library, do the
-following:
-
-
-
-
-
-$ cd subroutines/
-$ cat *f >mylib.f ; g77 -c mylib.f
-
-
-
-
-This will create mylib.o that you can link to your programs.
-
-
-Finally, to link an external library called, say, libdummy.so:
-
-
-
-
-
-$ g77 -o myprog myprog.f -ldummy
-
-
-
-
-If you have f2c, you only have to use f77 or fort77 instead
-of g77.
-
-
-Another useful programming tool is make, described below.
-
-
-
-
-
-
-
-!!5.2 Using make
-
-
-
-
-
-
-The utility make is a tool to handle the compilation of programs that
-are split into several source files. The VMS counterparts are MMS
-and MMK, which have a different syntax.
-
-
-Let's suppose you have source files containing your routines, file_1.f,
-file_2.f, file_3.f, and a source file of the main program that uses the
-routines, myprog.f. If you compile your program manually, whenever you
-modify one of the source files you have to figure out which file depends on
-which, which file to recompile first, and so on.
-
-
-Instead of getting mad, you can write a `makefile'. This is a text file
-containing the dependencies between your sources: when one is modified, only
-the ones that depend on the modified file will be recompiled.
-
-
-In our example, you'd write a makefile like this:
-
-
-
-----
-
-# This is makefile
-# Press the <TAB> key where you see <TAB>!
-# It's important: don't use spaces instead.
-myprog: myprog.o file_1.o file_2.o file_3.o
-<TAB>g77 -o myprog myprog.o file_1.o file_2.o file_3.o
-# myprog depends on four object files
-myprog.o: myprog.f
-<TAB>g77 -c myprog.f
-# myprog.o depends on its source file
-file_1.o: file_1.f
-<TAB>g77 -c file_1.f
-# file_1.o depends on its source file
-file_2.o: file_2.f file_1.o
-<TAB>g77 -c file_2.f file_1.o
-# file_2.o depends on its source file and an object file
-file_3.o: file_3.f file_2.o
-<TAB>g77 -c file_3.f file_2.o
-# file_3.o depends on its source file and an object file
-# end of makefile.
-
-----
-
-
-Save this file as Makefile and type make to compile your program;
-alternatively, save it as myprog.mak and type make -f myprog.mak.
-And of course, RMP.
-
-
-
-
-
-
-
-!!5.3 Shell Scripts
-
-
-
-
-
-
-Shell scripts are the equivalent of VMS' command files, and allow for very
-powerful constructs.
-
-
-To write a script, all you have to do is write a standard ASCII file
-containing the commands, save it, then make it executable with the
-command chmod +x <scriptfile>. To execute it, type its name.
-
-
-Writing scripts under bash is such a vast subject it would require a
-book by itself, and I will not delve into the topic any further. I'll just
-give you a more-or-less comprehensive and (hopefully) useful example you can
-extract some basic rules from.
-
-
-EXAMPLE: sample.sh
-
-
-
-----
-
-#!/bin/sh
-# sample.sh
-# I am a comment
-# don't change the first line, it must be there
-echo "This system is: `uname -a`" # use the output of the command
-echo "My name is $" # built-in variables
-echo "You gave me the following $# parameters: "$*
-echo "First parameter is: "$1
-echo -n "What's your name? " ; read your_name
-echo notice the difference: "hi $your_name" # quoting with "
-echo notice the difference: 'hi $your_name' # quoting with '
-DIRS=0 ; FILES=
-for file in `ls .` ; do
-if [[ -d ${file} ] ; then # if file is a directory
-DIRS=`expr $DIRS + 1` # this means DIRS = DIRS + 1
-elif [[ -f ${file} ] ; then
-FILES=`expr $FILES + 1`
-fi
-case ${file} in
-*.gif|*jpg) echo "${file}: graphic file" ;;
-*.txt|*.tex) echo "${file}: text file" ;;
-*.c|*.f|*.for) echo "${file}: source file" ;;
-*) echo "${file}: generic file" ;;
-esac
-done
-echo "there are ${DIRS} directories and ${FILES} files"
-ls | grep "ZxY--!!!WKW"
-if [[ $? != 0 ] ; then # exit code of last command
-echo "ZxY--!!!WKW not found"
-fi
-echo "enough... type 'man bash' if you want more info."
-
-----
-
-
-
-
-!! 5.4 C
-
-
-
-
-
-
-Linux is an excellent environment to program in C. Taken for granted that
-you know C, here are a couple of guidelines. To compile your standard
-hello.c you'll use the gcc compiler, which comes as part of Linux
-and has the same syntax as g77:
-
-
-
-
-
-$ gcc -O2 -o hello hello.c
-
-
-
-
-To link a library to a program, add the switch -l<libname>.
