Gopher

What is Gopher?

From: http://en.wikipedia.org/wiki/Gopher_(protocol)

The Gopher protocol is a TCP/IP Application layer protocol designed for distributing, searching, and retrieving documents over the Internet […]. The protocol offers some features not natively supported by the Web and imposes a much stronger hierarchy on information stored on it.

You can find more info here:

• FAQ for GOPHER
• http://www.scn.org/~bkarger/gopher-manifesto
• http://gopher.floodgap.com/overbite/relevance.html

There are many ways to view gopherspace. Here are the easiest ways you can view gopher pages from the SDF shell

Additionally, you can issue the gopher command, either from the SDF shell or from within the mkgopher command prompt. This command can be also used to create your gopherspace as described below, and also includes a very basic browser to explore gopherspace.

The command mkgopher can be used to create, manage and view your gopherspace.

When you run mkgopher, you will be given a command prompt. You can issue the HELP command here to get a list of the available commands:

    HOWTO                 - Tips on managing your GOPHERSPACE
    setup                 - First step, create your GOPHERSPACE
    chmod                 - Set/Restore file permissions
    title                 - Title your site
    describe              - Create a site description
    mkdir     {directory} - Create a directory
    rmdir     {directory} - Delete a directory
    edit       {filename} - Publish a document
    upload     {filename} - Transfer a file via ZMODEM to SDF
    ls                    - List the current directory
    cd        {directory} - Change directory
    pwd                   - Present working directory
    gopher                - Browse your site
    quit

The setup command will create a directory in your $HOME called gopher (This directory is a link to /ftp/pub/users/$USER/ ). On it, you can put all the files you want to be available in your Gopherspace.

Once you create your Gopherspace, the files you publish will be available at gopher://sdf.org:70/1/users/$USER/
( currently, the directory listing at gopher://sdf.org:70/1/users/ doesn't appear to list all user directories. You may have to directly navigate to gopher://sdf.org:70/1/users/$USER/ in order to view your files.)

You can issue the gopher command, either from the SDF shell or from within the mkgopher command prompt. This gives a very basic browser to browse your site and also explore gopherspace.

You can use mkgopher to publish documents, create directories, etc. You can also manage your Gopherspace manually. If you decide to do so, remember that the server will not display your content if it is not already visible to everyone. That is, files need to world-readable (chmod o+r $HOME/gopher/yourfile), directories need also to be world executable (chmod o+rx $HOME/gopher/yourdir), etc. The gopher server (Gophernicus) will serve executable files under /cgi-bin and also gophermaps which have executable permission as gopher CGIs or “moles” (see below). In the case of gophermaps, this is likely to result in errors, so make sure your gophermaps do not have execute permission (chmod -x $HOME/gopher/yourdir/gophermap).

The usual ‘mkgopher -p’ command has not yet been updated to reflect Gophernicus' permissions requirements. So you may need to reset your permissions for all files and directories in your gopher directory as noted above. The following two commands will revert all files to world-readable but non-executable, and all directories to world-readable but executable.

$ find ~/gopher/ -type f -print0 | xargs -0 chmod 644
$ find ~/gopher/ -type d -print0 | xargs -0 chmod 755

You may need to manually add execute permissions to any dynamic gophermaps or files under /cgi-bin after runnig these two commands.

Note: You can view the sample gophermap that comes with Gophernicus here: README.Gophermap

Say that you have file1.txt, file2.pdf, file3.rtf and dir in your Gopherspace (dir is a directory). That is,

$ ls -lF
drwxr-x---  2 $USER  nobody  512 Dec  2 10:15 dir/
-rw-r-----  1 $USER  nobody    6 Dec  2 10:14 file1.txt
-rw-r-----  1 $USER  nobody    6 Dec  2 10:14 file2.pdf
-rw-r-----  1 $USER  nobody    6 Dec  2 10:14 file3.rtf

When you visit it, if there is no file named gophermap (yes, this file has no extension) you'll see a list of the files and the directory, like this:

,,,                                                                 Gopher Menu
                                  Gopher Menu

 (DIR) dir
(FILE) file1.txt
(FILE) file2.pdf
(FILE) file3.rtf

If there is a gophermap file, the server will parse it and will present the content as you specified in gophermap.

