ZWcarp has asked for the wisdom of the Perl Monks concerning the following question:

Say I have a file with 30 columns and I want to add 1 to the number in column 15, but otherwise print the line as is. Is there a better way to do this then something like

perl -lane' print "$F[0]\t$F[2]\t$F[3]....\t" .$F[15]+1 . "\t$F[16] .....\t$F[30]"' file.txt

The dots representing $Fx\t ( or everything in-between) Any ideas? the shorter the better. Also i was thinking maybe a tricky substation might work but this could get difficult with more complex operations. Still.... open to any suggestions Thanks for your time.

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Re: Editing just one column in a file
by BrowserUk (Patriarch) on Nov 28, 2011 at 21:54 UTC 

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

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    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".
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      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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      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

        [download]
        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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