-For example, to link the math library and optimize do
-
-
-
-
-
-$ gcc -O2 -o mathprog mathprog.c -lm
-
-
-
-
-(The -l<libname> switch forces gcc to link the library
-/usr/lib/lib<libname>.a; so -lm links
-/usr/lib/libm.a).
-
-
-When your program is made of several source files, you'll need to use the
-utility make described above. Just use gcc and C source files in
-the makefile.
-
-
-You can invoke some help about the C functions, that are covered by man
-pages, section 3; for example,
-
-
-
-
-
-$ man 3 printf
-
-
-
-
-There are lots of libraries available out there; among the first you'll want
-to use are ncurses, to handle text mode effects, and svgalib, to
-do graphics.
-
-
-
-
-
-
-----
-
-!! 6. Graphics
-
-
-
-
-
-Among the scores of graphic packages available, gnuplot stands out
-for its power and ease of use. Go to X and type gnuplot, and have
-two sample data files ready: 2D-data.dat (two data per line), and
-3D-data.dat (three data per line).
-
-
-Examples of 2-D graphs:
-
-
-
-
-
-gnuplot> set title "my first graph"
-gnuplot> plot '2D-data.dat'
-gnuplot> plot '2D-data.dat' with linespoints
-gnuplot> plot '2D-data.dat', sin(x)
-gnuplot> plot [[-5:10] '2D-data.dat'
-
-
-
-
-Example of 3-D graphs (each `row' of X values is followed by a blank
-line):
-
-
-
-
-
-gnuplot> set parametric ; set hidden3d ; set contour
-gnuplot> splot '3D-data.dat' using 1:2:3 with linespoints
-
-
-
-
-A single-column datafile (e.g., a time series) can also be plotted as a 2-D
-graph:
-
-
-
-
-
-gnuplot> plot [[-5:15] '2D-data-1col.dat' with linespoints
-
-
-
-
-or as a 3-D graph (blank lines in the datafile, as above):
-
-
-
-
-
-gnuplot> set noparametric ; set hidden3d
-gnuplot> splot '3D-data-1col.dat' using 1 with linespoints
-
-
-
-
-To print a graph: if the command to print on your Postscript printer is
-lpr -Pps file.ps, issue:
-
-
-
-
-
-gnuplot> set term post
-gnuplot> set out '| lpr -Pps'
-gnuplot> replot
-
-
-
-
-then type set term x11 to restore. Don't get confused---the last print
-will come out only when you quit gnuplot.
-
-
-For more info, type help or see the examples in directory
-/usr/lib/gnuplot/demos/, if you have it.
-
-
-
-
-
-
-----
-
-!! 7. Mail and Internet Tools
-
-
-
-
-
-Since Internet was born on UNIX machines, you find plenty of nice and
-easy-to-use applications under Linux. Here are just some:
-
-
-
-
-
-**** __Mail__: use elm or pine to handle your email; both
-programs have on-line help. For short messages, you could use mail, as
-in mail -s "hello mate" user@somewhere < msg.txt. You may like programs
-like xmail or some such.
-
-****
-
-**** __Newsgroups__: use tin or slrn, both very intuitive and
-self-explanatory.
-
-****
-
-**** __ftp__: apart from the usual character-based ftp, ask your
-sysadm to install the full-screen ncftp or a graphical ftp client like
-xftp.
-
-****
-
-**** __WWW__: the ubiquitous netscape, or xmosaic,
-chimera, and arena are graphical web browsers; a character-based
-one is lynx, quick and effective.
-
-****
-
-
-
-
-----
-
-!! 8. Advanced Topics
-
-
-
-
-
-Here the game gets tough. Learn these features, then you'll be ready to say
-that you `know something about Linux' ;-)
-
-
-
-
-
-
-
-!! 8.1 Permissions and Ownership
-
-
-
-
-
-
-Files and directories have permissions (`protections') and ownership, just
-like under VMS. If you can't run a program, or can't modify a file, or can't
-access a directory, it's because you don't have the permission to do so,
-and/or because the file doesn't belong to you. Let's have a look at the
-following example:
-
-
-
-
-
-$ ls -l /bin/ls
--rwxr-xr-x 1 root bin 27281 Aug 15 1995 /bin/ls*
-
-
-
-
-The first field shows the permissions of the file ls (owner root,
-group bin). There are three types of ownership: owner, group, and others
-(similar to VMS owner, group, world), and three types of permissions:
-read, write (and delete), and execute.