The gophermap syntax is:

  XSome text here<TAB>/path/to/content<TAB>example.org<TAB>N

where the first character (X in the example) is an itemtype (more below), Some text here is the text that you want to be displayed, <TAB> is a tab character, /path/to/content is the location of the content, example.org is the server where the content is located and the last character (N in the example) is the server port (usually it's 70). Content after the second <TAB> is optional if you are linking to content in your Gopherspace.

The itemtype is one of these characters:

OK, let's say that you want to display a welcome message, a description for file1.txt, file2.pdfand dir, a link to an external server, a link to an http URL. Your gophermap should be like this:

Welcome to my Gopherspace!

0My text file	file1.txt
9My pdf file	file2.pdf
1My dir	dir

0Why is Gopher Still Relevant?	/gopher/relevance.txt	gopher.floodgap.com	70
hAn http link	URL:http://sdf.org/

Remember the gophermap syntax? Then be careful about tab characters. In the example above, there are some<TAB>s. For instance, the third line is

0My text file<TAB>file1.txt

while the seventh is

0Why is Gopher Still Relevant?<TAB>/gopher/relevance.txt<TAB>gopher.floodgap.com<TAB>70

How come the pdf file has an itemtype 9? Well, not every kind of file has its own itemtype, so you can use one that makes more sense.

Even if you don't need a blank line as the second line of your document, you can find this useful as there is a known Lynx bug that makes it display the second line together with the first (you can find a patch for this here: gopher://sdf.org/0/users/bulibuta/openbsd/patches/lynx-gopher-newline.patch).

This is (more or less) the output you'll see if you use a gophermap like the one in the example above:

,,,                                                                 Gopher Menu
                                  Gopher Menu

       Welcome to my Gopherspace!

(FILE) My text file
 (BIN) My pdf file
 (DIR) My dir

(FILE) Why is Gopher Still Relevant?
(HTML) An http link

A gopher log (glog or phlog) is similar to a blog, but on gopherspace. You can create your phlog and add it to the phlogosphere.

Maintaining a glog consists basically (but not necessarily) in creating an entry (in your log directory) and modifying your phlog gophermap so that the new entry is displayed with its creation date. There's a script that you can run on SDF called mkgopherentry (located in /sys/sdf/bin/mkgopherentry) that will allow you to do exactly that. It will also extract the first paragraph from the entry and will add it on the gophermap with a Continued… link that will point to the full post. Creating an entry is as simple as:

mkgopherentry title textfile

where the 2 arguments are self-explaining.

Say that you have two entries in your diary. If you use mkgopherentry, they will appear like:

entries

 --This is my second post!--
       Tuesday, December 01th, 2009
   Lorem ipsum dolor sit amet, consectetur adipiscing elit.
   Cras eros turpis, tristique semper aliquet sit amet,
   hendrerit vel enim. Integer pulvinar leo in dolor posuere
   blandit.
   Continued...
 
   --First post--
       Monday, November 30th, 2009
   First entry in my gopher log at SDF.
   Continued...

NOTE: You can use the ‘phlog’ command to add your phlog/glog to the gopher.club phlog listing, and you can then update the listing after you create a post by running the following command: “touch ~ftp/pub/users/$LOGNAME”

There are some software authored by SDF members that you could find useful if you want to maintain a gopher log.

• germ
  • gopher://sdf.org/1/users/wt/soft/my/germ/
• slerm
  • gopher://sdf.org/0/users/slugmax/about-slerm.txt
  • gopher://sdf.org/9/users/slugmax/code/slerm-1.8.tgz
  • http://slugmax.tx0.org/slerm-1.8.tgz
• glog
  • gopher://sdf.org/0/users/yargo/scripts/glog.sh
• mkphlog
  • gopher://sdf.org/1/users/octotep/scripts/mkphlog/phlogit
  • gopher://sdf.org/0/users/slugmax/code/phlogit.txt
• tirph
  • gopher://sdf.org/1/users/papa/tirph
• ugo
  • gopher://sdf.org/1/users/chr/scripts/ugo/

You can find more resources in the Glogging/Phlogging section at gopher://sdf.org/1/users/wt/soft/gopher.

