Purpose: demonstrate use of [uri] and [ftp] in a tcl script.

Goal:  when provided a series of ftp based URLs on the command line,
return info to the user as to whether the URLs exist or not.

This might be useful for someone maintaining a database of web
resources for instance!

----

One problem was in the default definition of ''DisplayMsg''. It is used to display state information (if ftp::VERBOSE is set). It also causes the system to ''throw'' errors if there are connection errors, instead of reporting them back as defined.

use 

 set ftp::VERBOSE

after the ''package require ftp'' to get a tracing of what the internal engine does. To disable the handling of errors redefine ''ftp::DisplayMsg''' with your own code.

----

New Problem: the following code generates this output:

 $ tclsh ~/xyz/tstftp.tcl  ftp://ftp.neosoft.com/languages/tcl/alcatel/code/calc.tk.gz
 C: Connection from 206.138.231.4:21
 C: 220 shockwave2.neosoft.com FTP server (Version wu-2.6.1(1) Mon Jul  31 10:44:05 CDT 2000) ready.
 C: 331 Guest login ok, send your complete e-mail address as password.
 C: 230 User ftp logged in.  Access restrictions apply.
 C: 200 Type set to I.
 C: 550 languages/tcl/alcatel/code: No such file or directory.
 Error changing directory to " languages/tcl/alcatel/code"
 unable to enter languages/tcl/alcatel/code

What I was expecting was the very last line - the previous output from the ftp server I was not expecting.  

[AK]: Change the DisplayMsg to supress the output of error messages (error branch in the switch), or set VERBOSE to 0 to supress all the output. Or prepend error messages with ''E: '' to let them like al the other tracing output.

----

Here is the code I now have

 #!/bin/sh
 # \
 exec tclsh "$0" ${1+"$@"}
 # Author: [Larry W. Virden] [LV], modified Andreas Kupries [AK]
 # Modified again by [LV]

 package require uri
 package require ftp

 set ftp::VERBOSE 1

 proc ftp::DisplayMsg {s msg {state ""}} {
    upvar ::ftp::ftp$s ftp
    variable VERBOSE 
        
    switch -exact -- $state {
        data {
            if { $VERBOSE } { puts $msg }
        }
        control {
            if { $VERBOSE } { puts $msg }
        }
        error {
            if { $VERBOSE } { puts $msg }
            #error "ERROR: $msg"
        }
        default {
            if { $VERBOSE } { puts $msg }
        }
    }
    return
 }

 foreach arg $argv {
    array set current [uri::split $arg]

    # parray current

    if { [ catch { set fdc [ftp::Open $current(host) anonymous enteryourname@here.com] } returncode ] } {
        puts stderr [format "unable to open %s\n" $$current(host)]
        continue
    }

    set ftp_dir [file dirname $current(path)]
    set ftp_file [file tail $current(path)]

    if { [ catch { set result [ftp::Cd $fdc $ftp_dir] } return ] } {
        puts stderr [format "unable to enter %s\n" $ftp_dir]
        continue
    }

    if { $result == 0 } {
        puts stderr [format "unable to enter %s\n" $ftp_dir]
        continue
    }
    ftp::NList $fdc "${ftp_file}*"
    ftp::Close $fdc
 }

 exit