-
-
-From left to right, - is the file type (- = ordinary file, d
-= directory, l = link, etc); rwx are the permissions for the file
-owner (read, write, execute); r-x are the permissions for the group of
-the file owner (read, execute); r-x are the permissions for all other
-users (read, execute).
-
-
-To change a file's permissions:
-
-
-
-
-
-$ chmod <whoXperm> <file>
-
-
-
-
-where who is u (user, that is owner), g (group), o (other),
-X is either + or -, perm is r (read), w (write), or
-x (execute). Examples:
-
-
-
-
-
-$ chmod u+x file
-
-
-
-
-this sets the execute permission for the file owner. Shortcut:
-chmod +x file.
-
-
-
-
-
-$ chmod go-wx file
-
-
-
-
-this removes write and execute permission for everyone except the owner.
-
-
-
-
-
-$ chmod ugo+rwx file
-
-
-
-
-this gives everyone read, write, and execute permission.
-
-
-A shorter way to refer to permissions is with numbers: rwxr-xr-x can be
-expressed as 755 (every letter corresponds to a bit: --- is ,
---x is 1, -w- is 2...).
-
-
-For a directory, rx means that you can cd to that directory, and
-w means that you can delete a file in the directory (according to the
-file's permissions, of course), or the directory itself. All this is only
-part of the matter---RMP.
-
-
-To change a file's owner:
-
-
-
-
-
-$ chown username file
-
-
-
-
-To sum up, a table:
-
-
-
-
-
-VMS Linux Notes
-------------------------------------------------------------------------------
-SET PROT=(O:RW) file.txt $ chmod u+rw file.txt
-$ chmod 600 file.txt
-SET PROT=(O:RWED,W) file $ chmod u+rwx file
-$ chmod 700 file
-SET PROT=(O:RWED,W:RE) file $ chmod 755 file
-SET PROT=(O:RW,G:RW,W) file $ chmod 660 file
-SET FILE/OWNER_UIC=JOE file $ chown joe file
-SET DIR/OWNER_UIC=JOE [[.dir] $ chown joe dir/
-
-
-
-
-
-
-
-
-
-!! 8.2 Multitasking: Processes and Jobs
-
-
-
-
-
-
-More about running programs. There are no `batch queues' under Linux as
-you're used to; multitasking is handled very differently. Again, this is
-what the typical command line looks like:
-
-
-
-
-
-$ command -s1 -s2 ... -sn par1 par2 ... parn < input > output &
-
-
-
-
-where -s1, ..., -sn are the program switches,
-par1, ..., parn are the program parameters.
-
-
-Now let's see how multitasking works. Programs, running in foreground or
-background, are called `processes'.
-
-
-
-
-
-**** To launch a process in background:
-
-
-$ progname [[-switches] [[parameters] [[< input] [[> output] &
-[[1] 234
-
-
-the shell tells you what the `job number' (the first digit; see below) and
-PID (Process IDentifier) of the process are. Each process is identified
-by its PID.
-
-****
-
-**** To see how many processes there are:
-
-
-$ ps -ax
-
-
-This will output a list of currently running processes.
-
-****
-
-**** To kill a process:
-
-
-$ kill <PID>
-
-
-You may need to kill a process when you don't know how to quit it
-the right way... ;-). Sometimes, a process will only be killed by
-one of the following:
-
-
-$ kill -15 <PID>
-$ kill -9 <PID>
-
-
-
-****
-
-
-
-In addition to this, the shell allows you to stop or temporarily suspend a
-process, send a process to background, and bring a process from background
-to foreground. In this context, processes are called `jobs'.
-
-
-
-
-
-**** To see how many jobs there are:
-
-
-$ jobs
-
-
-jobs are identified by the numbers the shell gives them, not by their PID.
-
-****
-
-**** To stop a process running in foreground:
-
-
-$ CTRL-C
-
-
-(it doesn't always work)
-
-****
-
-**** To suspend a process running in foreground:
-
-
-$ CTRL-Z
-
-
-(ditto)
-
-****
-
-**** To send a suspended process into background (it becomes a job):
-
-
-$ bg <job>
-
-
-
-****
-
-**** To bring a job to foreground:
-
-
-$ fg <job>
-
-
-
-****
-
-**** To kill a job:
-
-
-$ kill <%job>
-
-
-
-****
-
-
-
-
-
-!!8.3 Files, Revisited
-
-
-
-
-
-
-More information about files.
-
-
-
-
-
-**** __stdin, stdout, stderr__: under UNIX, every system component is
-treated as if it were a file. Commands and programs get their input from a
-`file' called stdin (standard input; usually, the keyboard), put their
-output on a `file' called stdout (usually, the screen), and error
-messages go to a `file' called stderr (usually, the screen).
