"(a,b,c,d,e,f) = [line.split()[i] for i in (0,1,3,5,7,9)]" 
$ perl -Mstrict -Mwarnings -e '(a,b,c,d,e,f) = [line.split()[i] for i 
+in (0,1,3,5,7,9)]'
Bareword "line" not allowed while "strict subs" in use at -e line 1.
syntax error at -e line 1, near ")["
Execution of -e aborted due to compilation errors.

[download]

So, step one would be to learn Perl. See "Perl introduction for beginners".

"... extract with a one-line instruction ..."

Ask yourself why you think this requirement is necessary. It rarely has any benefits. It will often reduce readability and, as such, make your code more error-prone.

"... extract ... from a file record ..."

For records with fixed-width records, use unpack". See the perlpacktut tutorial; the "Packing Text" section has an example showing exactly how to do this.

For records with variable-width records, use split. Do be aware of these differences (the linked documentation has details): 

$ perl -E '$_ = " a0 a1 a2 \n"; my ($x, @y) = split; say "|$x|@y|";'
|a0|a1 a2|

$ perl -E '$_ = " a0 a1 a2 \n"; my ($x, @y) = split " "; say "|$x|@y|"
+;'
|a0|a1 a2|

$ perl -E '$_ = " a0 a1 a2 \n"; my ($x, @y) = split / /; say "|$x|@y|"
+;'
||a0 a1 a2
|

$ perl -E '$_ = " a0 a1 a2 \n"; my ($x, @y) = split /\s+/; say "|$x|@y
+|";'
||a0 a1 a2|

[download]
"... extract ... some selected fields ..."

There are a variety of ways to achieve this. The best one to choose will probably depend on how you want to subsequently process the selected fields. Here are a couple of examples: 

my @wanted = (extraction_function($string))[0, 1, 3];
my ($f1, $f2, undef, $f3) = extraction_function($string);

[download]

— Ken

In reply to Re: Extracting selected fields form file record by kcott
in thread Extracting selected fields form file record by Anonymous Monk

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