CODEWITHSUNDEEP
perl
Prabhakaran M
Prabhakaran M

Reputation: 15

tr command in perl to change the column values

My .txt file looks like as below (please consider it is 1GB file):

hello,12,abcd,xyz
welcome,13,abcd,yul
hai,14,abcd,ghk

Now, I want encrypt 1st and 3rd column as like below

zzyyy,12,zzzz,xyz
asdsddd,13,zzzz,yul
asd,14,zzzz,ghk

I have encrypt key like below

export key=ETAOINSHRDLUBCFGJMQPVWZYXK

Now, I need to apply this key in perl script to encrypt 1st and 3rd column in my file:

export key=ETAOINSHRDLUBCFGJMQPVWZYXK

perl -F, -lane '$F[$_] =~ tr/a-z/A-Z/ =~ tr/A-Z/"$key"/ for (0, 2); print join(",", @F)' file.txt

So, when run above script, the key not applied and second tr command not working. So, could you please kindly help to what is wrong in the script.

I simply need apply like below in above Perl script

tr "a-z" "A-Z" | tr "A-Z" "$key"

Upvotes: 1

Views: 152

Answers (1)

glenn jackman
glenn jackman

Reputation: 247042

I see this in the documentation for tr///:

there is never any variable interpolation, so "$" and "@" are always treated as literals.

So attempting to pass the key through the environment won't work. But you can do this to insert the shell variable into the perl code:

perl -F, -lane '
    sub encode { my $str = uc shift; $str =~ tr/A-Z/'"$key"'/r; }
    # ..............................................^^....^^
    $F[$_] = encode($F[$_]) for (0, 2);
    print join(",", @F)
' file.txt

output:

HIUUF,12,ETAO,xyz
ZIUAFBI,13,ETAO,yul
HER,14,ETAO,ghk

Or, use eval

perl -F, -lane '
    sub encode { my $str = uc shift; eval "\$str =~ tr/A-Z/$ENV{key}/r" }
    $F[$_] = encode($F[$_]) for (0, 2);
    print join(",", @F)
' file.txt

Upvotes: 3

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