-Using < and > you redirect input and output to a different
-file. Moreover, >> appends the output to a file instead of
-overwriting it; 2> redirects error messages (stderr); 2>&1
-redirects stderr to stdout, while 1>&2 redirects stdout to stderr.
-There's a `black hole' called /dev/null: everything redirected to
-it disappears;
-
-****
-
-**** __wildcards__: '*' is almost the same. Usage: * matches all
-files except the hidden ones; .* matches all hidden files; *.* matches
-only those that have a '.' in the middle, followed by other characters;
-p*r matches both `peter' and `piper'; *c* matches both `picked' and `peck'.
-'%' becomes '?'. There is another wildcard: the
-[[]. Usage: [[abc]* matches files starting with a, b, c;
-*[[I-N,1,2,3] matches files ending with I, J, K, L, M, N, 1, 2, 3;
-
-****
-
-**** mv (RENAME) doesn't work for multiple files; that is,
-mv *.xxx *.yyy won't work;
-
-****
-
-**** use cp -i and mv -i to be warned when a file is going to
-be overwritten.
-
-****
-
-
-
-
-
-
-
-
-!! 8.4 Print Queues
-
-
-
-
-
-
-Your prints are queued, like under VMS. When you issue a print command, you
-may specify a printer name. Example:
-
-
-
-
-
-$ lpr file.txt # this goes to the standard printer
-$ lpr -Plaser file.ps # this goes to the printer named 'laser'
-
-
-
-
-To handle the print queues, you use the following commands:
-
-
-
-
-
-VMS Linux
-------------------------------------------------------------------------------
-$ PRINT file.ps $ lpr file.ps
-$ PRINT/QUEUE=laser file.ps $ lpr -Plaser file.ps
-$ SHOW QUEUE $ lpq
-$ SHOW QUEUE/QUEUE=laser $ lpq -Plaser
-$ STOP/QUEUE $ lprm <item>
-
-
-
-
-
-
-
-
-----
-
-!! 9. Configuring
-
-
-
-
-
-Your sysadm has already provided you with a number of configuration files
-like .xinitrc, .bash_profile, .inputrc, and many others. The
-ones you may want to edit are:
-
-
-
-
-
-**** .bash_profile or .profile: read by the shell at login
-time. It's like LOGIN.COM;
-
-****
-
-**** .bash_logout: read by the shell at logout. It's like
-LOGOUT.COM;
-
-****
-
-**** .bashrc: read by non--login shells.
-
-****
-
-**** .inputrc: this file customises the key bindings and the
-behaviour of the shell.
-
-****
-
-
-
-To give you an example, I'll include my .bash_profile (abridged):
-
-
-
-----
-
-# $HOME/.bash_profile
-# don't redefine the path if not necessary
-echo $PATH | grep $LOGNAME > /dev/null
-if [[ $? != 0 ]
-then
-export PATH="$PATH:/home/$LOGNAME/bin" # add my dir to the PATH
-fi
-export PS1='LOGNAME:\w\$ '
-export PS2='Continued...>'
-# aliases
-alias bin="cd ~/bin" ; alias cp="cp -i" ; alias d="dir"
-alias del="delete" ; alias dir="/bin/ls $LS_OPTIONS --format=vertical"
-alias ed="jed" ; alias mv='mv -i'
-alias u="cd .." ; alias undel="undelete"
-# A few useful functions
-inst() # Install a .tar.gz archive in current directory.
-{
-gzip -dc $1 | tar xvf -
-}
-cz() # List the contents of a .zip archive.
-{
-unzip -l $*
-}
-ctgz() # List the contents of a .tar.gz archive.
-{
-for file in $* ; do
-gzip -dc ${file} | tar tf -
-done
-}
-tgz() # Create a .tgz archive a la zip.
-{
-name=$1 ; tar -cvf $1 ; shift
-tar -rf ${name} $* ; gzip -S .tgz ${name}
-}
-
-----
-
-
-And this is my .inputrc:
-
-
-
-----
-
-# $HOME/.inputrc
-# Last modified: 16 January 1997.
-#
-# This file is read by bash and defines key bindings to be used by the shell;
-# what follows fixes the keys END, HOME, and DELETE, plus accented letters.
-# For more information, man readline.