The server used by SDF (Gophernicus) is able to serve moles. Moles are executable files under /cgi-bin that are processed by the server as CGIs. This means that you can write a script, that the server will execute and it will present the data that your mole dumps to standard output. With moles you don't have to declare a content type header. Moles get arguments from the address used to access the document and can be accessed with whatever itemtype makes sense for the kind of output the mole generates.

You can code moles with the language(s) you are comfortable and can use on SDF. Below we will see some examples using shell scripts.

Remember that your moles need to be executable (and readable) by everyone, and under /cgi-bin. So you will have to do: “chmod 755 YOURSCRIPT.cgi”

The following example will generate a random fortune:

#!/bin/sh
/usr/pkg/games/fortune

Easy enough, isn't it? As it is raw text, you can access it using am itemtype = 0, that is: gopher://sdf.org/0/users/YOUR-USERNAME/cgi-bin/fortune.cgi

Did you notice that fortune was called with a full path? OK, that's because the server's path is PATH=/sbin:/bin:/usr/sbin:/usr/bin. That means that if you call a program without a path, the server will search in /sbin, /bin, /usr/sbin and /usr/bin. There's no /usr/pkg/games, or other path in the server's $PATH (eventually, you can add a path of your choice with, e.g., “PATH=$PATH:/usr/pkg/games”).

The following example will generate a list of files on a specified directory. It will be possible to sort the content alphabetically or by modification time, based on how you access the script.

  #!/bin/sh
  
  directory=/ftp/pub/users/YOUR-USERNAME
  rel_dir=/users/YOUR-USERNAME
  server=sdf.org
  port=70
  
  # The internal field separator is set to be a newline
  IFS='
  '
  
  if [ -n "$1" -a "$1" = 'date' ] ; then
      ls_arg=t
  fi
  
  for i in $(ls -l${ls_arg} $directory) ; do

      content=$(echo "$i" | awk '{ print $9}')
      date=$(echo "$i" | awk '{ print $6,$7,$8}')
  
      if [ -z "$content" ] ; then
          continue
      fi
  
      if [ -d $directory/$i ] ; then
          itemtype=1
      else
          itemtype=0
      fi
  
      echo "$itemtype$content ($date) $rel_dir    $server $port"
  done

Note that the echo… line is
“ echo “$itemtype$content ($date)<TAB>$rel_dir<TAB>$server<TAB>$port” ”

If you go to gopher://sdf.org/1/users/YOUR-USERNAME/cgi-bin/ls.cgi , you will see a list of your files sorted alphabetically. If you access your mole as gopher://sdf.org/1/users/YOUR-USERNAME/cgi-bin/ls.cgi?date , then you'll see your files/directories sorted by modification time.

You can add some interactivity by using the itemtype 7. This itemtype is intended to make it possible to type some characters in a search field in your browser. However, you can use it to make it possible to pass arguments to your scripts. The following example will use some text you digit in the search field and will pass it through the program figlet.

#!/bin/sh

IFS='
'
  
for line in $(/usr/pkg/bin/figlet "$@") ; do
    echo "i$line"  # This is itemtype=i + text
done

When you access the script via gopher://sdf.org/7/users/YOUR-USERNAME/cgi-bin/figlet.cgi , your browser will ask you to input some text (the way it ask depends on the browser), then it will show your text as figlet transforms it.

The i in the echo… line is important here. Indeed, the document is been accessed with an itemtype 7 (but the same applies for itemtype 1), so the document should be structured similarly to gophermaps. It's not a gophermap, though. That's why you need to explicitily state the line should be displayed as simple (or inline) text.

Besides what was said in the last paragraph of the figlet.cgi example, there's also another thing to stress. In that example (as with anything that will be served as a virtual directory or with an itemtype 1 or 7), content won't be displayed if you access your script via floodgap proxy (and maybe others). In this case you will need to format the output of your script. Luckily this is very easy. For instance, in the figlet.cgi example you will need to modify the echo … line this way:

echo “i$i<TAB><TAB>error.host<TAB>1”

where <TAB> is a tab character (you should already know this!)C and error.host and 1 are, respectively, a fake server and port number (you could also have written fake instead of error.host and 300 instead of 1).

Traditional link (using RCS): http://sdf.org/?tutorials/gopher ,v 1.24 2020/01/01 22:37:47 niro Exp $