You almost never want .* A negated character class is generally better. For example m!/[(^/)]+$! will grab the last bit of the filepath reliably but the regex posted above in the map should DWIM

You could certainly code the example above as a one liner but it seems a waste of time to me. You can make a reusable 4 line script in less time than it will take fiddling. You can put options like -p -F -n on the shebang. As a one liner it would be like:

perl -F -ane 'print map{"$_\n"} map{ } grep { } @F' <file>
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where the map and grep blocks are as above.

Picking up with the theme you were following, I got this to work. I haven't thought alot about corner cases, performance or reusability, so Grandfather's and tachyon-II's solutions are probably better.

update: apparently I'm just confused on this matter && added comment on second s/// with no effect: I didn't like doing the substitution twice just to get the end-of-line anchor to work. Perhaps some wiser monks can explain that to me. update: That was before I added chomp, so never mind . . .

#/usr/bin/perl -W

$\="\n";

use strict;
use warnings;

while (<DATA>) {
    chomp;
    print $_;
    s/\/(?:[^\@:,\s+]*\/)(.*?)[\@:,\s+]*/\/new\/path\/$1/g;
    #s/\/(?:[^\@:,\s+]*\/)(.*?)[\@:,\s+]*$/\/new\/path\/$1/g;
    print $_;
    print '';
}


# produces:
# C:\chas_sandbox>
# 683879resp.pl
# file /user/name/some/path/to/filename@@ dumped: replaced /user/name/
+blah/blah/filename
# file /new/path/filename@@ dumped: replaced /new/path/filename
#
# @@@@user/some/file/filename.sdc: dumped
# @@@@user/new/path/filename.sdc: dumped

__DATA__
file /user/name/some/path/to/filename@@ dumped: replaced /user/name/bl
+ah/blah/filename
@@@@user/some/file/filename.sdc: dumped
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