-"\e[[1~": beginning-of-line
-"\e[[3~": delete-char
-"\e[[4~": end-of-line
-set bell-style visible
-set meta-flag On
-set convert-meta Off
-set output-meta On
-set horizontal-scroll-mode On
-set show-all-if-ambiguous On
-# (F1 .. F5) are "\e[[[[A" ... "\e[[[[E"
-"\e[[[[A": "info "
-
-----
-
-
-
-
-
-
-----
-
-!! 10. Useful Programs
-
-
-
-
-
-
-
-!!10.1 Browsing Files: less
-
-
-
-
-
-
-You'll use this file browser every day, so I'll give you a couple of tips to
-use it at best. First of all, ask your sysadm to configure less so as
-it can display not only plain text files, but also compressed files,
-archives, and so on.
-
-
-Like recent versions of TYPE, less lets you browse files
-in both directions. It also accepts several commands that are issued
-pressing a key. The most useful are:
-
-
-
-
-
-**** first of all, press q to leave the browser;
-
-****
-
-**** h gives you extensive help;
-
-****
-
-**** g to go to beginning of file, G to the end, number+g
-to go to line `number' (e.g. 125g), number+% to move to that
-percentage of the file;
-
-****
-
-**** /pattern searches forwards for `pattern'; n searches
-forwards for the next match; ?pattern and N search backwards;
-
-****
-
-**** m+letter marks current position (e.g. ma); '+letter go
-to the marked position.
-
-****
-
-**** :e examines a new file;
-
-****
-
-**** !command executes the shell command.
-
-****
-
-
-
-
-
-
-
-
-!! 10.2 Numbered Backups Under Linux
-
-
-
-
-
-
-Alas, Linux doesn't still support file version numbers, but you overcome
-this limitation in two ways. The first is to use RCS, the Revision Control
-System, which allows you to keep previous versions of a file. RCS is
-covered in ``The RCS MINI-HOWTO'' (
-http://sunsite.unc.edu/mdw/HOWTO/mini/RCS.html).
-
-
-The second way is to use an editor that knows how to deal with numbered
-backups; emacs and jed are OK. In emacs, add
-these lines in your .emacs:
-
-
-
-
-
-(setq version-control t)
-(setq kept-new-versions 15) ;;; or any other value
-(setq kept-old-versions 15)
-(setq backup-by-copying-when-linked t)
-(setq backup-by-copying-when-mismatch t)
-
-
-
-
-In jed, make sure you have version .98.7 or newer; the patch for
-numbered backups is available on
-http://ibogeo.df.unibo.it/guido/slang/backups.sl .
-
-
-
-
-
-
-
-!!10.3 Archiving: tar & gzip
-
-
-
-
-
-
-Under UNIX there are some widely used applications to archive and
-compress files. tar is used to make archives, that is collections of
-files. To make a new archive:
-
-
-
-
-
-$ tar -cvf <archive_name.tar> <file> [[file...]
-
-
-
-
-To extract files from an archive:
-
-
-
-
-
-$ tar -xpvf <archive_name.tar> [[file...]
-
-
-
-
-To list the contents of an archive:
-
-
-
-
-
-$ tar -tf <archive_name.tar> | less
-
-
-
-
-Files can be compressed to save disk space using compress, which is
-obsolete and shouldn't be used any more, or gzip:
-
-
-
-
-
-$ compress <file>
-$ gzip <file>
-
-
-
-
-that creates a compressed file with extension .Z (compress) or .gz
-(gzip). These programs don't make archives, but compress files
-individually. To decompress, use:
-
-
-
-
-
-$ compress -d <file.Z>
-$ gzip -d <file.gz>
-
-
-
-
-RMP.
-
-
-The unarj, zip and unzip utilities are also available. Files
-with extension .tar.gz or .tgz (archived with tar, then
-compressed with gzip) are very common in the UNIX world. Here's how to
-list the contents of a .tar.gz archive:
-
-
-
-
-
-$ tar -ztf <file.tar.gz> | less
-
-
-
-
-To extract the files from a .tar.gz archive:
-
-
-
-
-
-$ tar -zxf <file.tar.gz>
-
-
-
-
-
-
-
-
-----
-
-!! 11. Real Life Examples
-
-
-
-
-
-UNIX' core idea is that there are many simple commands that can linked
-together via piping and redirection to accomplish even really complex tasks.
-Have a look at the following examples. I'll only explain the most complex
-ones; for the others, please study the above sections and the man pages.
-
-
-__Problem__: ls is too quick and the file names fly away.
-
-
-__Solution__:
-
-
-
-
-
-$ ls | less
-
-
-
-
-__Problem__: I have a file containing a list of words. I want to sort it
-in reverse order and print it.
-
-
-__Solution__:
-
-
-
-
-
-$ cat myfile.txt | sort -r | lpr
-
-
-
-
-__Problem__: my data file has some repeated lines! How do I get rid of them?
