in reply to Editing just one column in a file

perl -lane '++$F[15]; print join "\t", @F' file

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Re^2: Editing just one column in a file
by ZWcarp (Beadle) on Nov 28, 2011 at 22:14 UTC

    Ahhh ok brilliant. One more question.. why does this only print one column instead of the specified array range?I'm sure I'm doing something stupid but I can't find a good website or text with detailed stuff on specific command line perl

    perl -lane '$,="\t";print $F[0..6]'  file.txt Thanks so much!

    UPDATE Sorry, I got it, you just need to change the $ to a @ in front of F. Apologies

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Re^2: Editing just one column in a file
by vinian (Beadle) on Nov 29, 2011 at 02:04 UTC
    hi, i am confused about this, need your help. 
    echo "Just another perl monkers " | perl -lane 'print $F[0..3]'

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    Output: 
    Just

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    why it treat $F[0..3] as $F[0] but not $F[1]or $F[2]or $F[3].
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      Because the Perl syntax for an array slice is @a[ ... ].

      If you enable warnings, you'll see that by using $a[1..3], the 1..3 is treated as a flip-flop operator comparing against $., and under most circumstances will produce false, which in the numeric context gets taken as 0:

      c:\test>perl -wE"@a = 0..10; say $a[1..3]; say @a[1..3]"
Use of uninitialized value in range (or flip) at -e line 1.
Argument "" isn't numeric in array element at -e line 1.
0
123

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      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
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        Why is it that this

         perl -lane '$,="\t"; print @F[0..4] ."\t\t\t" . @F[25..30]' file.txt

        Does not do what I intended ( for the ranges to be printed by tabs, followed by three blank columns followed by another range). Thankyou for your help!

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        thanks, but i got something more strange 
        vinian@cc:~$ echo "Just another perl monker" | perl -w -lane 'print $F
+[0..3]'
Argument "" isn't numeric in array element at -e line 1, <> line 1.
Just
vinian@cc:~$ echo "Just another perl monker" | perl -w -lane 'print $F
+[1..3]'
another
vinian@cc:~$ echo "Just another perl monker" | perl -w -lane 'print $F
+[2..3]'
Argument "" isn't numeric in array element at -e line 1, <> line 1.
Just
vinian@cc:~$ echo "Just another perl monker" | perl -w -lane 'print $F
+[3..3]'
Argument "" isn't numeric in array element at -e line 1, <> line 1.
Just

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        when $F[1..3] there is no warnings and the output is $F[1]

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