-
-
-__Solution__:
-
-
-
-
-
-$ sort datafile.dat | uniq > newfile.dat
-
-
-
-
-__Problem__: I have a file called 'mypaper.txt' or 'mypaper.tex' or some
-such somewhere, but I don't remember where I put it. How do I find it?
-
-
-__Solution__:
-
-
-
-
-
-$ find ~ -name "mypaper*"
-
-
-
-
-Explanation: find is a very useful command that lists all the files
-in a directory tree (starting from ~ in this case). Its output
-can be filtered to meet several criteria, such as -name.
-
-
-__Problem__: I have a text file containing the word 'entropy' in this
-directory, is there anything like SEARCH?
-
-
-__Solution__: yes, try
-
-
-
-
-
-$ grep -l 'entropy' *
-
-
-
-
-__Problem__: somewhere I have text files containing the word 'entropy', I'd
-like to know which and where they are. Under VMS I'd use search entropy
-[[...]*.*;*, but grep can't recurse subdirectories. Now what?
-
-
-__Solution__:
-
-
-
-
-
-$ find . -exec grep -l "entropy" {} \; 2> /dev/null
-
-
-
-
-Explanation: find . outputs all the file names starting from the
-current directory, -exec grep -l "entropy" is an action to be
-performed on each file (represented by {}), \
-terminates the command. If you think this syntax is awful, you're right.
-
-
-In alternative, write the following script:
-
-
-
-----
-
-#!/bin/sh
-# rgrep: recursive grep
-if [[ $# != 3 ]
-then
-echo "Usage: rgrep --switches 'pattern' 'directory'"
-exit 1
-fi
-find $3 -name "*" -exec grep $1 $2 {} \; 2> /dev/null
-
-----
-
-
-Explanation: grep works like search, and combining it with
-find we get the best of both worlds.
-
-
-__Problem__: I have a data file that has two header lines, then every
-line has 'n' data, not necessarily equally spaced. I want the 2nd and
-5th data value of each line. Shall I write a Fortran program...?
-
-
-__Solution__: nope. This is quicker:
-
-
-
-
-
-$ awk 'NL > 2 {print $2, "\t", $5}' datafile.dat > newfile.dat
-
-
-
-
-Explanation: the command awk is actually a programming language:
-for each line starting from the third in datafile.dat, print out
-the second and fifth field, separated by a tab. Learn some awk---it
-saves a lot of time.
-
-
-__Problem__: I've downloaded an FTP site's ls-lR.gz to check its
-contents. For each subdirectory, it contains a line that reads "total xxxx",
-where xxxx is size in kbytes of the dir contents. I'd like to get the grand
-total of all these xxxx values.
-
-
-__Solution__:
-
-
-
-
-
-$ zcat ls-lR.gz | awk ' $1 == "total" { i += $2 } END {print i}'
-
-
-
-
-Explanation: zcat outputs the contents of the .gz file and pipes
-to awk, whose man page you're kindly requested to read ;-)
-
-
-__Problem__: I've written a Fortran program, myprog, to calculate a
-parameter from a data file. I'd like to run it on hundreds of data files
-and have a list of the results, but it's a nuisance to ask each time for
-the file name. Under VMS I'd write a lengthy command file, and under Linux?
-
-
-__Solution__: a very short script. Make your program look for the data
-file 'mydata.dat' and print the result on the screen (stdout), then
-write the following script:
-
-
-
-----
-
-#!/bin/sh
-# myprog.sh: run the same command on many different files
-# usage: myprog.sh *.dat
-for file in $* # for all parameters (e.g. *.dat)
-do
-# append the file name to result.dat
-echo -n "${file}: " >> results.dat
-# copy current argument to mydata.dat, run myprog
-# and append the output to results.dat
-cp ${file} mydata.dat ; myprog >> results.dat
-done
-
-----
-
-
-__Problem__: I want to replace `geology' with `geophysics' in all my
-text files. Shall I edit them all manually?
-
-
-__Solution__: nope. Write this shell script:
-
-
-
-----
-
-#!/bin/sh
-# replace $1 with $2 in $*
-# usage: replace "old-pattern" "new-pattern" file [[file...]
-OLD=$1 # first parameter of the script
-NEW=$2 # second parameter
-shift ; shift # discard the first 2 parameters: the next are the file names
-for file in $* # for all files given as parameters
-do
-# replace every occurrence of OLD with NEW, save on a temporary file
-sed "s/$OLD/$NEW/g" ${file} > ${file}.new
-# rename the temporary file as the original file
-/bin/mv ${file}.new ${file}
-done
-
-----
-
-
-__Problem__: I have some data files, I don't know their length and have to
-remove their last but one and last but two lines. Er... manually?
-
-
-__Solution__: no, of course. Write this script:
-
-
-
-----
-
-#!/bin/sh
-# prune.sh: removes n-1th and n-2th lines from files
-# usage: prune.sh file [[file...]
-for file in $* # for every parameter
-do
-LINES=`wc -l $file | awk '{print $1}'` # number of lines in file
-LINES=`expr $LINES - 3` # LINES = LINES - 3
-head -n $LINES $file > $file.new # output first LINES lines
-tail -n 1 $file >> $file.new # append last line
-done
-
-----
-
-
-I hope these examples whetted your appetite...
-
-
-
-
-
-
-----
-
-!!12. Tips You Can't Do Without
-
-
-
-
-
-
-
-
-**** __Command completion__: pressing <TAB> when issuing a command
-will complete the command line for you. Example: you have to type
-less this_is_a_long_name; typing in less thi<TAB>
-will suffice. (If you have other files that start with the same
-characters, supply enough characters to resolve any ambiguity.)
-
-****
-
-**** __Back-scrolling__: pressing SHIFT--PAG UP (the grey key) allows
-you to backscroll a few pages, depending on your PC's video memory.
-
-****
-
-**** __Resetting the screen__: if you happen to more or cat
-a binary file, your screen may end up full of garbage. To fix things,
-blind type reset or this sequence of characters:
-echo CTRL-V ESC c RETURN.
-
-****
-
-**** __Pasting text__: in console, see below; in X, click and drag to
-select the text in an xterm window, then click the middle button
-(or the two buttons together if you have a two-button mouse) to paste.
-
-****
-
-**** __Using the mouse__: ask your sysadm to install gpm, a mouse
-driver for the console. Click and drag to select text, then right click
-to paste the selected text. It works across different VCs.
-
-****
-
-
-
-
-
-
-
-----
-
-!!13. Reading VMS tapes from Linux
-
-
-
-
-
-(This section was written by Mike Miller)
-
-
-
-
-!!13.1 Introduction
-
-
-
-
-
-
-From time to time you may want to read tapes made on a VMS machine (or tapes
-that are made to be readable by VMS and *nix systems). In general, this is
-quite easy for DECFILES11A tapes.
-
-
-Although you may be reading this as part of a Linux mini-HOWTO, I believe
-that the information here is applicable to any *nix system - I've done this
-on Linux, HP, Sun and DEC *nix systems. The main platform dependences that I
-know are device names, which can differ on different systems, and the
-options to mt for specifying the device name (for example, mt -f on Linux
-and mt -t on HPUX 9).
-
-
-Caveat - I've only tried this with Exabyte 8mm SCSI tape drives. If you've
-read other formats (still got those 9-tracks lying around?) let me know and
-I'll add a note here.
-
-
-
-
-
-
-
-!!13.2 The Basics
-
-
-
-
-
-
-When reading a tape that has been made with the VMS ``copy'' command (or has
-at least been made to look like it was made with copy) all you need to know
-is there will be three files on the tape for each actual data file - a
-header, the data, and a trailer. The header and trailer are interesting in
-that they contain info on the file as it existed under VMS. The data is,
-well, the data. Each of these files can be extracted from the tape with the
-dd command. The tape can be positioned by skipping around with the mt
-command.
-
-
-Example: I've got VMS tape with a series of files on it. The first two were
-originally named ce66-2.evt and ce66-3.evt on a VMS system. The tape label
-is c66a2.
-
-
-If I execute these commands:
-
-
-
-
-
-> dd if=$TAPE bs=16k of=header1
-> dd if=$TAPE bs=16k of=data1
-> dd if=$TAPE bs=16k of=trailer1
-> dd if=$TAPE bs=16k of=header2
-> dd if=$TAPE bs=16k of=data2
-> dd if=$TAPE bs=16k of=trailer2
-
-
-
-
-I'm left with six files: header1, data1, trailer1, header2, data2 and
-trailer2. The syntax here is if="input file", bs="block size" and
-of="output file". TAPE is expected to be a variable containing the device
-name of your tape drive - for example, /dev/nts0 if you are using the first
-SCSI tape on Linux.
-
-
-If you wanted to read the second file, but not the first, you didn't care
-about the header, and you wanted to use the original file name, do this:
-
-
-
-
-
-> mt -f $TAPE fsf 4
-> dd if=$TAPE bs=16k of=ce66-2.evt
-> mt -f $TAPE fsf 1
-
-
-
-
-Note the 4 - skip three files for the first file on the tape and one for the
-next header. The second mt skips the second file's trailer and positions
-the tape at the beginning of the next file - the third VMS header. You can
-also use mt to skip backwards (bsf), rewind (rewind) and rewind and unload
-the tape (offline, rewoffl).
-
-
-
-
-
-
-
-!!13.3 Some details
-
-
-
-
-
-
-
-
-
-The header and trailer files contain uppercase ASCII data used by VMS to
-store file information such as block size. They also contain the file name,
-which can be handy if you want to build scripts that automate read files or
-search for a particular file. The first header on a tape volume is slightly
-different than subsequent headers.
-
-
-For a file that is the first file on the tape, as in header1 of the above
-example, the first four characters will be "VOL1" followed by the volume
-name. In the example, header1 starts with "VOL1C66A2". This is followed by
-a series of spaces terminated with a numeral. After that is the string
-"HDR1" which indicates that this is a file header. The characters
-immediately following the HDR1 string are the VMS file name. In in the
-example, this is "HDR1CE66-2.EVT". The next field is the volume name again.
-
-
-For files that are not the first file on the tape, the initial VOL1 field is
-not present. Other than that the header has the same structure as for the
-initial file. Another useful field is the 7th field, which will end with
-"DECFILES11A". This must be present on tapes that conform to the DEC
-Files11A standard.
-
-
-
-
-
-field initial header subsequent headers
-===== ============= ==================
-1 VOL1 + volume name HDR1 + file name
-2 3HDR1 + file name volume name
-3 volume name
-6 ...DECFILES11A
-7 ...DECFILES11A
-
-
-
-
-For full details on the header and trailer format, see the DEC FILES11A
-documentation (on the orange/grey wall - ask your local VMS folks :-).
-
-
-
-
-
-
-
-!!13.4 Comment on Block Size
-
-
-
-
-
-
-In the example, I used a block size of 16k. On a *nix system, there is no
-block size associated with a file on disk while, under VMS, each file has a
-specific block size. That means that block size doesn't matter too much on
-the Linux end... unless it makes it hard to read the tape. If you have
-difficulty figuring out the block size and reading a tape, you can try
-setting the hardware block size on your tape drive using `mt -f $TAPE setblk
-'. The exact form of the setblk option (and its availability) may depend
-on the version of mt, the tape drive hardware interface and on your
-particular flavor of *nix.
-
-
-(Thanks to Wojtek Skulski (
-skulski@nsrlc6.nsrl.rochester.edu)
-for pointing out setblk.)
-
-
-
-
-
-
-----
-
-!!14. The End
-
-
-
-
-
-
-
-!!14.1 Copyright
-
-
-
-
-
-
-Unless otherwise stated, Linux HOWTO documents are copyrighted by their
-respective authors. Linux HOWTO documents may be reproduced and distributed
-in whole or in part, in any medium physical or electronic, as long as this
-copyright notice is retained on all copies. Commercial redistribution is
-allowed and encouraged; however, the author would like to be notified of any
-such distributions.
-
-
-All translations, derivative works, or aggregate works incorporating any
-Linux HOWTO documents must be covered under this copyright notice. That is,
-you may not produce a derivative work from a HOWTO and impose additional
-restrictions on its distribution. Exceptions to these rules may be granted
-under certain conditions; please contact the Linux HOWTO coordinator at the
-address given below.
-
-
-In short, we wish to promote dissemination of this information through as
-many channels as possible. However, we do wish to retain copyright on the
-HOWTO documents, and would like to be notified of any plans to redistribute
-the HOWTOs.
-
-
-If you have questions, please contact Tim Bynum, the Linux HOWTO
-coordinator, at
-linux-howto@sunsite.unc.edu via email.
-
-
-
-
-
-
-
-!!14.2 Disclaimer
-
-
-
-
-
-
-This work was written following the experience we had at the Settore di
-Geofisica of the Universita' di Bologna (Italy), where a VAX 4000 has been
-superseded and replaced by Linux-based Pentium PCs. Most of my colleagues
-are VMS users, and some of them have switched to Linux.
-
-
-``From VMS to Linux HOWTO'' was written by Guido Gonzato,
-guido ``at'' ibogeo.df.unibo.it, and Mike Miller,
-miller5@uiuc.edu who contributed the section on reading VMS tapes.
-Many thanks to my colleagues and friends who helped me define the needs and
-habits of the average VMS user, especially to Dr. Warner Marzocchi.
-
-
-Please help me improve this HOWTO. I'm not a VMS expert and never will be,
-so your suggestions and bug reports are more than welcome
.
-
-
-Enjoy,
-
-
-Guido =8-)
-
-
-
-----
+Describe
[HowToVMStoLinuxHOWTO
] here.
